Programming In C++ - 195.01.03
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C++ Programming Pragati Software Pvt. Ltd. www.pragatisoftware.com
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1 195.01.03
Table of Contents Module 1: Getting Started Module 2: Arrays Module 3: Functions Module 4: Pointers and References Module 5: Classes and Objects Module 6: Friend Keyword Module 7: Operator Overloading Module 8: Inheritance Module 9: Polymorphism and Abstract classes Module 10: Streams Module 11: File I/O Module 12: Exception Handling Module 13: RTTI and Casting Operators Module 14: Templates
5 63 77 104 132 168 173 184 199 208 218 224 236 247
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C++ Programming Developed by : Bjarne Stroustrup Where : Bell Telephone Laboratories When : 1979 Influenced by: C Influenced : C#, Java
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Features of C++ • • • • •
Object-oriented programming Portability Modular programming C Compatibility Speed
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Module 1: Getting Started • Overview
First C++ program Standard O/P and I/P in C++ Data types and Modifiers Variables and Constants Operators Loops and Conditions Type Conversions
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The first C++ program • • •
/* First.cpp */ #include using namespace std;
• • • • •
int main( ) { cout<<"Hello! This is my first C++ program\n"; return 0; }
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The first C++ program
contd…
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Standard Output Consider the statements cout<<“value of var1is :”; int var1=14; cout<< var1; cout<<“The addition of ”<
Syntax: cout<<“string”; cout<
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Standard Input Consider the statements cin rel="nofollow">> var1; cin>>x>>y;
Syntax:
cin>>variable1; cin>>cascade1>>cascade2;
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Data types • Fundamental data types in C++ Type Integer Character Floating Point Double precision floating point Boolean
Keyword int char float double bool
• Modifiers signed , unsigned short, long void Pragati Software Pvt. Ltd., 312, Lok Center, Marol-Maroshi Road, Marol, Andheri (East), Mumbai 400 059. www.pragatisoftware.com
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Data Type Modifiers TYPE
SIZE (Bytes) for TC++
SIZE (Bytes) for Windows/ Unix
char or signed char
1
1
unsigned char
1
1
int or signed int
2
4
unsigned int
2
4
short int or signed short int unsigned short int
2
2
2
2
long int or signed long int unsigned long int
4
4
4
4
float
4
4
double
8
8
10
10
long double
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Variables & Constants • Variable – a physical entity which can be changed E.g. height, weight, temperature etc.
• Constant – a physical entity which never changes E.g. pi value, number of days in a week etc.
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Variables • • •
All variables must be declared before being used. In C++ variables can be declared anywhere in the code. A variable may be initialized with a value while declaring it, by using the ‘=’operator
Naming rules: 6. The first character must be a letter or an underscore 7. Subsequent characters must be either letters, digits, or underscores. 8. Keywords , white spaces, punctuation marks or symbols not allowed
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Declaring variables Example: int x, y, z; char name=‘G’;
Syntax for declaration datatype v1, v2, v3, …………vn; datatype u1=value1,u2,u3=value2…;
where v1, v2, v3 are variable names.
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The ‘sizeof’ operator Consider the statements cout<<sizeof (int); cout<<sizeof x;
Syntax: sizeof (datatype); sizeof variableName;
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The Constants Types: integer, character, string, float. Integer Constants Integers are whole numbers. Default is decimal. Octal numbers preceded by a ‘ 0 ’. Hexadecimal numbers are preceded by a ‘ 0x ’. Long integers specified using ‘ l ’ after an integer
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The Constants
contd…
Character Constants: A single character is enclosed in single quotes. Some Escape sequence character constants: '\n' '\t' '\r' '\b' '\a' '\\' '\’'
new line horizontal tab carriage return backspace alert backslash apostrophe
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The Constants
contd…
String Constants : Sequence of characters enclosed in double quotes. A null terminated character automatically placed at the end of each string .
Float Constants: Used to represent floating numbers Consist of an integer part, a decimal point and a fraction part. Scientific notation can also be used.
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The Constants
contd…
1. /*Program to demonstrate use of constants*/ 2. int main ( ) 3. { 4. int num1=10; /*10 is an integer constant */ 5. double num2=28.5; /*28.5 is a floating point constant */ 6. char c = 'W'; /* ‘W’ is a character constant */ 7. cout<<"This is a constant string."; 8. cout<<"\nThe value of num1="<< num1; 9. cout<<"\nThe value of num2="<< num2; 10. cout<<"\nThe character "<
19
Defining Symbolic Constants Consider the statement: # define PI 3.14159
Syntax: # define symbolic_name value
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The Symbolic Constants 1. #define TEN 10 2. #define RNUM 28.5 3. #define CHARACTER 'C' 4. #define STRING "This is a constant string." 5. int main ( ){ 6. int num1 = TEN; 7. double num2 = RNUM; 8. char c = CHARACTER; 9. cout<<STRING; 10. cout<<"\nThe value of num1="<
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The Constant Variables • Variables of type (qualifiers) const cannot be changed by the program. • However, it can be given an initial value. • Used as a READ ONLY variable. Syntax: const datatype variable_name=value;
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The Operators Types: Arithmetic Assignment Relational Logical Bitwise
: + - ++ -- + - * / % : = , += -= *= /= %= : > < >= <= == != : && || ! : & | ^ << >> ~
Also classified into : Unary
: &(addr) *(indirect) +(sign) –(sign) ~(complement) !(NOT) ++(incre) --(decre) Binary : All other operators listed above Ternary : Conditional operator(? :)
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Increment and Decrement Operators An increment operator (++) adds 1 to its operand. A decrement operator (--) subtracts 1 from its operand. i ++; ++i; i --; --i;
/* i = i + 1 (post fixed) */ /* i = i + 1 (prefixed) */ /* i = i - 1 (post fixed) */ /* i = i - 1 (prefixed) */
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Special Assignment Operators The expression i = i + 5;
can also be written as i += 5;
/* Add 5 to i */
Similarly, i -= 5; i *= 5; i /= 5;
/* Subtract 5 from i */ /* Multiply i with 5 */ /* Divide i by 5 */
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Fahrenheit to Celsius conversion 1. #include 2. using namespace std; 4. int main( ) 5. { 6. int fahr=100, celsius; 7. celsius= 5*(fahr-32)/9; 8. cout<
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Logical operators 1. int main ( ){ 2. float f1, f2; 3. cout << "Enter a floating point number (f1)" << endl; 4. cin >> f1; 5. cout << "Enter another floating point number (f2)" << endl; 6. cin >> f2; 7. cout << "f1 > f2 is " << (f1 > f2) << endl; 8. cout << "f1 < f2 is " << (f1 < f2) << endl; 9. cout << "f1 == f2 is " << (f1 == f2) << endl; 10. cout << "f1 != f2 is " << (f1 != f2) << endl; 11. cout << "f1 >= f2 is " << (f1 >= f2) << endl; 12. cout << "f1 <= f2 is " << (f1 <= f2) << endl; 13. cout << "f1 && f2 is " << (f1 && f2) << endl; 14. cout << "f1 || f2 is " << (f1 || f2) << endl; Pragati Software Pvt. 15. }Ltd., 312, Lok Center, Marol-Maroshi Road, Marol, Andheri (East), Mumbai 400 059. www.pragatisoftware.com
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Loops and Conditions • Overview Selection if statement switch statement
Iteration while do while for
Control flow transfer statements break continue goto
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Selection Statements • Selection The if statement The switch statement
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The if statement Start
Statement1
True
If condition
Statement
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The if…else statement Start
Statement1
True
If condition
False Statement2
Statement3
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if construct if (i==3) cout<<“Hattrick!!”; if ( year_of_service>3) bonus=2500; if ((percentage>=40) && (percentage<50)) cout<<“Third division”;
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if construct -- different forms if(condition) Statement
if(condition) { Statements }
if(condition) Statement else Statement
if(condition) { Statements } else { Statements }
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if else
contd…
if(condition) { if(condition) Statement else Statement } else { if(condition) Statement else Statement }
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The if…else if ladder if(condition) { Statement } else if(condition) { Statement } else if(condition) { Statement } else { Statement }
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Conditional Operator Syntax: exp1 ? exp2 : exp3
If exp1 evaluates to true, then exp2 is returned else exp3 is returned
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Program to find vowel 1. int main( ) 2. { 3. char ch; 4. cout<<"\nEnter any character : "; cin>>ch; 5. if(ch=='a') cout<<"\n"<
37
Using the || operator 1. int main( ) 2. { 3. char ch; 4. cout<<"\nEnter any character : "; 5. cin>>ch; 6. if(ch=='a' ||ch=='e' || ch=='i'|| ch=='o' || ch=='u') 7. cout<
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The nested if-else 1. 2. 3. 4.
int main ( ) { int a=4,b=4; char ch; cout<<"Enter which operation u wish to perform"; cin>>ch; 5. if (ch == '+') a += b; 6. else if (ch == '-') a -= b; 7. else if (ch == '*') a *= b; 8. else if (ch == '/') a/=b; 9. else{ 10. cout<<"Error"; 11. return 1; 12. } 13. cout<<"Result is :"<
39
The switch statement Syntax: switch ( integer expression) { case constant1: statements; case constant2: statements; case constant3: statements; default: statements; }
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Using the switch-case The example for nested-if can be modified using switch- case as follows: switch (ch){ case '+' : a += b; break; case '-' : a -= b; break; case '*' : a *= b; break; case '/' : a /= b; break; default : cout<<"error"; }
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Program to find vowel using switch-case • • • • • • • • • • • • • • • •
int main( ){ char ch; cout<<"\nEnter any character : "; cin rel="nofollow">>ch; switch(ch) { case 'a': case 'e': case 'i': case 'o': case 'u': cout<
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Iteration • The while loop • The do-while loop • The for loop
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The while loop Start
while condition
false Exit loop
true statements
End
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The while loop Consider the statements while(i<=10) while(i>=1) while(i<=10 && j<=15)
Syntax: while (expression) statement;
while (expression) { statement1; statement2; }
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Using while • • • • • •
#include using namespace std; int main( ) { int i; i=1;
• • • • • • •
while(i<=10) { cout<<“\nValue of i is :”<
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Using while
Contd…
1. #include 2. using namespace std; 3. int main( ) 4. { 5. int num; 6. char another='y'; 7. while(another=='y') { 8. cout<<"Enter a number "; 9. cin>>num; 10. cout<<"square of "<>another; 13. } 14. }
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The do - while loop Start
statements
true
while condition
false
Exit loop End
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The do - while loop
Contd…
Syntax: do
do{ statement; while (expression);
statement1; statement2; } while (expression);
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Using do-while 1. #include 2. using namespace std; 3. int main( ) 4. { 5. int i; 6. i=1; 7. do 8. { 9. cout<<"\nValue of i is : "<
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The for loop Start
for condition
false Exit loop
true statements
End
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The for loop
Contd…
Consider the statements for(i=0;i<5;i++) for(i=10;i>=0;i--)
Syntax: for (exp1;exp2;exp3) { statement1; statement2; }
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Using for • • • • • • • • •
#include using namespace std; int main( ) { int i; for(i=0;i<=10;i++) cout<<"\nValue of i is : "<
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Nesting of for loop 1. #include 2. using namespace std; 3. int main( ) 4. { 5. int i,j; 6. for (j=1;j<=12;j++) 7. { 8. for (i=1; i<=10;i++) 9. { 10. cout<
54
Control Flow Transfer Statements
break; continue; goto labelName;
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Using ‘break’ • • • • • • • • • • • • •
#include using namespace std; int main( ) { int i; for(i=1;i<=20;i++) { if(i%14==0) break; cout<<<"\n"; } return 0; }
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Using ‘continue’ • • • • • • • • • • • • •
#include using namespace std; int main( ) { int i; for(i=1;i<=20;i++) { if(i%2!=0) continue; cout<<"\nValue of i is : "<
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Using ‘goto’ • • • • • • • • • • • • •
#include using namespace std; int main( ) { cout<<"\nhello 1"; cout<<"\nhello 2"; goto a; cout<<"\nhello 3"; cout<<"\nhello 4"; a: cout<<"\nhello 5"; return 0; }
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Type Conversion Implicit Conversion: In C+ +, the following program code is valid, and will result in proper evaluation: int i, j; char k; ... i = j + k;
The type of the variable k is converted from char to int, and then used in the expression.
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Implicit Conversion 1. 2. 3. 4. 5. 6. 7. 8.
#include using namespace std; int main( ) { float result = 4 / 3; cout<
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Explicit Conversion Consider the following program code: long i; int j, k; i = j + k;
Explicit casting : i = (long) j + k;
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Explicit Conversion 1. 2. 3. 4. 5. 6. 7. 8.
contd…
#include using namespace std; int main( ) { float result= (float) 4/3; cout<<"Result = "<
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Module 2: Arrays • Overview Definition Array of integers and characters Initialization of arrays String manipulation functions Multidimensional Arrays
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Arrays • Collection of variables of
Similar data type Referred by a common name Stored in consecutive memory locations Array values can be accessed via its subscript
e.g. int marks[5];
Syntax: datatype ArrayVariableName[ number of elements] ;
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Array example • • • • • • • • • • • • • • • • •
#include using namespace std; # define MAX_VALS 4 int main ( ){ int values[4] ,i, j, sum=0; cout<<"Enter 4 values...."; for(i = 0; i<MAX_VALS;i++) { cin>>j; values [i] = j ; sum += j; } cout<<"\n values were : "; for (i = 0 ; i < MAX_VALS; i++) cout<<"\n"<
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Arrays of Characters 1. #include 2. using namespace std; 3. # define MAX 5 4. int main( ) 5. { 6. char str[MAX]; 7. int i; 8. cout<<"Enter 5 characters"<<endl; 9. for (i = 0; i < MAX; i++) 10. cin>>str[i]; 11. cout<<"\nThe characters were: "; 12. for (i = 0; i < MAX; i++) 13. cout<<str[i]; 14. return 0; 15. }
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The ‘cin’ and strings 1. #include 2. using namespace std; 3. #define MAX 10 4. int main( ) 5. { 6. char str[MAX]; 7. cout<<"Enter a string: "; 8. cin>>str; 9. cout<<str<<"\n"; 10. return 0; 11. }
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Initialisation of Arrays int score[11] = {89,125,56,45}; Index number Or subscript
Values
0
1
2 3
4
5
score 89 125 56 45 0 0 100
102
104
106
108 110
6 0
7 0
112 114
8
9 10
0 116
0 118
0 120
Memory locations ArrayName Pragati Software Pvt. Ltd., 312, Lok Center, Marol-Maroshi Road, Marol, Andheri (East), Mumbai 400 059. www.pragatisoftware.com
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Char Arrays or Strings
char name[10]=“Rosy”;
0
1
2
3
4
R o
s
y
\0
100
101 102
5
6
7
8
103 104 105 106 107 108
9
109
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Some string manipulation functions strlen ( ) strcpy ( ) strcat ( ) strcmp ( )
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Some string manipulation functions Syntax: int strlen (const char *source); char *strcpy(char *destination, const char *source); char *strcat(char *Destination, char *Source); int strcmp (const char *string1, const char *string2);
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Using string functions • • • • • • • • • • • • • • •
#include<string.h> int main( ){ char str1[20]="C ",str2[20]="Programming in ",str3[30]=""; cout<<"Length of str1 is "<<strlen(str1); strcat(str2,str1); //append str1 at the end of str2 cout<<"\nstr2 is "<<str2; strcat(str3,str2); strcat(str3,"language"); cout<<"\nlength of "<<str3<<" is "<<strlen(str3); if( strcmp("apple","Apple")>0) cout<<"\nfirst string is greater"; else if ( strcmp("apple","Apple")<0) cout<<"\nsecond string is greater"; else cout<<"\nboth strings are equal“;
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Multi-Dimensional Arrays Consider the statement int student[5][2];
Syntax: datatype variableName [index1]….[indexn] The 3rd element from the 1st row can be accessed by, student[2][1]
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A double dimensional array 1. int main( ){ 2. int total=0,i,j,col=1,row=2; 3. int score[3][11]= { 4. {95,25,56,45,75}, 5. {14,22,88,37,95,12}, 6. {84,25,16,23,6,89,12,34} 7. }; 8. for(i=0;i<3;i++) { 9. cout<<"Test: "<
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74
Strings char days[7][10]={ “Monday”, “Tuesday”, “Wednesday”, “Thursday”, “Friday”, “Saturday”, “Sunday” };
Index
100
0
M o
n
d
a
y
\0
1
T u
e
s
d
a
y
\0
2
W e
d
n
e
s
d
a
y
3
T h
u
r
s
d
a
y
\0
4
F
r
i
d
a
y
\0
5
S
a
t
u
r
d
a
6
S
u
n
d
a
y
\0
110
\0
120
Memory Locations
130 140
y
\0
150 160
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75
Printing the array of strings 1. int main( ){ 2. char month[10]="May"; 3. char days[7][10]={ 4. "Monday", 5. "Tuesday", 6. "Wednesday", 7. "Thursday", 8. "Friday", 9. "Saturday", 10. "Sunday" 11. }; 12. cout<<"\nMonth is : "<<month; 13. for(int i=0;i<7;i++) 14. cout<<" \n Day is :"<
76
Module 3: Functions • Overview Definition User defined functions Storage Classes Recursion Default Arguments Function Overloading Inline functions Scope Resolution operator
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Functions • Set of statements written in a separate body • To perform a distinguishable task • Functions are classified into 1) Library or built-in functions 2) User defined functions
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Library functions • Library or built-in functions eg. strcpy( ), strcat( )
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The User defined functions • Syntax: return_type function_name (argument list) argument declarations { declarations; executable statements; }
Eg: int show_age(int age ); int cal_age(char );
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80
Creating a user defined function Function header or function prototype Return type
Function name
int isEven value)
Formal Parameter list (int
{ if(value % 2 == 0) return 1; else return 0; }
Function body
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Function types • Without argument & without return value void clrscr(void);
• With argument but no return value void gotoxy(int x, int y);
• With argument & with return value int abs(int num);
• Without argument but with return value int getchar( );
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82
Program to compute power of an integer 1. int power (int,int); 2. int main ( ){ 3. int i; 4. for (i = 0; i < 10; i++) 5. cout<<<"\t"<<power(2, i)<<"\t"<<power (3, i)<<endl; 6. return 0; 7. } 8. int power(int base,int n){ 9. int i, p; 10. p = 1; 11. for (i = 1; i <= n; i++) 12. p *= base; 13. return p; 14. } Pragati Software Pvt. Ltd., 312, Lok Center, Marol-Maroshi Road, Marol, Andheri (East), Mumbai 400 059. www.pragatisoftware.com
83
Classification of variables Based on the position of declaration in the program Storage class. Based on position Local Global
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Scope of variables Local variables
Global variables
Declared within any function body
Declared outside of any function body
Available only within declaring function
Available to the entire program, hence can be shared by other functions
Are lost as soon as the declaring function body terminates • void fun( ) • { • int i=10; /*local to fun */ • } • void foo( ) • { • int i=10; /*local to foo */ • }
Are lost as soon as the declaring application or program terminates • int k=10; /* global to prg */ • void fun( ) • { • int i=10; k=35; • } • void foo( ) • { • int i=10; cout<
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85
Storage Classes The storage class gives the following information about the variable: Where it is stored Its initial value Scope of variable Lifetime of the variable i.e. how long it exists
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86
Automatic Keyword : auto Locations : Memory Initial Value: Garbage Scope : Only in the function or block in which it is declared Lifetime : Only in the function or block in which it is declared Example : auto int num1;
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Register Keyword : register Locations : Register Initial Value: Garbage Scope : Only in the function or block in which it is declared Lifetime : Only in the function or block in which it is declared Example : register int num1;
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Static Keyword : static Locations : Memory Initial Value: 0 Scope : Only in the function or block in which it is declared Lifetime : From the point of declaration to the end of the program Example : static int num1;
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Difference between auto and static variables 1. #include 2. using namespace std; 4. void inc( ); 5. void inc_i( ); 7. int 8. { 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. }
main( ) cout<<"Invoking function inc( )...."; inc( ); inc( ); inc( ); cout<<"Invoking function inc_i( )...."; inc_i( ); inc_i( ); inc_i( ); return 0;
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90
Difference between auto and static variable • • • • •
void inc( ){ int i=0; /* auto variable */ i++; cout<<"\nValue of i:"<
• • • • •
void inc_i( ){ static int i; /* static variable */ i++; cout<<"\nValue of i:"<
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Extern Keyword : extern Locations : Memory Initial Value: last value attained in a previous file Scope : global Lifetime : global Example : extern int num1;
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Example of extern 1. /* Source file F04GlobalVar.cpp */ 2. int n = 3; 3. void alter ( ); 4. int main ( ) 5. { 6. cout<< n; 7. alter( ); 8. cout<< n; 9. return 0; 10. }
1. /* Source file F04ExternExample.cpp */ • • • • •
extern int n; void alter ( ) { n = 10; }
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Making Data and Functions Private static int array [MAX]; int array2 [20]; int main ( ) { ... } static int privatefun ( ) { ... } double publicfun ( ) { ... } Pragati Software Pvt. Ltd., 312, Lok Center, Marol-Maroshi Road, Marol, Andheri (East), Mumbai 400 059. www.pragatisoftware.com
94
Recursion • Function makes a call to itself • Repeatedly invokes itself until a condition is met • Hence must have a return statement to exit
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95
Finding factorial using recursion 1. #include 2. using namespace std; 3. int factorial(int x) { 4. if(x==1) 5. return 1; 6. else 7. x=x*factorial(x-1); 8. return x; 9. } 10. int main( ) { 11. int num; 12. num = factorial(5); 13. cout<<"\nFactorial of 5 is "<
96
Default Arguments Eg: cin.ignore(1); & cin.ignore(4,’\n’); square(6); & square(6, 10);
Syntax: return_type func_name( arg1, arg2, …., argn = value){ //executable statements; }
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Using default arguments • • • • • •
int add(int,int=0); int main( ){ cout<
• • •
int add(int x,int y){ return x+y; }
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Function overloading void void void void
max (int, int); max (float, float); max (char , char); max (int, int, int);
Function calls will be: max(87, 65); max( 35.5f, 76.6f); max( ‘J’, ‘L’); max(45, 90, 23);
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99
Using function overloading 1. void add(int x,int y){ cout<<x+y<<endl; 2. } 3. void add(float x,float y) { cout<<x+y<<endl; 4. } 5. void add(int x,float y){ cout<<x+y<<endl; 6. } 7. void add(float x,int y){ cout<<x+y<<endl; 8. } 9. int main( ){ 10. add(10,10); 11. add(30,20.15f); 12. add(16.57f,4); 13. add(3.25f,6.44f); 14. return 0; 15. }
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Ambiguity 1. void add(int x,int y=15){ 2. cout<<x+y<<endl; 3. } 4. void add(int x,int y){ 5. cout<<x+y<<endl; 6. } 7. int main( ){ 8. add(13); 9. add(10,10); 10. return 0; 11. }
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Inline functions • To avoid the run-time overhead when using functions Eg: inline int min (int v1,int v2){ return (v1 < v2 ? v1 : v2 ); }
• Syntax inline return_type function_name (argument_list){ //executable statements; }
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Scope Resolution operator (::) 1. • • • • • • •
int count = 0; int main(void) { int count = 0; ::count = 1; // set global count to 1 count = 2; // set local count to 2 return 0; }
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103
Module 4: Pointers and References • Overview Definition and declaration Pointer to an array Pointer arithmetic Pointers as function arguments Array of pointers Pointer to pointer Command line arguments Function pointers References in C++
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104
Pointer • Variable which holds a only memory address pointer variable = 65524
Name
Num
Value
189
Memory address
65524
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105
Pointer declaration
datatype *pointerVariableName; pointer declaration Type of that variable whose address will be stored by the pointer
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106
Pointer declaration & initialization Syntax for Initialization : pointerVariableName = & variable; Address Of
Declaration-cum-Initialization datatype *pointerVariableName = &variable;
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Pointer example 1. int main( ) { 2. int x=10,y=20,z=30; 3. int *ptr = &x; 5.
cout<<"Value of x:"<<x<<endl; 6. cout <<"Value at *ptr:"<<*ptr<<endl; 7. cout <<"Value at &x:"<<*&x<<endl<<endl;
65514 65516 65518
65520
9.
cout <<"Address of x:"<<(unsigned)( &x)<<endl; 10. cout <<"Address pointed by the pointer:"<<(unsigned)ptr<<endl ;
65522
65524
65524
ptr
30
z
20
y
10
x
12. cout<<"Changing the contents at address pointed by ptr... Pragati Software Pvt. Ltd., 312, Lok Center, Marol-Maroshi Road, Marol, Andheri (East), Mumbai 400 059. www.pragatisoftware.com
108
Pointer example
contd…
1. cout<<"Changing the ptr address ... "<<endl; 2. ptr=&y; 3. cout<<"Value of y:"<
65514
65516
6. cout <<"Address of x:"<<(unsigned)(&y)<<endl; 7. cout <<"Address pointed by the pointer:"<<(unsigned)ptr<<endl; 8. 9. cout<<"The size of the pointer is:"<<sizeof(ptr)<<endl; 10. return 0; 11. }
65518
65524
ptr
30
z
65522
20
y
65524
10
x
65520
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109
Pointer to an Array 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11.
int main ( ){ int ary[5]={10,20,30,40,50}; int *ptr, i; for(i=0;i<5;i++){ ptr=&ary[i]; cout<<*ptr<<'\t'; } cout<< endl<<"Size of pointer:"<<sizeof(ptr); cout<<endl<< "Size of array:"<<sizeof(ary)<<endl; return 0; 0 1 2 3 4 }
ary 10 20 30 40 50 100
102 104 106
108
110
ptr 100 Pragati Software Pvt. Ltd., 312, Lok Center, Marol-Maroshi Road, Marol, Andheri (East), Mumbai 400 059. www.pragatisoftware.com
110
Pointer arithmetic • Operations allowed on pointers Pointer and integer addition Pointer and integer subtraction Pointer and pointer subtraction Pointer and pointer relational operations
• Operations NOT allowed on pointers Pointer and pointer addition All division and multiplication operations
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111
Pointer addition • ptr++ or ptr-- : Increments or decrements the pointer by the size in bytes depending upon the data for which pointer is declared
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Accessing array elements using pointers Hence, the previous program can also be written as: 3. int main( ){ 4. int ary[5]={10,20,30,40,50}; 5. int *ptr= ary; 6. for(;ptr<&ary[5];ptr++) 7. cout<<*ptr; 8. return 0; 9. }
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113
Pointers to Character Strings 1. void copy_string (char *from, char *to) 2. { 3. for ( ; *from != '\0'; ++ from, ++ to) 4. *to = *from; 5. *to = '\0'; 6. }
Or, better still: 8. void copy_string (char *from, char *to) 9. { 10. while (*from) 11. *to ++ = *from ++; 12. *to='\0'; 13. }
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Pointer subtraction 1. 2. 3. 4. 5. 6. 7.
int main( ){ int ary[5]={10,20,30,40,50}; int *ptr,*ptr1=ary; for(ptr=ary;ptr<&ary[5];ptr++){ cout<<*ptr; } cout<<“Number of elements in the array are:”<
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Example of pointer subtraction 1. 2. 3. 4. 5. 6. 7. 8.
/* Function to find the length of a string. */ int str_len (char *s) { char *p = s; while (*p != '\0') p ++; return (p - s); }
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Pointers as function arguments • Two methods to call a function with arguments Call by Value Call by reference
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117
Pass by value • • • • • • • •
int main( ) { void swap(int, int); int x=10, y=20; cout<<x<<‘\t’<
• • • • • •
void swap(int num1, int num2) { int temp; temp=num1; num1=num2; num2=temp; }
// 10 20 // 10 20
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118
Pass by address • • • • • • • • • • • • • •
int main( ) { void swap(int*, int*); int x=10, y=20; cout<<x<<‘\t’<
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119
Pass by value vs. Pass by address main( )
main( )
x
y
x
y
10
20
10
20
65510
65512
65510
65512
swap(x,y); swap(int x, int y)
swap(&x,&y); swap(int *x, int *y)
x
y
x
y
10
20
65510
65512
65524
65526
65524
65526
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120
Arrays of Pointers Examples: char *argv[4];
Syntax: datatype *pointerName[arraySize];
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121
Array of pointers • • • • • • • • • • • •
int main ( ) { int num1 = 1, num2 = 2, num3 = 3; int i; int *iptr [3]; iptr [0] = &num1; iptr [1] = &num2; iptr [2] = &num3; for (i = 0; i < 3; i ++) cout<< *iptr [i]; return 0; }
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122
Array of pointers int main( ) { int ary1[3]={10,20,30}; int ary2[5]={2,4,6,8,10}; int ary3[7]={8,16,32,64,128,256,512},i; int *ptr[3]; //collection of 3 pointers in an array ptr[0]=ary1; ptr[1]=ary2; ptr[2]=ary3; for(i=0;i<3;i++) cout<<(ptr[0]+i) ; cout<< endl; for(i=0;i<5;i++) cout<<(ptr[1]+i) ; cout<< endl; for(i=0;i<7;i++) cout<<(ptr[1]+i) ; cout<< endl; return 0; } Pragati Software Pvt. Ltd., 312, Lok Center, Marol-Maroshi Road, Marol, Andheri (East), Mumbai 400 059. www.pragatisoftware.com
123
Array of pointers to character strings int main ( ) { int num; cout<<“Enter month number "; cin rel="nofollow">>num; cout<<"The month name is :“<<month (num) ; return 0; } char *month (int n) { char *name[ ] = {"Illegal month", "January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December" }; return ( (n < 1 || n > 12) ? name [0] : name [n] ); }
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124
Pointer to pointer int main( ) { int x=10; int *ptr1=&x;
65516
int **ptr2 = &ptr1;
65518
int ***ptr3 = &ptr2; cout<<***ptr3; return 0; }
65514
65520 65522
65524
65520
ptr3
65522
ptr2
65524
ptr1
10
x
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125
Command Line Arguments
Syntax
main( int argc, char * argv [ ])
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126
Accessing command line parameters /* Program to type command line strings */ int main (int argc, char *argv [ ] ) { int i; for (i = 1; i < argc; i ++) cout<<“arg “<<<“is :“<< argv [i] ; }
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127
Function pointers void show1(char x, char y) { cout<<"\n Characters : “<<x<<“ & ”<
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128
References Eg: int i; int &x=i;
Syntax: data_type & reference_variable = variable;
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129
Swapping two integers with references • void swap(int &int1,int &int2){ • int temp = int2; • int2 = int1; • int1 = temp; • } • int main( ) { • int num1 = 10; • int num2 = 20; • cout<<"Before swap:\tnum1: "<
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130
Using References 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20.
int look_up (const int *array, int size, int value, int &occurs){ int index = -1; for (int ix = 0; ix < size; ++ix) if(array [ix] == value){ if (index == -1) index = ix; ++occurs; } return index; } int main( ){ int arry[]={10,24,10,35,62,10,24},no_elements=0; int position=look_up(arry,(sizeof arry)/(sizeof(int)),35,no_elements); if(position==-1) cout<<"Number is not in the array"<<endl; else{ cout<<"Position:"<<position<<endl; cout<<"No of occurances:"<<no_elements<<endl; } return 0; }
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131
Module 5:Classes and Objects • Overview
Classes and Objects this pointer Constructors Dynamic Memory Allocation Destructors static Data Members and Member Functions const Functions
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Classes • Classes are user defined data types • Syntax class tag_name { private: // --- member variables & functions protected: // --- member variables & functions public: // --- member variables & functions };
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133
Using class declaration • • • • • • • • • • • • •
class BankAccount { //default access is private. unsigned acc_num; double balance; void deposit(double amt){ balance+=amt; } void withdraw(double amt){ balance-=amt; } void display( ){ cout<<"Account NUMBER-"<
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134
Access Specifiers • private : Members are accessible within the class only. They are not inherited by the derived class. • public :
Members are accessible anywhere. They are also inherited by the derived classes.
• protected : Members are accessible in the class itself & also inherited by the derived classes
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135
Using Access Specifiers • class BankAccount { //default access is private. • unsigned acc_num; • double balance; • public: • void deposit(double amt){ • balance+=amt; • } • void withdraw(double amt){ • balance-=amt; • } • void display( ){ • cout<<"Account NUMBER-"<
136
Using the member functions 1. int 2. { 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. }
main( ) BankAccount ba; ba.display( ); ba.deposit (5000); cout<<"Balance after depositing Rs.5000/- :"; ba.display( ); ba.withdraw(1000); cout<<"Balance after withdrawing Rs.1000/- :" ; ba.display( ); return 0;
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137
Scope Resolution operator & class members 1. 2. 3. 4. 5. 6. 7. 8.
#include using namespace std; class X { public: int count; }; int X::count = 10; // define data member
10. 11. 12. 13. 14.
int main ( ) { int X = 0; // hides class type X cout << X::count << endl; // use member of class X return 0; }
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Defining member functions using operator :: 1. 2. 3. 4. • • • •
class BankAccount { unsigned acc_num; double balance; public: void setdata ( unsigned , double) void deposit(double); void withdraw(double); void display( ); };
• • •
void BankAccount :: withdraw(double amt) { balance-=amt; }
• • •
void BankAccount :: deposit(double amt) { balance+=amt; }
• •
void BankAccount :: display( ) { cout<<"Account NUMBER-"<
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this pointer void BankAccount :: setdata ( unsigned acc_num, double balance) { this → acc_num = acc_num; this → balance = balance; }
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Constructors • Automatic initialization done with special member function called Constructors i.e., • Constructor is executed automatically whenever an object is created. • Constructors have, Same name as class No return type • Constructors can take arguments • Constructors can be overloaded
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Constructors • Syntax to declare a constructor class_name (argument_list); •
Syntax to define a constructor class_name::class_name(argument_list){ // body of constructor function; }
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Types of Constructors • • • •
Default constructor Parameterized constructor Constructors with default arguments Copy constructors
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Default Constructors • Syntax class name{ public: name( ){ // executable statements; } };
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Default Constructors • • • •
Contd …
BankAccount ( ) { constructor min_bal = 5000; acc_num = 2004; }
// default
Using the member initialization list : 5. BankAccount ( ) : min_bal( 5000 ) , acc_num( 2004 ) 6. { }
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Parameterized constructor (unsigned x) : min_bal ( 5000 ) , acc_num ( x ) { }
BankAccount
(double bal,unsigned x) : min_bal (bal) , acc_num(x) { }
BankAccount
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Constructor Overloading • class BankAccount { //default access is private. • unsigned acc_num; • double balance; • public: • BankAccount( ):balance(5000),acc_num(2004) • {} • BankAccount(unsigned x):balance(5000),acc_num(x) • {} • BankAccount(double bal,unsigned x):balance(bal),acc_num(x) • {} • void deposit(double amt){ • balance+=amt; • } • void withdraw(double amt){ • balance-=amt; • } • void display( ){ • cout<<"Account NUMBER-"<
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Constructor Overloading
Contd …
• • • •
int main( ){ BankAccount B1; B1.deposit(3500); B1.display( );
•
BankAccount B2(3005); //BankAccount B2=3005; B2.deposit(8000); B2.display( );
• • • •
return 0; }
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Constructors with default arguments • • • • • • •
//BankAccount (unsigned x):balance(5000),acc_num(x) //{ } //BankAccount (double bal, unsigned x): balance ( bal ), acc_num (x) //{ } BankAccount (unsigned x ,double bal=5000):balance(bal),acc_num(x) {}
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Explicit keyword • • • • • • •
#include using namespace std;
class BankAccount{ unsigned acc_num; double balance; public: explicit BankAccount ( unsigned x ): balance ( 5000 ), acc_num (x) • {} • bool compare_bal ( BankAccount s ){ return s.balance > balance; } • void deposit(double amt){ • balance+=amt; • } • void withdraw(double amt){ • balance-=amt; • } • void display(){ • cout<<"Account NUMBER-"<
Explicit keyword
Contd …
1. int main( ){ 2. BankAccount B2=3005; //error 3. B2.deposit(8000); 4. cout<<"\nB2 details...."<<endl; 5. B2.display( ); 7. 8. }
return 0;
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Copy constructor • Used to declare and initialize an object from another object Syntax to declare: class_name ( class_name &); Syntax to invoke c’tor: class_name new_object = source_object; OR class_name new_object(source_object); Pragati Software Pvt. Ltd., 312, Lok Center, Marol-Maroshi Road, Marol, Andheri (East), Mumbai 400 059. www.pragatisoftware.com
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Copy constructor example • • • • • • • • • • • • • • • • • • •
class BankAccount{ unsigned acc_num; unsigned balance; public: BankAccount():balance(5000),acc_num(2004) {} BankAccount(BankAccount &obj):balance(obj.balance),acc_num(2005) {} void deposit(unsigned x){ balance+=x; } void withdraw(unsigned x){ balance-=x; } void display( ){ cout<<"Account NUMBER-"<
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Copy constructor example • • • • •
Contd …
int main( ){ BankAccount B1; cout<<"\nB1 deposits 3500\n"; B1.deposit(3500); B1.display( );
• • •
BankAccount B2(B1); // invoking copy ctor cout<<"\nB2 cloned B1...."<<endl; B2.display( );
• • •
cout<<"\n"; return 0; }
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Dynamic Allocation • Used to allocate memory to objects at runtime • Memory can be allocated using the new operator Eg: int *pi=new int; int *pia = new int[10]; LinkList *ptr = new LinkList( );
• Memory can be de-allocated using the delete operator delete ptr
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Dynamic Allocation
Contd …
1. class BankAccount 2. { 3. unsigned acc_num; 4. double balance; 5. public: 6. BankAccount(unsigned x,double bal) : acc_num ( x ), balance ( bal ) 7. {} 8. void display( ) 9. { 10. cout<
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Dynamic Allocation • • • • • • •
Contd …
int main( ) { BankAccount *ptr=new BankAccount(333,3500); ptr- rel="nofollow">display( ); delete ptr; return 0; }
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Destructors • Automatically called when an object is destroyed . • Syntax class name{ public: name( ){ // executable statements; } ~name( ){ // executable statements; } }; Pragati Software Pvt. Ltd., 312, Lok Center, Marol-Maroshi Road, Marol, Andheri (East), Mumbai 400 059. www.pragatisoftware.com
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Destructors Example • • • • • •
class BankAccount { unsigned acc_num; double balance; public: BankAccount( unsigned x, double bal) : acc_num ( x ) , balance( bal ) • { } • ~BankAccount( ) • { • cout<<"This is the bank account destructor!"<<endl; • } • void display( ){ • cout<
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Destructors Example
Contd…
1. int main( ) 2. { 3. cout<<"For object created on the heap..."<<endl; 4. BankAccount *ptr=new BankAccount(333,3500); 5. delete ptr; 7. 8. 9. 10. }
cout<<endl<<"For temporary object"<<endl; BankAccount B1(334,4500); return 0;
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Static Data Members Syntax to declare: static data-type data_member;
Syntax to assign a value: Outside the class: data-type ClassName :: data_member = value;
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Static Member functions • Can access only other static members of the same class Syntax to declare: return_type static function_name(argument_list) ; Syntax to access: object::function_name(argument_list);
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Static Data Members and Member Functions Example • • • • • • • • • • • • • • • • • • • •
class BankAccount { unsigned acc_num; double balance; static int num; public: BankAccount ( ){ acc_num=450; balance=5000.0; ++num; } BankAccount ( unsigned x, double bal){ acc_num=x; balance=bal; ++num; } void deposit ( double amt){ balance+=amt; } static void showNoObjects( ){ cout<<"\nThe total number of objects created are:"<
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Static Data Members and Member Functions Example • • • • •
void display( ){ cout<<"\nAccount NUMBER-"<
• • • •
int main( ){ BankAccount S1; S1.deposit( 3500 ); S1.display( );
•
BankAccount S2(451,3005); // BankAccount S2=3005; • S2.deposit( 8000 ); • S2.display( ); • BankAccount::showNoObjects( ); • cout<<endl; • return 0; Pragati • Software } Pvt. Ltd., 312, Lok Center, Marol-Maroshi Road, Marol, Andheri (East), Mumbai 400 059. www.pragatisoftware.com
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Const Objects and const Member functions • • • • • • • • • • • • • • • • • •
class Time{ int hr,min,sec; public: Time(int h,int m,int s) { hr=h; min=m; sec=s; } void setTime(int h,int m,int s) { hr=h; min=m; sec=s; } void display( ) const { cout<<endl<<"the time is:"; cout<
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Const Objects and const Member functions •
Time const noon (12,0,0 ) ; object
• • • • • • •
int main( ) { noon.display( ); noon.setTime(5,6,7); cout<<endl; return 0; }
//Const
//will be an error ;
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Mutable keyword • • • • • • • • • • • • • • • • • • •
•
class Time{ int hr, min, sec; mutable int hr1; public: Time (int h , int m ,int s){ hr=h; min=m; sec=s; } void setTime (int h, int m, int s) { hr=h; min=m; sec=s; } void display( ) const { hr1 = 2; cout<<endl<<"The time is:"; cout<
};
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Module 6: Friend keyword • Overview Friend Functions Friend Classes
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Friend functions • Used to access the private members of a class by nonmember functions Syntax for declaring: friend return_type function_name(argument list); Syntax for defining: function_name(argument list){ // Body of function } Syntax for calling: function_name(argument list); Pragati Software Pvt. Ltd., 312, Lok Center, Marol-Maroshi Road, Marol, Andheri (East), Mumbai 400 059. www.pragatisoftware.com
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Friend functions example • • • • • • • • • • • • • • • • • •
class Time{ int hr,min,sec; friend Time calculateTime(Time,Time); public: Time( ) { hr=0; min=0; sec=0; } Time(int hr1,int min1,int sec1) { hr=hr1; min=min1; sec=sec1; } void display( ){ cout<
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Friend functions example •
contd…
• • • • • • • •
//function calculateTime requires to access the private members of class Time Time calculateTime (Time t1,Time t2) { Time result; result.hr=t1.hr+t2.hr; result.min=t1.min+t2.min; result.sec=t1.sec+t2.sec; return result; }
• • • • • • • •
int main( ) { Time t1(3,3,5), t2(2,5,6) ; Time t3; t3=calculateTime(t1,t2); t3.display( ); return 0; }
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Friend classes • • • • • • • • • • • • • •
class Node{ int x; friend class LinkedList; public: Node( ) : x(100) {} }; class LinkedList { Node obj; public: void display( ){ cout<<"the value of x is:"<
• • • • • •
int main( ) { LinkedList ll; ll.display( ); return 0; }
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Module 7: Operator Overloading • Overview Overloading The Binary + operator Overloading The prefix operator Overloading The postfix operator
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Operator overloading • Facility to give mutiple meaning to the set of predefined operators. • Syntax for declaring return_type operator operator_symbol(argument_list);
• Syntax for defining return_type operator operator_symbol(argument_list){ }
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Operator Overloading • The following operators can be overloaded: + ^ += < rel="nofollow"> &&
= -= <= ||
* < & >= ++
/ > new << --
% != delete >> ()
Following operators cannot be overloaded: sizeof, . , :: , ?: Pragati Software Pvt. Ltd., 312, Lok Center, Marol-Maroshi Road, Marol, Andheri (East), Mumbai 400 059. www.pragatisoftware.com
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Operator Overloading • Operator Overloading can be done by two methods: As a member function As a friend function
• No of parameters a Unary operator takes If declared as a member function is none If declared as a friend function is one
• No of parameters a Binary operator takes If declared as a member function is one If declared as a friend function is two
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Overloading the Plus operator as a Member function
1. class Time{ 2. int hr, min, sec; • Time 3. public: operator+(Time t2) 4. Time( ) • { 5. { • Time result; 6. hr=0; • result.hr=hr+t2.hr; 7. min=0; • 8. sec=0; result.min=min+t2.mi 9. } n; 10. Time (int hr, int min, int • sec) { result.sec=sec+t2.sec 11. this->hr=hr; ; 12. this->min=min; • return result; 13. this->sec=sec; • } 14. } • }; 15. void display( ) { 16. cout<
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Overloading the Plus operator as a Friend function
• class Time{ • int hr, min, sec; • Time operator+(Time • public: t1,Time t2) • Time( ){ • { • hr=0; • Time result; • min=0; • result.hr=t1.hr+t2.hr; • sec=0; • • } result.min=t1.min+t2.mi • Time( int hr, int min, int n; sec){ • • this->hr= hr; result.sec=t1.sec+t2.sec; • this->min= min; • return result; • this->sec= sec; • } • } • void display( ){ • cout<
Operator Overloading Example The call for both methods: • • • • • • • • •
int main( ) { Time t1(3,3,5),t2(2,5,6); Time t3; t3=t1+t2; //this invokes the operator overloaded function t3.display(); cout<<endl; return 0; }
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Overloading the Prefix operator as a Member function
1. class Time{ • Time 2. int hr, min, sec; operator++( ) 3. public: • { 4. Time( ) • Time result; 5. { • result.hr=++hr; 6. hr=0; • 7. min=0; result.min=++min; 8. sec=0; • 9. } result.sec=++sec; 10. Time (int hr, int min, int sec) { • return result; 11. this->hr=hr; • } 12. this->min=min; • }; 13. this->sec=sec; 14. } 15. void display( ){ 16. cout<
Overloading the Prefix operator as a Friend function • • • • • • • • • • • • • • • • • •
class Time{ int hr, min, sec; public: Time( ){ hr=0; min=0; sec=0; } Time( int hr, int min, int sec){ this->hr= hr; this->min= min; this->sec= sec; } void display( ){
cout<
• • • • • • • •
Time operator++ (Time t) { Time result; result.hr=++t. hr; result.min=++t. min; result.sec=++t. sec; return result; }
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Operator Overloading for prefix operator Example The call for both methods: • • • • • • • • •
int main( ) { Time t2(2,5,6); Time t3; t3=++t2; //this invokes the operator overloaded function t3.display( ); cout<<endl; return 0; }
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Postfix operator overloaded As a member function: • • • • • • •
Time operator++ ( int){ Time result; result. hr= hr++; result. min= min++; result. sec= sec++; return result; }
As a friend function: • • • • • • •
Time operator++ (Time t, int){ Time result; result. hr=t. hr++; result. min=t. min++; result. sec= t. sec++; return result; }
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Module 8: Inheritance • Overview
Inheritance Access Specifier Single Inheritance Multiple Inheritance Hybrid Inheritance
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Inheritance • Creating a new class from an existing class • Syntax: class derived_class_name: access specifier baseClass_name { …… };
• Syntax for Multiple Inheritance class derived_class_name: access specifier baseClass1_name, access specifier baseClass2_name, … { …… Pragati Software Pvt. Ltd., 312,}; Lok Center, Marol-Maroshi Road, Marol, Andheri (East), Mumbai 400 059. www.pragatisoftware.com
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Inheritance Access Specifier Type of Access Specifier private
PRIVATE MEMBERS
PROTECTED MEMBERS
PUBLIC MEMBERS
Not Inherited
Inherited but become private members of derived class
Inherited but become private members of derived class
protected
Not inherited
Inherited but remain protected members of derived class
Inherited but become protected members of derived class
public
Not inherited
Inherited but remain protected members of derived class
Inherited but become public members of derived class
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Types of inheritance • • • •
Single Multilevel Multiple Hybrid
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Single Inheritance: The Base Class • • • • • • • • • • • • • • •
class BankAccount{ protected: int accNo; double balance; public: BankAccount( ) { accNo=0; balance=5000; } void display( ) { cout<<"Account Number:"<
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Single Inheritance
Contd…
1. int main( ) 2. { 3. SavingAccount S1(8.75f); 4. S1.display( ); 6. 7. }
return 0;
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Constructor Ordering 1.
SavingAccount S1(8.75f);
3. • • • •
class BankAccount { BankAccount( ) { accNo=0; balance=5000; } };
• • • • •
class SavingAccount : public BankAccount { SavingAccount(float rofI) { rateOfInterest=rofI; } };
invokes
invokes
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Constructor Ordering • • • • • • • • • • • • • • • • • •
contd…
class BankAccount{ protected: int accNo; double balance; public: BankAccount(int AccNO,double bal) { accNo=AccNO; balance=bal; } }; class SavingAccount : public BankAccount { float minimumBalance; float rateOfInterest; public: SavingAccount(int AccNO,double bal,float rofI):BankAccount(AccNO,bal) { rateOfInterest=rofI; } };
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Constructor Ordering
contd…
int main( ) { SavingAccount S1(204,10000.0,8.75f); S1.display( ); return 0; }
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Multiple Inheritance class Membership{ protected: char typeOfMembership; public: Membership( ) {} Membership(char type) { typeOfMembership=type; } void display() { cout<<"\nThe Membership is of
class SavingAccount { static float minimumBalance; float rateOfInterest; public: SavingAccount( ) {} SavingAccount(float rofI) { rateOfInterest=rofI;
} void display( ) { cout<<"\nThe rate of Interest applied is:"<
Multiple Inheritance • • • • • • • •
Contd…
class LoanAccount: public Membership, public SavingAccount { }; int main( ) { LoanAccount B1; B1.display( ); error! return 0; }
//Ambiguity
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Hybrid Inheritance class BankAccount{ protected: int accNo; double balance; public: BankAccount( ) { accNo=0; balance=0; } BankAccount(int AccNo,double bal) { accNo=AccNo; balance=bal; } void display( ) { cout<<"Account Number:"<
Polymorphism Example int main( ) { BankAccount B1(203,10000.0); BankAccount *Baseptr=&B1; Baseptr- rel="nofollow">display( ); SavingAccount S1(204,3000.0,9.0f); Baseptr=&S1; Baseptr->display( );//calls SavingAccount.display() if display() is made virtual in base class, else calls BankAccount.display( ); CurrentAccount C1(5000.0); Baseptr=&C1; Baseptr->display( ); //calls CurrentAccount.display( ) if display( ) is made virtual in base class, else calls BankAccount.display( ); } Pragati Software Pvt. Ltd., 312, Lok Center, Marol-Maroshi Road, Marol, Andheri (East), Mumbai 400 059. www.pragatisoftware.com
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Abstract classes • No actual objects are created from it. • A class in C++ is abstract if it contains at least one pure virtual function • A virtual function equated to zero is called a pure virtual function
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Abstract classes Example class BankAccount{ protected: int accNo; double balance; public: BankAccount( ){ } BankAccount(int AccNo,double bal) { accNo=AccNo; balance=bal; } /*For making this function a pure virtual function it has to equated to zero*/ virtual void display( )=0; }; Pragati Software Pvt. Ltd., 312, Lok Center, Marol-Maroshi Road, Marol, Andheri (East), Mumbai 400 059. www.pragatisoftware.com
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Virtual Destructors class BankAccount { protected: int accNo; double balance; public: BankAccount( ){ } BankAccount(int AccNo,double bal) { accNo=AccNo; balance=bal; } /*For polymorphism this function has to declared as virtual*/ virtual void display( ){ cout<<"Account Number:"<
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Virtual Destructors class SavingAccount: public BankAccount { float minimumBalance; float rateOfInterest; public: SavingAccount ( int AccNo, double bal, float rofI) : BankAccount( AccNo, bal) { rateOfInterest = rofI; } void display( ) { BankAccount:: display( ); cout <<"\n The rate of Interest applied is:"<< rateOfInterest; } ~SavingAccount ( ){ cout<<"\nInvoking Saving account destructor..."; } }; int main( ){
BankAccount * Baseptr=new SavingAccount ( 204, 3000.0, 9.0f); delete Baseptr; } Pragati Software Pvt. Ltd., 312, Lok Center, Marol-Maroshi Road, Marol, Andheri (East), Mumbai 400 059. www.pragatisoftware.com
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Module 10: Streams • Overview
Stream class hierarchy cin.get ( )/ cin.getline( ) methods cin.ignore( ) method Manipulators
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Stream Classes A stream is a general name given to a flow of data in an input/output situation. Streams are called iostreams in C++ Advantages: No formatting characters in streams. Overloading of existing operators and functions possible
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Stream class hierarchy ios ostream
istream iostream ifstream
ofstream fstream
istream_ withassign
iostream_ withassign
ostream_ withassign
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Reading strings • Syntax
cin.get(signed char *s,int n,char_delim='\n');
cin.getline(signed char *s,int n,char_delim='\n')
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The get function 1. #include 2. using namespace std; 3. #define MAX 9 4. int main( ) 5. { 6. char str0[MAX]; 7. cout<<"Enter a string: "; 8. cin.get(str0,MAX); 9. cout<<str0<<"\n"; 10. }
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The getline function 1. 2. 3. 4. 5. 6. 7. 8. 9.
#include #define MAX 20 int main( ) { char str1[MAX]; cout<<"Enter a string: "; cin.getline(str1,MAX,'.'); cout<<str1<<"\n"; }
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Limitations of the get and getline functions 1. int 2. { 3. 4. 5. 6. 7. 8. 9. 10. 11.}
main( ) char str[30]; int code; cout<<"Enter the code of the Employee "; cin>>code; cout<<"Enter the name of the Employee "; cin.getline(str,30); cout<<str<<" has code:"<
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cin.ignore( ) • Extract and discard characters • Eg : cin.ignore(4,'\n'); cin.ignore(1); Syntax: istream& ignore ( streamsize n = 1, int delim = EOF );
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Using cin.ignore( ) 1. int 2. { 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. }
main( ) char str[30]; int code; cout<<"Enter the code of the Employee "; cin>>code; cin.ignore(4,'\n'); cout<<"Enter the name of the Employee "; cin.getline(str,30); cout<<str<<" has code:"<
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Manipulators •Special functions used to alter format parameters Manipulator
Parameter
endl
function ‘\n’
setprecision
Number of decimal digits to be displayed
precision
setfill
Fill character
fill
setw
Variable width
width
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Module 11: File I/O • Overview Opening/ Closing a file reading /writing to a file char-by-char reading /writing an object to a file
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File i/o • File stream classes declared in fstream in the namespace std ifstream Used for file input operations Derived class of istream ofstream Used for file output operations Derived class of ostream
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Opening/Closing a file • Two ways to open a file: using open function using the constructor • To close a file using close function
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Reading/Writing to File char-by-char • • • • •
#include #include using namespace std; int main( ) { char str[ ]= "Time flies over us, but leaves its shadows behind\n"; • ofstream for_write (“ char_by_char.txt"); • cout<<"\nWriting into the file character by character..."; • for ( unsigned i=0;i< strlen(str) ;i++) • for_write.put(str[i]); • for_write.close( ); • ifstream for_read("char_by_char.txt"); • char ch; • cout<<"\nReading from the file character by character and displaying ...\n"; • while(!for_read.eof( )){ • for_read.get(ch); • cout<
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Reading/Writing an object to a File #include #include using namespace std; class Person{ char name[40]; int age; public: void getData( ){ cout<<"\nEnter name:";cin>>name; cout<<"Enter age:";cin>>age; } void displayData( ){ cout<
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Reading/Writing an object to a File int main( ) { Person P1,P2; cout<<"\nEnter the data.\n"; P1.getData( ); ofstream data("Person_data.DAT"); cout<<"\nNow writing into the file..."<<endl; data.write((char *)&P1,sizeof(Person)); data.close(); ifstream data1("Person_data.DAT"); cout<<"Now reading from the file..."<<endl; data1.read((char *)&P2,sizeof(Person)); cout<<"\nData read is..."<<endl; P2.displayData(); cout<<endl; }
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Module 12: Exception Handling • Overview
Simple Exception Handling Catch-All Handler Re-throwing an exception Catching class type exceptions Handling derived class exceptions Unwinding the stack Throwing exceptions from constructors Using set_terminate ( ) function
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Exception handling • Runtime Errors are called exceptions • C++ exception handling has three keywords: try catch throw
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Syntax of a try…catch try { …………. throw exception; …………. } catch(type1 arg) { //catch block } catch(type2 arg) { //catch block } catch(type3 arg) { //catch block } Pragati Software Pvt. Ltd., 312, Lok Center, Marol-Maroshi Road, Marol, Andheri (East), Mumbai 400 059. www.pragatisoftware.com
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Simple Exception Handling • •
#include using namespace std;
• • • • •
int main( ) { try{
• • • • •
cout<<"U R IN TRY BLOCK !!"<<endl; throw 10; //throw exception of type
integer. } catch(int){ //catch handler for integer. cout<<"U R IN CATCH BLOCK !!"<<endl; } }
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Catch-All Handler int main( ) { try{ int y; cout<<"\n\nIn try block..."; cout<<"Enter the value of y:"; cin>>y; if(y= =100) throw y; //throw an excepiton of type int else cout<<"The value entered is:"<
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Re-throwing an exception void func1( ) { try{ throw "SOMETHING went wrong !!!"; } catch ( const char *s){ cout<<"Inside internal handler !!"<<endl; cout<<"\n Rethrowing the exception to the calling function..."; throw; } }
int main( ) { try{ func1( ); } catch(const char *s){ cout<<"\nBack in function main !!"<<endl; cout<<s<<endl; } }
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Catching class type exceptions int main( ) { int num; try{ cout<<"Enter a number \n"; cin>>num; if(num<0) throw MyException("Not a positive number !!",num); else cout<<"The number is a positive number:"<
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Handling derived class exceptions class A{ }; class B{ }; //class C inherits from B and A class C: public B, public A{ }; C c; B b; A a;
int main( ) { try{ throw c;
} catch (C d) { cout <<"\n Catch of derived \n \n"; } catch ( B &a){ cout<<"\n Catch of base b \n"; } catch ( A &){ cout<<"\n Catch of base a\n"; } } Pragati Software Pvt. Ltd., 312, Lok Center, Marol-Maroshi Road, Marol, Andheri (East), Mumbai 400 059. www.pragatisoftware.com
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Unwinding the stack class Employee{ int acc_no; char name[10]; public: Employee(int x,char *str){ acc_no=x;
int main( ) { try{ Employee emp(1,"Sunil"); cout<<"\nException generated..."; throw 1; } catch ( int){ strcpy(name,str); cout<<"\n In Exception } Handler"<< endl; ~Employee( ){ } cout<<"\nIn the } destructor"; } };
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Throwing exceptions from constructors class Engineer{ public: Engineer( ){ cout<<"Inside } ~Engineer( ){ cout<<"Inside } }; class Manager{ public: Manager( ){ cout<<"Inside } ~Manager( ){ cout<<"Inside } };
Engineer constructor !!"<<endl; Engineer destructor !!"<<endl;
Manager constructor !!"<<endl; Manager destructor !!"<<endl;
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Throwing exceptions from constructors Contd… class EngineerManager : public Manager{ public: EngineerManager ( ){ cout<<"Inside EngineerManager constructor !! "<<endl; Engineer e; throw -1; } ~EngineerManager ( ){ cout<<"Inside EngineerManager destructor !! "<<endl; } }; int main( ){ try{ EngineerManager EM; } catch(int){ cout<<"CAUGHT AN ERROR"<<endl; } Pragati}Software Pvt. Ltd., 312, Lok Center, Marol-Maroshi Road, Marol, Andheri (East), Mumbai 400 059. www.pragatisoftware.com
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Using set_terminate ( ) function void Big_crunch ( ){ cout<<"UNEXPECTED ERROR IN APPLICATION !! "<<endl<< “Exiting to os"<<endl; exit(-1); } int main( ){ set_terminate ( Big_crunch); try{ throw 1; //throw exception of type int. } catch ( char ){ cout<<"CAUGHT IN BLOCK"; } return 0; } Pragati Software Pvt. Ltd., 312, Lok Center, Marol-Maroshi Road, Marol, Andheri (East), Mumbai 400 059. www.pragatisoftware.com
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Module 13: RTTI and Casting Operators • Overview
typeinfo class and using the typeid object dynamic_cast const_cast static_cast reinterpret_cast
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RTTI • RTTI: Run Time Type Identification. • This allows to identify object-type during program execution. • Syntax: typeid(object); • Uses #include returns a reference to an object of type type_info. • type_info is a class that describes the type of object and defines the following public members: • typeid
bool operator ==(const type_info &ob); bool operator !=(const type_info &ob); bool before(const type_info &ob); const char *name( );
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typeinfo class #include #include using namespace std; class ClsBase{ virtual void func( ){ cout<<"In base class"; } }; class class2{ }; class ClsDerv:public ClsBase{ void func( ){ cout<<"HI"; } }; Pragati Software Pvt. Ltd., 312, Lok Center, Marol-Maroshi Road, Marol, Andheri (East), Mumbai 400 059. www.pragatisoftware.com
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Using typeid int main( ){ int i,j; float f; char * chp; ClsBase obj1,*ptr=0; class2 obj2; ClsDerv d1,*dptr=0; cout<<"Data type of int i is:"<
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Using typeid if(typeid(i)==typeid(j)) cout<<"\nBOTH i and j are integers and of the same type"<<endl; if(typeid(i)==typeid(f)) cout<<"BOTH i and f are of the same type"<<endl; else cout<<"i and f are not the same type"<<endl; cout<<endl; if(typeid(obj1)==typeid(obj2)) cout<<"BOTH obj1 and obj2 are of the same type"<<endl; else cout<<"obj1 and obj2 are not the same type"<<endl; cout<<endl; cout<<"\nThe number preceding the name indicates the number of characters in the class name "<<endl; cout<<"The type of obj1 is:"<
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Using typeid cout<<"The type of obj1 is:"<
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Casting Operators • Explicit Casting operators • Syntax: cast_name (expression); • • • •
dynamic_cast static_cast const_cast reinterpret_cast
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dynamic_cast class Base { public: virtual void display( ) { cout<<"In base"; } }; class Derived:public Base { public: void display( ) { cout<<"In Derived"; } };
void main( ){ Base *bp; Derived *dp, d; bp = &d; if(!bp) cout<<"Casting failed"; dp = dynamic_cast(bp); if(!dp) cout<<"Casting failed"; else cout<<"Dynamic casting successful !!”; }
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const_cast • • • • • •
int square ( const int *val){ int *ptr; ptr = const_cast ( val); *ptr = *val * *val; return *ptr; }
• • • • • •
int main( ){ int num=5; cout<<"Number:"<
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static_cast • • • • • • • • • • •
int main( ) { int cnt; double tmp; for(cnt=1; cnt<=10; cnt++) { tmp = static_cast<double> (cnt)/2; cout<
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reinterpret_cast • • • • • • • •
int main( ){ int num=100, add; int *ptr = # cout<<"num address:"<<(int)# add = reinterpret_cast (ptr); cout<<"add value:"<
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Module 14: Templates • Overview Template Function with one argument Template Function with two arguments Class Templates
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Templates • Syntax for Function Template: template ret-type func-name ( parameter list) { // body of function }
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Template Function with one argument • • • • • • • • • •
template T abs(T a) { return (a<0)?-a:a; } int main( ) { int num1=-34; num1=abs(num1); cout<<"Absolute value of the integer passed as an argument: "<
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Template Function with two arguments • • • • • • • • • • • • • • • • •
template void display(TY a,TB b){ cout<
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Class Template • #include • #include<string> • using namespace std;
1. void pop( ){ 2. if(top>=0) { 3. cout<<"Popping..."<<endl; • template 4. top--; • class Stack{ 5. } • Any arr[4]; 6. else • int top; 7. cout<<"Stack is • public: Empty!!"; • Stack( ) { 8. } • top= -1; 9. void display( ){ • } 10. if(top<0) { • void push( Any x) 11. cout<<"Stack is • { Empty\n"; • if(top<4) 12. return; • arr[ ++ top]=x; 13. } • else 14. cout<<"Stack elements • cout<<"Stack are:"<<endl; Overflow!!"; 15. for(int i=top;i>=0;i--) Pragati Pvt. Ltd., 312, Lok Center, Marol-Maroshi Road, Marol, Andheri (East), Mumbai 400 059. www.pragatisoftware.com • Software} 16.
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Class Template
• cout<<"Stack of strings....."<<endl; • int main( ) • Stack<string> S2; • { • S2.push("Hi"); • cout<<"Stack of • S2.push("Hello"); Integers....."<<endl; • S2.push("What's"); • Stack S1; • S2.display( ); • S1.push(3); • S2.pop( ); • S1.push(33); • S2.display( ); • S1.push(111); • cout<<"Pushing element ........."<< • S1.display( ); • S2.push("UP!!"); • S1.pop( ); • S2.display( ); • S1.display( ); • cout<<"Popping 3 elements : "<<e • cout<<"Pushing • element"<<endl ; S2.pop( ); • • S1.push(23); S2.pop( ); • • S1.display( ); S2.pop( ); • • cout<<"Popping 3 S2.display( ); elements"<<endl; • • S1.pop( ); • return 0; • S1.pop( ); • } Pragati Pvt. Ltd., 312, Lok 252 • SoftwareS1.pop( );Center, Marol-Maroshi Road, Marol, Andheri (East), Mumbai 400 059. www.pragatisoftware.com
Defining Member functions of Class Templates • template • • class Stack{ • Any arr[4]; • int top; • public: • Stack( ); • void pop( ); • void push( Any); • void display( ); • };
• • • • •
cout<<"Stack Overflow!!"; } template void Stack::pop( ){ if(top>=0){
cout<<"Popping..."<<endl; • top--; • } • else • cout<<"Stack is • template Empty!!"; • Stack::Stack( ) • } { • template • top=-1; • void Stack::display( • } ){ • if(top<0){ • template • cout<<"Stack is • void Empty"<<endl; Stack::push( • return; Any x){ • } • if(top<4) Pragati Software Pvt. Ltd., 312, Lok Center, Marol-Maroshi Road, Marol, Andheri Mumbai 400 059. www.pragatisoftware.com • (East), cout<<"Stack elements
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1 195.01.03
Table of Contents Module 1: Getting Started Module 2: Arrays Module 3: Functions Module 4: Pointers and References Module 5: Classes and Objects Module 6: Friend Keyword Module 7: Operator Overloading Module 8: Inheritance Module 9: Polymorphism and Abstract classes Module 10: Streams Module 11: File I/O Module 12: Exception Handling Module 13: RTTI and Casting Operators Module 14: Templates
5 63 77 104 132 168 173 184 199 208 218 224 236 247
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C++ Programming Developed by : Bjarne Stroustrup Where : Bell Telephone Laboratories When : 1979 Influenced by: C Influenced : C#, Java
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Features of C++ • • • • •
Object-oriented programming Portability Modular programming C Compatibility Speed
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Module 1: Getting Started • Overview
First C++ program Standard O/P and I/P in C++ Data types and Modifiers Variables and Constants Operators Loops and Conditions Type Conversions
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The first C++ program • • •
/* First.cpp */ #include
• • • • •
int main( ) { cout<<"Hello! This is my first C++ program\n"; return 0; }
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The first C++ program
contd…
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Standard Output Consider the statements cout<<“value of var1is :”; int var1=14; cout<< var1; cout<<“The addition of ”<
Syntax: cout<<“string”; cout<
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Standard Input Consider the statements cin rel="nofollow">> var1; cin>>x>>y;
Syntax:
cin>>variable1; cin>>cascade1>>cascade2;
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Data types • Fundamental data types in C++ Type Integer Character Floating Point Double precision floating point Boolean
Keyword int char float double bool
• Modifiers signed , unsigned short, long void Pragati Software Pvt. Ltd., 312, Lok Center, Marol-Maroshi Road, Marol, Andheri (East), Mumbai 400 059. www.pragatisoftware.com
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Data Type Modifiers TYPE
SIZE (Bytes) for TC++
SIZE (Bytes) for Windows/ Unix
char or signed char
1
1
unsigned char
1
1
int or signed int
2
4
unsigned int
2
4
short int or signed short int unsigned short int
2
2
2
2
long int or signed long int unsigned long int
4
4
4
4
float
4
4
double
8
8
10
10
long double
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Variables & Constants • Variable – a physical entity which can be changed E.g. height, weight, temperature etc.
• Constant – a physical entity which never changes E.g. pi value, number of days in a week etc.
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Variables • • •
All variables must be declared before being used. In C++ variables can be declared anywhere in the code. A variable may be initialized with a value while declaring it, by using the ‘=’operator
Naming rules: 6. The first character must be a letter or an underscore 7. Subsequent characters must be either letters, digits, or underscores. 8. Keywords , white spaces, punctuation marks or symbols not allowed
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Declaring variables Example: int x, y, z; char name=‘G’;
Syntax for declaration datatype v1, v2, v3, …………vn; datatype u1=value1,u2,u3=value2…;
where v1, v2, v3 are variable names.
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The ‘sizeof’ operator Consider the statements cout<<sizeof (int); cout<<sizeof x;
Syntax: sizeof (datatype); sizeof variableName;
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The Constants Types: integer, character, string, float. Integer Constants Integers are whole numbers. Default is decimal. Octal numbers preceded by a ‘ 0 ’. Hexadecimal numbers are preceded by a ‘ 0x ’. Long integers specified using ‘ l ’ after an integer
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The Constants
contd…
Character Constants: A single character is enclosed in single quotes. Some Escape sequence character constants: '\n' '\t' '\r' '\b' '\a' '\\' '\’'
new line horizontal tab carriage return backspace alert backslash apostrophe
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The Constants
contd…
String Constants : Sequence of characters enclosed in double quotes. A null terminated character automatically placed at the end of each string .
Float Constants: Used to represent floating numbers Consist of an integer part, a decimal point and a fraction part. Scientific notation can also be used.
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The Constants
contd…
1. /*Program to demonstrate use of constants*/ 2. int main ( ) 3. { 4. int num1=10; /*10 is an integer constant */ 5. double num2=28.5; /*28.5 is a floating point constant */ 6. char c = 'W'; /* ‘W’ is a character constant */ 7. cout<<"This is a constant string."; 8. cout<<"\nThe value of num1="<< num1; 9. cout<<"\nThe value of num2="<< num2; 10. cout<<"\nThe character "<
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Defining Symbolic Constants Consider the statement: # define PI 3.14159
Syntax: # define symbolic_name value
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The Symbolic Constants 1. #define TEN 10 2. #define RNUM 28.5 3. #define CHARACTER 'C' 4. #define STRING "This is a constant string." 5. int main ( ){ 6. int num1 = TEN; 7. double num2 = RNUM; 8. char c = CHARACTER; 9. cout<<STRING; 10. cout<<"\nThe value of num1="<
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The Constant Variables • Variables of type (qualifiers) const cannot be changed by the program. • However, it can be given an initial value. • Used as a READ ONLY variable. Syntax: const datatype variable_name=value;
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The Operators Types: Arithmetic Assignment Relational Logical Bitwise
: + - ++ -- + - * / % : = , += -= *= /= %= : > < >= <= == != : && || ! : & | ^ << >> ~
Also classified into : Unary
: &(addr) *(indirect) +(sign) –(sign) ~(complement) !(NOT) ++(incre) --(decre) Binary : All other operators listed above Ternary : Conditional operator(? :)
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Increment and Decrement Operators An increment operator (++) adds 1 to its operand. A decrement operator (--) subtracts 1 from its operand. i ++; ++i; i --; --i;
/* i = i + 1 (post fixed) */ /* i = i + 1 (prefixed) */ /* i = i - 1 (post fixed) */ /* i = i - 1 (prefixed) */
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Special Assignment Operators The expression i = i + 5;
can also be written as i += 5;
/* Add 5 to i */
Similarly, i -= 5; i *= 5; i /= 5;
/* Subtract 5 from i */ /* Multiply i with 5 */ /* Divide i by 5 */
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Fahrenheit to Celsius conversion 1. #include
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Logical operators 1. int main ( ){ 2. float f1, f2; 3. cout << "Enter a floating point number (f1)" << endl; 4. cin >> f1; 5. cout << "Enter another floating point number (f2)" << endl; 6. cin >> f2; 7. cout << "f1 > f2 is " << (f1 > f2) << endl; 8. cout << "f1 < f2 is " << (f1 < f2) << endl; 9. cout << "f1 == f2 is " << (f1 == f2) << endl; 10. cout << "f1 != f2 is " << (f1 != f2) << endl; 11. cout << "f1 >= f2 is " << (f1 >= f2) << endl; 12. cout << "f1 <= f2 is " << (f1 <= f2) << endl; 13. cout << "f1 && f2 is " << (f1 && f2) << endl; 14. cout << "f1 || f2 is " << (f1 || f2) << endl; Pragati Software Pvt. 15. }Ltd., 312, Lok Center, Marol-Maroshi Road, Marol, Andheri (East), Mumbai 400 059. www.pragatisoftware.com
27
Loops and Conditions • Overview Selection if statement switch statement
Iteration while do while for
Control flow transfer statements break continue goto
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Selection Statements • Selection The if statement The switch statement
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The if statement Start
Statement1
True
If condition
Statement
End Pragati Software Pvt. Ltd., 312, Lok Center, Marol-Maroshi Road, Marol, Andheri (East), Mumbai 400 059. www.pragatisoftware.com
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The if…else statement Start
Statement1
True
If condition
False Statement2
Statement3
End Pragati Software Pvt. Ltd., 312, Lok Center, Marol-Maroshi Road, Marol, Andheri (East), Mumbai 400 059. www.pragatisoftware.com
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if construct if (i==3) cout<<“Hattrick!!”; if ( year_of_service>3) bonus=2500; if ((percentage>=40) && (percentage<50)) cout<<“Third division”;
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if construct -- different forms if(condition) Statement
if(condition) { Statements }
if(condition) Statement else Statement
if(condition) { Statements } else { Statements }
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if else
contd…
if(condition) { if(condition) Statement else Statement } else { if(condition) Statement else Statement }
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The if…else if ladder if(condition) { Statement } else if(condition) { Statement } else if(condition) { Statement } else { Statement }
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Conditional Operator Syntax: exp1 ? exp2 : exp3
If exp1 evaluates to true, then exp2 is returned else exp3 is returned
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Program to find vowel 1. int main( ) 2. { 3. char ch; 4. cout<<"\nEnter any character : "; cin>>ch; 5. if(ch=='a') cout<<"\n"<
37
Using the || operator 1. int main( ) 2. { 3. char ch; 4. cout<<"\nEnter any character : "; 5. cin>>ch; 6. if(ch=='a' ||ch=='e' || ch=='i'|| ch=='o' || ch=='u') 7. cout<
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The nested if-else 1. 2. 3. 4.
int main ( ) { int a=4,b=4; char ch; cout<<"Enter which operation u wish to perform"; cin>>ch; 5. if (ch == '+') a += b; 6. else if (ch == '-') a -= b; 7. else if (ch == '*') a *= b; 8. else if (ch == '/') a/=b; 9. else{ 10. cout<<"Error"; 11. return 1; 12. } 13. cout<<"Result is :"<
39
The switch statement Syntax: switch ( integer expression) { case constant1: statements; case constant2: statements; case constant3: statements; default: statements; }
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Using the switch-case The example for nested-if can be modified using switch- case as follows: switch (ch){ case '+' : a += b; break; case '-' : a -= b; break; case '*' : a *= b; break; case '/' : a /= b; break; default : cout<<"error"; }
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Program to find vowel using switch-case • • • • • • • • • • • • • • • •
int main( ){ char ch; cout<<"\nEnter any character : "; cin rel="nofollow">>ch; switch(ch) { case 'a': case 'e': case 'i': case 'o': case 'u': cout<
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Iteration • The while loop • The do-while loop • The for loop
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The while loop Start
while condition
false Exit loop
true statements
End
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The while loop Consider the statements while(i<=10) while(i>=1) while(i<=10 && j<=15)
Syntax: while (expression) statement;
while (expression) { statement1; statement2; }
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Using while • • • • • •
#include
• • • • • • •
while(i<=10) { cout<<“\nValue of i is :”<
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Using while
Contd…
1. #include
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The do - while loop Start
statements
true
while condition
false
Exit loop End
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The do - while loop
Contd…
Syntax: do
do{ statement; while (expression);
statement1; statement2; } while (expression);
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Using do-while 1. #include
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The for loop Start
for condition
false Exit loop
true statements
End
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The for loop
Contd…
Consider the statements for(i=0;i<5;i++) for(i=10;i>=0;i--)
Syntax: for (exp1;exp2;exp3) { statement1; statement2; }
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Using for • • • • • • • • •
#include
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Nesting of for loop 1. #include
54
Control Flow Transfer Statements
break; continue; goto labelName;
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Using ‘break’ • • • • • • • • • • • • •
#include
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Using ‘continue’ • • • • • • • • • • • • •
#include
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Using ‘goto’ • • • • • • • • • • • • •
#include
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Type Conversion Implicit Conversion: In C+ +, the following program code is valid, and will result in proper evaluation: int i, j; char k; ... i = j + k;
The type of the variable k is converted from char to int, and then used in the expression.
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Implicit Conversion 1. 2. 3. 4. 5. 6. 7. 8.
#include
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Explicit Conversion Consider the following program code: long i; int j, k; i = j + k;
Explicit casting : i = (long) j + k;
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Explicit Conversion 1. 2. 3. 4. 5. 6. 7. 8.
contd…
#include
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62
Module 2: Arrays • Overview Definition Array of integers and characters Initialization of arrays String manipulation functions Multidimensional Arrays
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63
Arrays • Collection of variables of
Similar data type Referred by a common name Stored in consecutive memory locations Array values can be accessed via its subscript
e.g. int marks[5];
Syntax: datatype ArrayVariableName[ number of elements] ;
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Array example • • • • • • • • • • • • • • • • •
#include
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Arrays of Characters 1. #include
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The ‘cin’ and strings 1. #include
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Initialisation of Arrays int score[11] = {89,125,56,45}; Index number Or subscript
Values
0
1
2 3
4
5
score 89 125 56 45 0 0 100
102
104
106
108 110
6 0
7 0
112 114
8
9 10
0 116
0 118
0 120
Memory locations ArrayName Pragati Software Pvt. Ltd., 312, Lok Center, Marol-Maroshi Road, Marol, Andheri (East), Mumbai 400 059. www.pragatisoftware.com
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Char Arrays or Strings
char name[10]=“Rosy”;
0
1
2
3
4
R o
s
y
\0
100
101 102
5
6
7
8
103 104 105 106 107 108
9
109
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69
Some string manipulation functions strlen ( ) strcpy ( ) strcat ( ) strcmp ( )
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Some string manipulation functions Syntax: int strlen (const char *source); char *strcpy(char *destination, const char *source); char *strcat(char *Destination, char *Source); int strcmp (const char *string1, const char *string2);
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Using string functions • • • • • • • • • • • • • • •
#include<string.h> int main( ){ char str1[20]="C ",str2[20]="Programming in ",str3[30]=""; cout<<"Length of str1 is "<<strlen(str1); strcat(str2,str1); //append str1 at the end of str2 cout<<"\nstr2 is "<<str2; strcat(str3,str2); strcat(str3,"language"); cout<<"\nlength of "<<str3<<" is "<<strlen(str3); if( strcmp("apple","Apple")>0) cout<<"\nfirst string is greater"; else if ( strcmp("apple","Apple")<0) cout<<"\nsecond string is greater"; else cout<<"\nboth strings are equal“;
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72
Multi-Dimensional Arrays Consider the statement int student[5][2];
Syntax: datatype variableName [index1]….[indexn] The 3rd element from the 1st row can be accessed by, student[2][1]
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73
A double dimensional array 1. int main( ){ 2. int total=0,i,j,col=1,row=2; 3. int score[3][11]= { 4. {95,25,56,45,75}, 5. {14,22,88,37,95,12}, 6. {84,25,16,23,6,89,12,34} 7. }; 8. for(i=0;i<3;i++) { 9. cout<<"Test: "<
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74
Strings char days[7][10]={ “Monday”, “Tuesday”, “Wednesday”, “Thursday”, “Friday”, “Saturday”, “Sunday” };
Index
100
0
M o
n
d
a
y
\0
1
T u
e
s
d
a
y
\0
2
W e
d
n
e
s
d
a
y
3
T h
u
r
s
d
a
y
\0
4
F
r
i
d
a
y
\0
5
S
a
t
u
r
d
a
6
S
u
n
d
a
y
\0
110
\0
120
Memory Locations
130 140
y
\0
150 160
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75
Printing the array of strings 1. int main( ){ 2. char month[10]="May"; 3. char days[7][10]={ 4. "Monday", 5. "Tuesday", 6. "Wednesday", 7. "Thursday", 8. "Friday", 9. "Saturday", 10. "Sunday" 11. }; 12. cout<<"\nMonth is : "<<month; 13. for(int i=0;i<7;i++) 14. cout<<" \n Day is :"<
76
Module 3: Functions • Overview Definition User defined functions Storage Classes Recursion Default Arguments Function Overloading Inline functions Scope Resolution operator
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Functions • Set of statements written in a separate body • To perform a distinguishable task • Functions are classified into 1) Library or built-in functions 2) User defined functions
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Library functions • Library or built-in functions eg. strcpy( ), strcat( )
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The User defined functions • Syntax: return_type function_name (argument list) argument declarations { declarations; executable statements; }
Eg: int show_age(int age ); int cal_age(char );
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Creating a user defined function Function header or function prototype Return type
Function name
int isEven value)
Formal Parameter list (int
{ if(value % 2 == 0) return 1; else return 0; }
Function body
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Function types • Without argument & without return value void clrscr(void);
• With argument but no return value void gotoxy(int x, int y);
• With argument & with return value int abs(int num);
• Without argument but with return value int getchar( );
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82
Program to compute power of an integer 1. int power (int,int); 2. int main ( ){ 3. int i; 4. for (i = 0; i < 10; i++) 5. cout<<<"\t"<<power(2, i)<<"\t"<<power (3, i)<<endl; 6. return 0; 7. } 8. int power(int base,int n){ 9. int i, p; 10. p = 1; 11. for (i = 1; i <= n; i++) 12. p *= base; 13. return p; 14. } Pragati Software Pvt. Ltd., 312, Lok Center, Marol-Maroshi Road, Marol, Andheri (East), Mumbai 400 059. www.pragatisoftware.com
83
Classification of variables Based on the position of declaration in the program Storage class. Based on position Local Global
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84
Scope of variables Local variables
Global variables
Declared within any function body
Declared outside of any function body
Available only within declaring function
Available to the entire program, hence can be shared by other functions
Are lost as soon as the declaring function body terminates • void fun( ) • { • int i=10; /*local to fun */ • } • void foo( ) • { • int i=10; /*local to foo */ • }
Are lost as soon as the declaring application or program terminates • int k=10; /* global to prg */ • void fun( ) • { • int i=10; k=35; • } • void foo( ) • { • int i=10; cout<
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Storage Classes The storage class gives the following information about the variable: Where it is stored Its initial value Scope of variable Lifetime of the variable i.e. how long it exists
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86
Automatic Keyword : auto Locations : Memory Initial Value: Garbage Scope : Only in the function or block in which it is declared Lifetime : Only in the function or block in which it is declared Example : auto int num1;
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Register Keyword : register Locations : Register Initial Value: Garbage Scope : Only in the function or block in which it is declared Lifetime : Only in the function or block in which it is declared Example : register int num1;
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Static Keyword : static Locations : Memory Initial Value: 0 Scope : Only in the function or block in which it is declared Lifetime : From the point of declaration to the end of the program Example : static int num1;
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Difference between auto and static variables 1. #include
main( ) cout<<"Invoking function inc( )...."; inc( ); inc( ); inc( ); cout<<"Invoking function inc_i( )...."; inc_i( ); inc_i( ); inc_i( ); return 0;
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Difference between auto and static variable • • • • •
void inc( ){ int i=0; /* auto variable */ i++; cout<<"\nValue of i:"<
• • • • •
void inc_i( ){ static int i; /* static variable */ i++; cout<<"\nValue of i:"<
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Extern Keyword : extern Locations : Memory Initial Value: last value attained in a previous file Scope : global Lifetime : global Example : extern int num1;
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Example of extern 1. /* Source file F04GlobalVar.cpp */ 2. int n = 3; 3. void alter ( ); 4. int main ( ) 5. { 6. cout<< n; 7. alter( ); 8. cout<< n; 9. return 0; 10. }
1. /* Source file F04ExternExample.cpp */ • • • • •
extern int n; void alter ( ) { n = 10; }
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Making Data and Functions Private static int array [MAX]; int array2 [20]; int main ( ) { ... } static int privatefun ( ) { ... } double publicfun ( ) { ... } Pragati Software Pvt. Ltd., 312, Lok Center, Marol-Maroshi Road, Marol, Andheri (East), Mumbai 400 059. www.pragatisoftware.com
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Recursion • Function makes a call to itself • Repeatedly invokes itself until a condition is met • Hence must have a return statement to exit
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95
Finding factorial using recursion 1. #include
96
Default Arguments Eg: cin.ignore(1); & cin.ignore(4,’\n’); square(6); & square(6, 10);
Syntax: return_type func_name( arg1, arg2, …., argn = value){ //executable statements; }
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Using default arguments • • • • • •
int add(int,int=0); int main( ){ cout<
• • •
int add(int x,int y){ return x+y; }
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Function overloading void void void void
max (int, int); max (float, float); max (char , char); max (int, int, int);
Function calls will be: max(87, 65); max( 35.5f, 76.6f); max( ‘J’, ‘L’); max(45, 90, 23);
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Using function overloading 1. void add(int x,int y){ cout<<x+y<<endl; 2. } 3. void add(float x,float y) { cout<<x+y<<endl; 4. } 5. void add(int x,float y){ cout<<x+y<<endl; 6. } 7. void add(float x,int y){ cout<<x+y<<endl; 8. } 9. int main( ){ 10. add(10,10); 11. add(30,20.15f); 12. add(16.57f,4); 13. add(3.25f,6.44f); 14. return 0; 15. }
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Ambiguity 1. void add(int x,int y=15){ 2. cout<<x+y<<endl; 3. } 4. void add(int x,int y){ 5. cout<<x+y<<endl; 6. } 7. int main( ){ 8. add(13); 9. add(10,10); 10. return 0; 11. }
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101
Inline functions • To avoid the run-time overhead when using functions Eg: inline int min (int v1,int v2){ return (v1 < v2 ? v1 : v2 ); }
• Syntax inline return_type function_name (argument_list){ //executable statements; }
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Scope Resolution operator (::) 1. • • • • • • •
int count = 0; int main(void) { int count = 0; ::count = 1; // set global count to 1 count = 2; // set local count to 2 return 0; }
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Module 4: Pointers and References • Overview Definition and declaration Pointer to an array Pointer arithmetic Pointers as function arguments Array of pointers Pointer to pointer Command line arguments Function pointers References in C++
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104
Pointer • Variable which holds a only memory address pointer variable = 65524
Name
Num
Value
189
Memory address
65524
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Pointer declaration
datatype *pointerVariableName; pointer declaration Type of that variable whose address will be stored by the pointer
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Pointer declaration & initialization Syntax for Initialization : pointerVariableName = & variable; Address Of
Declaration-cum-Initialization datatype *pointerVariableName = &variable;
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Pointer example 1. int main( ) { 2. int x=10,y=20,z=30; 3. int *ptr = &x; 5.
cout<<"Value of x:"<<x<<endl; 6. cout <<"Value at *ptr:"<<*ptr<<endl; 7. cout <<"Value at &x:"<<*&x<<endl<<endl;
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cout <<"Address of x:"<<(unsigned)( &x)<<endl; 10. cout <<"Address pointed by the pointer:"<<(unsigned)ptr<<endl ;
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12. cout<<"Changing the contents at address pointed by ptr... Pragati Software Pvt. Ltd., 312, Lok Center, Marol-Maroshi Road, Marol, Andheri (East), Mumbai 400 059. www.pragatisoftware.com
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Pointer example
contd…
1. cout<<"Changing the ptr address ... "<<endl; 2. ptr=&y; 3. cout<<"Value of y:"<
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6. cout <<"Address of x:"<<(unsigned)(&y)<<endl; 7. cout <<"Address pointed by the pointer:"<<(unsigned)ptr<<endl; 8. 9. cout<<"The size of the pointer is:"<<sizeof(ptr)<<endl; 10. return 0; 11. }
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Pointer to an Array 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11.
int main ( ){ int ary[5]={10,20,30,40,50}; int *ptr, i; for(i=0;i<5;i++){ ptr=&ary[i]; cout<<*ptr<<'\t'; } cout<< endl<<"Size of pointer:"<<sizeof(ptr); cout<<endl<< "Size of array:"<<sizeof(ary)<<endl; return 0; 0 1 2 3 4 }
ary 10 20 30 40 50 100
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Pointer arithmetic • Operations allowed on pointers Pointer and integer addition Pointer and integer subtraction Pointer and pointer subtraction Pointer and pointer relational operations
• Operations NOT allowed on pointers Pointer and pointer addition All division and multiplication operations
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Pointer addition • ptr++ or ptr-- : Increments or decrements the pointer by the size in bytes depending upon the data for which pointer is declared
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Accessing array elements using pointers Hence, the previous program can also be written as: 3. int main( ){ 4. int ary[5]={10,20,30,40,50}; 5. int *ptr= ary; 6. for(;ptr<&ary[5];ptr++) 7. cout<<*ptr; 8. return 0; 9. }
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Pointers to Character Strings 1. void copy_string (char *from, char *to) 2. { 3. for ( ; *from != '\0'; ++ from, ++ to) 4. *to = *from; 5. *to = '\0'; 6. }
Or, better still: 8. void copy_string (char *from, char *to) 9. { 10. while (*from) 11. *to ++ = *from ++; 12. *to='\0'; 13. }
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Pointer subtraction 1. 2. 3. 4. 5. 6. 7.
int main( ){ int ary[5]={10,20,30,40,50}; int *ptr,*ptr1=ary; for(ptr=ary;ptr<&ary[5];ptr++){ cout<<*ptr; } cout<<“Number of elements in the array are:”<
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Example of pointer subtraction 1. 2. 3. 4. 5. 6. 7. 8.
/* Function to find the length of a string. */ int str_len (char *s) { char *p = s; while (*p != '\0') p ++; return (p - s); }
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Pointers as function arguments • Two methods to call a function with arguments Call by Value Call by reference
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Pass by value • • • • • • • •
int main( ) { void swap(int, int); int x=10, y=20; cout<<x<<‘\t’<
• • • • • •
void swap(int num1, int num2) { int temp; temp=num1; num1=num2; num2=temp; }
// 10 20 // 10 20
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Pass by address • • • • • • • • • • • • • •
int main( ) { void swap(int*, int*); int x=10, y=20; cout<<x<<‘\t’<
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Pass by value vs. Pass by address main( )
main( )
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swap(x,y); swap(int x, int y)
swap(&x,&y); swap(int *x, int *y)
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Arrays of Pointers Examples: char *argv[4];
Syntax: datatype *pointerName[arraySize];
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Array of pointers • • • • • • • • • • • •
int main ( ) { int num1 = 1, num2 = 2, num3 = 3; int i; int *iptr [3]; iptr [0] = &num1; iptr [1] = &num2; iptr [2] = &num3; for (i = 0; i < 3; i ++) cout<< *iptr [i]; return 0; }
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Array of pointers int main( ) { int ary1[3]={10,20,30}; int ary2[5]={2,4,6,8,10}; int ary3[7]={8,16,32,64,128,256,512},i; int *ptr[3]; //collection of 3 pointers in an array ptr[0]=ary1; ptr[1]=ary2; ptr[2]=ary3; for(i=0;i<3;i++) cout<<(ptr[0]+i) ; cout<< endl; for(i=0;i<5;i++) cout<<(ptr[1]+i) ; cout<< endl; for(i=0;i<7;i++) cout<<(ptr[1]+i) ; cout<< endl; return 0; } Pragati Software Pvt. Ltd., 312, Lok Center, Marol-Maroshi Road, Marol, Andheri (East), Mumbai 400 059. www.pragatisoftware.com
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Array of pointers to character strings int main ( ) { int num; cout<<“Enter month number "; cin rel="nofollow">>num; cout<<"The month name is :“<<month (num) ; return 0; } char *month (int n) { char *name[ ] = {"Illegal month", "January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December" }; return ( (n < 1 || n > 12) ? name [0] : name [n] ); }
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Pointer to pointer int main( ) { int x=10; int *ptr1=&x;
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int **ptr2 = &ptr1;
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int ***ptr3 = &ptr2; cout<<***ptr3; return 0; }
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Command Line Arguments
Syntax
main( int argc, char * argv [ ])
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Accessing command line parameters /* Program to type command line strings */ int main (int argc, char *argv [ ] ) { int i; for (i = 1; i < argc; i ++) cout<<“arg “<<<“is :“<< argv [i] ; }
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Function pointers void show1(char x, char y) { cout<<"\n Characters : “<<x<<“ & ”<
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References Eg: int i; int &x=i;
Syntax: data_type & reference_variable = variable;
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Swapping two integers with references • void swap(int &int1,int &int2){ • int temp = int2; • int2 = int1; • int1 = temp; • } • int main( ) { • int num1 = 10; • int num2 = 20; • cout<<"Before swap:\tnum1: "<
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Using References 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20.
int look_up (const int *array, int size, int value, int &occurs){ int index = -1; for (int ix = 0; ix < size; ++ix) if(array [ix] == value){ if (index == -1) index = ix; ++occurs; } return index; } int main( ){ int arry[]={10,24,10,35,62,10,24},no_elements=0; int position=look_up(arry,(sizeof arry)/(sizeof(int)),35,no_elements); if(position==-1) cout<<"Number is not in the array"<<endl; else{ cout<<"Position:"<<position<<endl; cout<<"No of occurances:"<<no_elements<<endl; } return 0; }
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Module 5:Classes and Objects • Overview
Classes and Objects this pointer Constructors Dynamic Memory Allocation Destructors static Data Members and Member Functions const Functions
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Classes • Classes are user defined data types • Syntax class tag_name { private: // --- member variables & functions protected: // --- member variables & functions public: // --- member variables & functions };
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Using class declaration • • • • • • • • • • • • •
class BankAccount { //default access is private. unsigned acc_num; double balance; void deposit(double amt){ balance+=amt; } void withdraw(double amt){ balance-=amt; } void display( ){ cout<<"Account NUMBER-"<
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Access Specifiers • private : Members are accessible within the class only. They are not inherited by the derived class. • public :
Members are accessible anywhere. They are also inherited by the derived classes.
• protected : Members are accessible in the class itself & also inherited by the derived classes
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Using Access Specifiers • class BankAccount { //default access is private. • unsigned acc_num; • double balance; • public: • void deposit(double amt){ • balance+=amt; • } • void withdraw(double amt){ • balance-=amt; • } • void display( ){ • cout<<"Account NUMBER-"<
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Using the member functions 1. int 2. { 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. }
main( ) BankAccount ba; ba.display( ); ba.deposit (5000); cout<<"Balance after depositing Rs.5000/- :"; ba.display( ); ba.withdraw(1000); cout<<"Balance after withdrawing Rs.1000/- :" ; ba.display( ); return 0;
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Scope Resolution operator & class members 1. 2. 3. 4. 5. 6. 7. 8.
#include
10. 11. 12. 13. 14.
int main ( ) { int X = 0; // hides class type X cout << X::count << endl; // use member of class X return 0; }
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Defining member functions using operator :: 1. 2. 3. 4. • • • •
class BankAccount { unsigned acc_num; double balance; public: void setdata ( unsigned , double) void deposit(double); void withdraw(double); void display( ); };
• • •
void BankAccount :: withdraw(double amt) { balance-=amt; }
• • •
void BankAccount :: deposit(double amt) { balance+=amt; }
• •
void BankAccount :: display( ) { cout<<"Account NUMBER-"<
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this pointer void BankAccount :: setdata ( unsigned acc_num, double balance) { this → acc_num = acc_num; this → balance = balance; }
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Constructors • Automatic initialization done with special member function called Constructors i.e., • Constructor is executed automatically whenever an object is created. • Constructors have, Same name as class No return type • Constructors can take arguments • Constructors can be overloaded
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Constructors • Syntax to declare a constructor class_name (argument_list); •
Syntax to define a constructor class_name::class_name(argument_list){ // body of constructor function; }
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Types of Constructors • • • •
Default constructor Parameterized constructor Constructors with default arguments Copy constructors
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Default Constructors • Syntax class name{ public: name( ){ // executable statements; } };
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Default Constructors • • • •
Contd …
BankAccount ( ) { constructor min_bal = 5000; acc_num = 2004; }
// default
Using the member initialization list : 5. BankAccount ( ) : min_bal( 5000 ) , acc_num( 2004 ) 6. { }
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Parameterized constructor (unsigned x) : min_bal ( 5000 ) , acc_num ( x ) { }
BankAccount
(double bal,unsigned x) : min_bal (bal) , acc_num(x) { }
BankAccount
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Constructor Overloading • class BankAccount { //default access is private. • unsigned acc_num; • double balance; • public: • BankAccount( ):balance(5000),acc_num(2004) • {} • BankAccount(unsigned x):balance(5000),acc_num(x) • {} • BankAccount(double bal,unsigned x):balance(bal),acc_num(x) • {} • void deposit(double amt){ • balance+=amt; • } • void withdraw(double amt){ • balance-=amt; • } • void display( ){ • cout<<"Account NUMBER-"<
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Constructor Overloading
Contd …
• • • •
int main( ){ BankAccount B1; B1.deposit(3500); B1.display( );
•
BankAccount B2(3005); //BankAccount B2=3005; B2.deposit(8000); B2.display( );
• • • •
return 0; }
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Constructors with default arguments • • • • • • •
//BankAccount (unsigned x):balance(5000),acc_num(x) //{ } //BankAccount (double bal, unsigned x): balance ( bal ), acc_num (x) //{ } BankAccount (unsigned x ,double bal=5000):balance(bal),acc_num(x) {}
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Explicit keyword • • • • • • •
#include
class BankAccount{ unsigned acc_num; double balance; public: explicit BankAccount ( unsigned x ): balance ( 5000 ), acc_num (x) • {} • bool compare_bal ( BankAccount s ){ return s.balance > balance; } • void deposit(double amt){ • balance+=amt; • } • void withdraw(double amt){ • balance-=amt; • } • void display(){ • cout<<"Account NUMBER-"<
Explicit keyword
Contd …
1. int main( ){ 2. BankAccount B2=3005; //error 3. B2.deposit(8000); 4. cout<<"\nB2 details...."<<endl; 5. B2.display( ); 7. 8. }
return 0;
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Copy constructor • Used to declare and initialize an object from another object Syntax to declare: class_name ( class_name &); Syntax to invoke c’tor: class_name new_object = source_object; OR class_name new_object(source_object); Pragati Software Pvt. Ltd., 312, Lok Center, Marol-Maroshi Road, Marol, Andheri (East), Mumbai 400 059. www.pragatisoftware.com
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Copy constructor example • • • • • • • • • • • • • • • • • • •
class BankAccount{ unsigned acc_num; unsigned balance; public: BankAccount():balance(5000),acc_num(2004) {} BankAccount(BankAccount &obj):balance(obj.balance),acc_num(2005) {} void deposit(unsigned x){ balance+=x; } void withdraw(unsigned x){ balance-=x; } void display( ){ cout<<"Account NUMBER-"<
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Copy constructor example • • • • •
Contd …
int main( ){ BankAccount B1; cout<<"\nB1 deposits 3500\n"; B1.deposit(3500); B1.display( );
• • •
BankAccount B2(B1); // invoking copy ctor cout<<"\nB2 cloned B1...."<<endl; B2.display( );
• • •
cout<<"\n"; return 0; }
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Dynamic Allocation • Used to allocate memory to objects at runtime • Memory can be allocated using the new operator Eg: int *pi=new int; int *pia = new int[10]; LinkList *ptr = new LinkList( );
• Memory can be de-allocated using the delete operator delete ptr
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Dynamic Allocation
Contd …
1. class BankAccount 2. { 3. unsigned acc_num; 4. double balance; 5. public: 6. BankAccount(unsigned x,double bal) : acc_num ( x ), balance ( bal ) 7. {} 8. void display( ) 9. { 10. cout<
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Dynamic Allocation • • • • • • •
Contd …
int main( ) { BankAccount *ptr=new BankAccount(333,3500); ptr- rel="nofollow">display( ); delete ptr; return 0; }
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Destructors • Automatically called when an object is destroyed . • Syntax class name{ public: name( ){ // executable statements; } ~name( ){ // executable statements; } }; Pragati Software Pvt. Ltd., 312, Lok Center, Marol-Maroshi Road, Marol, Andheri (East), Mumbai 400 059. www.pragatisoftware.com
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Destructors Example • • • • • •
class BankAccount { unsigned acc_num; double balance; public: BankAccount( unsigned x, double bal) : acc_num ( x ) , balance( bal ) • { } • ~BankAccount( ) • { • cout<<"This is the bank account destructor!"<<endl; • } • void display( ){ • cout<
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Destructors Example
Contd…
1. int main( ) 2. { 3. cout<<"For object created on the heap..."<<endl; 4. BankAccount *ptr=new BankAccount(333,3500); 5. delete ptr; 7. 8. 9. 10. }
cout<<endl<<"For temporary object"<<endl; BankAccount B1(334,4500); return 0;
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Static Data Members Syntax to declare: static data-type data_member;
Syntax to assign a value: Outside the class: data-type ClassName :: data_member = value;
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Static Member functions • Can access only other static members of the same class Syntax to declare: return_type static function_name(argument_list) ; Syntax to access: object::function_name(argument_list);
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Static Data Members and Member Functions Example • • • • • • • • • • • • • • • • • • • •
class BankAccount { unsigned acc_num; double balance; static int num; public: BankAccount ( ){ acc_num=450; balance=5000.0; ++num; } BankAccount ( unsigned x, double bal){ acc_num=x; balance=bal; ++num; } void deposit ( double amt){ balance+=amt; } static void showNoObjects( ){ cout<<"\nThe total number of objects created are:"<
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Static Data Members and Member Functions Example • • • • •
void display( ){ cout<<"\nAccount NUMBER-"<
• • • •
int main( ){ BankAccount S1; S1.deposit( 3500 ); S1.display( );
•
BankAccount S2(451,3005); // BankAccount S2=3005; • S2.deposit( 8000 ); • S2.display( ); • BankAccount::showNoObjects( ); • cout<<endl; • return 0; Pragati • Software } Pvt. Ltd., 312, Lok Center, Marol-Maroshi Road, Marol, Andheri (East), Mumbai 400 059. www.pragatisoftware.com
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Const Objects and const Member functions • • • • • • • • • • • • • • • • • •
class Time{ int hr,min,sec; public: Time(int h,int m,int s) { hr=h; min=m; sec=s; } void setTime(int h,int m,int s) { hr=h; min=m; sec=s; } void display( ) const { cout<<endl<<"the time is:"; cout<
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Const Objects and const Member functions •
Time const noon (12,0,0 ) ; object
• • • • • • •
int main( ) { noon.display( ); noon.setTime(5,6,7); cout<<endl; return 0; }
//Const
//will be an error ;
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Mutable keyword • • • • • • • • • • • • • • • • • • •
•
class Time{ int hr, min, sec; mutable int hr1; public: Time (int h , int m ,int s){ hr=h; min=m; sec=s; } void setTime (int h, int m, int s) { hr=h; min=m; sec=s; } void display( ) const { hr1 = 2; cout<<endl<<"The time is:"; cout<
};
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Module 6: Friend keyword • Overview Friend Functions Friend Classes
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Friend functions • Used to access the private members of a class by nonmember functions Syntax for declaring: friend return_type function_name(argument list); Syntax for defining: function_name(argument list){ // Body of function } Syntax for calling: function_name(argument list); Pragati Software Pvt. Ltd., 312, Lok Center, Marol-Maroshi Road, Marol, Andheri (East), Mumbai 400 059. www.pragatisoftware.com
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Friend functions example • • • • • • • • • • • • • • • • • •
class Time{ int hr,min,sec; friend Time calculateTime(Time,Time); public: Time( ) { hr=0; min=0; sec=0; } Time(int hr1,int min1,int sec1) { hr=hr1; min=min1; sec=sec1; } void display( ){ cout<
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Friend functions example •
contd…
• • • • • • • •
//function calculateTime requires to access the private members of class Time Time calculateTime (Time t1,Time t2) { Time result; result.hr=t1.hr+t2.hr; result.min=t1.min+t2.min; result.sec=t1.sec+t2.sec; return result; }
• • • • • • • •
int main( ) { Time t1(3,3,5), t2(2,5,6) ; Time t3; t3=calculateTime(t1,t2); t3.display( ); return 0; }
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Friend classes • • • • • • • • • • • • • •
class Node{ int x; friend class LinkedList; public: Node( ) : x(100) {} }; class LinkedList { Node obj; public: void display( ){ cout<<"the value of x is:"<
• • • • • •
int main( ) { LinkedList ll; ll.display( ); return 0; }
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Module 7: Operator Overloading • Overview Overloading The Binary + operator Overloading The prefix operator Overloading The postfix operator
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Operator overloading • Facility to give mutiple meaning to the set of predefined operators. • Syntax for declaring return_type operator operator_symbol(argument_list);
• Syntax for defining return_type operator operator_symbol(argument_list){ }
• Syntax for calling class_object1 operator_symbol class_object2; Pragati Software Pvt. Ltd., 312, Lok Center, Marol-Maroshi Road, Marol, Andheri (East), Mumbai 400 059. www.pragatisoftware.com
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Operator Overloading • The following operators can be overloaded: + ^ += < rel="nofollow"> &&
= -= <= ||
* < & >= ++
/ > new << --
% != delete >> ()
Following operators cannot be overloaded: sizeof, . , :: , ?: Pragati Software Pvt. Ltd., 312, Lok Center, Marol-Maroshi Road, Marol, Andheri (East), Mumbai 400 059. www.pragatisoftware.com
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Operator Overloading • Operator Overloading can be done by two methods: As a member function As a friend function
• No of parameters a Unary operator takes If declared as a member function is none If declared as a friend function is one
• No of parameters a Binary operator takes If declared as a member function is one If declared as a friend function is two
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Overloading the Plus operator as a Member function
1. class Time{ 2. int hr, min, sec; • Time 3. public: operator+(Time t2) 4. Time( ) • { 5. { • Time result; 6. hr=0; • result.hr=hr+t2.hr; 7. min=0; • 8. sec=0; result.min=min+t2.mi 9. } n; 10. Time (int hr, int min, int • sec) { result.sec=sec+t2.sec 11. this->hr=hr; ; 12. this->min=min; • return result; 13. this->sec=sec; • } 14. } • }; 15. void display( ) { 16. cout<
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Overloading the Plus operator as a Friend function
• class Time{ • int hr, min, sec; • Time operator+(Time • public: t1,Time t2) • Time( ){ • { • hr=0; • Time result; • min=0; • result.hr=t1.hr+t2.hr; • sec=0; • • } result.min=t1.min+t2.mi • Time( int hr, int min, int n; sec){ • • this->hr= hr; result.sec=t1.sec+t2.sec; • this->min= min; • return result; • this->sec= sec; • } • } • void display( ){ • cout<
Operator Overloading Example The call for both methods: • • • • • • • • •
int main( ) { Time t1(3,3,5),t2(2,5,6); Time t3; t3=t1+t2; //this invokes the operator overloaded function t3.display(); cout<<endl; return 0; }
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Overloading the Prefix operator as a Member function
1. class Time{ • Time 2. int hr, min, sec; operator++( ) 3. public: • { 4. Time( ) • Time result; 5. { • result.hr=++hr; 6. hr=0; • 7. min=0; result.min=++min; 8. sec=0; • 9. } result.sec=++sec; 10. Time (int hr, int min, int sec) { • return result; 11. this->hr=hr; • } 12. this->min=min; • }; 13. this->sec=sec; 14. } 15. void display( ){ 16. cout<
Overloading the Prefix operator as a Friend function • • • • • • • • • • • • • • • • • •
class Time{ int hr, min, sec; public: Time( ){ hr=0; min=0; sec=0; } Time( int hr, int min, int sec){ this->hr= hr; this->min= min; this->sec= sec; } void display( ){
cout<
• • • • • • • •
Time operator++ (Time t) { Time result; result.hr=++t. hr; result.min=++t. min; result.sec=++t. sec; return result; }
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Operator Overloading for prefix operator Example The call for both methods: • • • • • • • • •
int main( ) { Time t2(2,5,6); Time t3; t3=++t2; //this invokes the operator overloaded function t3.display( ); cout<<endl; return 0; }
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Postfix operator overloaded As a member function: • • • • • • •
Time operator++ ( int){ Time result; result. hr= hr++; result. min= min++; result. sec= sec++; return result; }
As a friend function: • • • • • • •
Time operator++ (Time t, int){ Time result; result. hr=t. hr++; result. min=t. min++; result. sec= t. sec++; return result; }
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Module 8: Inheritance • Overview
Inheritance Access Specifier Single Inheritance Multiple Inheritance Hybrid Inheritance
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Inheritance • Creating a new class from an existing class • Syntax: class derived_class_name: access specifier baseClass_name { …… };
• Syntax for Multiple Inheritance class derived_class_name: access specifier baseClass1_name, access specifier baseClass2_name, … { …… Pragati Software Pvt. Ltd., 312,}; Lok Center, Marol-Maroshi Road, Marol, Andheri (East), Mumbai 400 059. www.pragatisoftware.com
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Inheritance Access Specifier Type of Access Specifier private
PRIVATE MEMBERS
PROTECTED MEMBERS
PUBLIC MEMBERS
Not Inherited
Inherited but become private members of derived class
Inherited but become private members of derived class
protected
Not inherited
Inherited but remain protected members of derived class
Inherited but become protected members of derived class
public
Not inherited
Inherited but remain protected members of derived class
Inherited but become public members of derived class
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Types of inheritance • • • •
Single Multilevel Multiple Hybrid
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Single Inheritance: The Base Class • • • • • • • • • • • • • • •
class BankAccount{ protected: int accNo; double balance; public: BankAccount( ) { accNo=0; balance=5000; } void display( ) { cout<<"Account Number:"<
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Single Inheritance
Contd…
1. int main( ) 2. { 3. SavingAccount S1(8.75f); 4. S1.display( ); 6. 7. }
return 0;
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Constructor Ordering 1.
SavingAccount S1(8.75f);
3. • • • •
class BankAccount { BankAccount( ) { accNo=0; balance=5000; } };
• • • • •
class SavingAccount : public BankAccount { SavingAccount(float rofI) { rateOfInterest=rofI; } };
invokes
invokes
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Constructor Ordering • • • • • • • • • • • • • • • • • •
contd…
class BankAccount{ protected: int accNo; double balance; public: BankAccount(int AccNO,double bal) { accNo=AccNO; balance=bal; } }; class SavingAccount : public BankAccount { float minimumBalance; float rateOfInterest; public: SavingAccount(int AccNO,double bal,float rofI):BankAccount(AccNO,bal) { rateOfInterest=rofI; } };
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Constructor Ordering
contd…
int main( ) { SavingAccount S1(204,10000.0,8.75f); S1.display( ); return 0; }
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Multiple Inheritance class Membership{ protected: char typeOfMembership; public: Membership( ) {} Membership(char type) { typeOfMembership=type; } void display() { cout<<"\nThe Membership is of
class SavingAccount { static float minimumBalance; float rateOfInterest; public: SavingAccount( ) {} SavingAccount(float rofI) { rateOfInterest=rofI;
} void display( ) { cout<<"\nThe rate of Interest applied is:"<
Multiple Inheritance • • • • • • • •
Contd…
class LoanAccount: public Membership, public SavingAccount { }; int main( ) { LoanAccount B1; B1.display( ); error! return 0; }
//Ambiguity
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Hybrid Inheritance class BankAccount{ protected: int accNo; double balance; public: BankAccount( ) { accNo=0; balance=0; } BankAccount(int AccNo,double bal) { accNo=AccNo; balance=bal; } void display( ) { cout<<"Account Number:"<
Polymorphism Example int main( ) { BankAccount B1(203,10000.0); BankAccount *Baseptr=&B1; Baseptr- rel="nofollow">display( ); SavingAccount S1(204,3000.0,9.0f); Baseptr=&S1; Baseptr->display( );//calls SavingAccount.display() if display() is made virtual in base class, else calls BankAccount.display( ); CurrentAccount C1(5000.0); Baseptr=&C1; Baseptr->display( ); //calls CurrentAccount.display( ) if display( ) is made virtual in base class, else calls BankAccount.display( ); } Pragati Software Pvt. Ltd., 312, Lok Center, Marol-Maroshi Road, Marol, Andheri (East), Mumbai 400 059. www.pragatisoftware.com
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Abstract classes • No actual objects are created from it. • A class in C++ is abstract if it contains at least one pure virtual function • A virtual function equated to zero is called a pure virtual function
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Abstract classes Example class BankAccount{ protected: int accNo; double balance; public: BankAccount( ){ } BankAccount(int AccNo,double bal) { accNo=AccNo; balance=bal; } /*For making this function a pure virtual function it has to equated to zero*/ virtual void display( )=0; }; Pragati Software Pvt. Ltd., 312, Lok Center, Marol-Maroshi Road, Marol, Andheri (East), Mumbai 400 059. www.pragatisoftware.com
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Virtual Destructors class BankAccount { protected: int accNo; double balance; public: BankAccount( ){ } BankAccount(int AccNo,double bal) { accNo=AccNo; balance=bal; } /*For polymorphism this function has to declared as virtual*/ virtual void display( ){ cout<<"Account Number:"<
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Virtual Destructors class SavingAccount: public BankAccount { float minimumBalance; float rateOfInterest; public: SavingAccount ( int AccNo, double bal, float rofI) : BankAccount( AccNo, bal) { rateOfInterest = rofI; } void display( ) { BankAccount:: display( ); cout <<"\n The rate of Interest applied is:"<< rateOfInterest; } ~SavingAccount ( ){ cout<<"\nInvoking Saving account destructor..."; } }; int main( ){
BankAccount * Baseptr=new SavingAccount ( 204, 3000.0, 9.0f); delete Baseptr; } Pragati Software Pvt. Ltd., 312, Lok Center, Marol-Maroshi Road, Marol, Andheri (East), Mumbai 400 059. www.pragatisoftware.com
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Module 10: Streams • Overview
Stream class hierarchy cin.get ( )/ cin.getline( ) methods cin.ignore( ) method Manipulators
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Stream Classes A stream is a general name given to a flow of data in an input/output situation. Streams are called iostreams in C++ Advantages: No formatting characters in streams. Overloading of existing operators and functions possible
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Stream class hierarchy ios ostream
istream iostream ifstream
ofstream fstream
istream_ withassign
iostream_ withassign
ostream_ withassign
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Reading strings • Syntax
cin.get(signed char *s,int n,char_delim='\n');
cin.getline(signed char *s,int n,char_delim='\n')
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The get function 1. #include
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The getline function 1. 2. 3. 4. 5. 6. 7. 8. 9.
#include
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Limitations of the get and getline functions 1. int 2. { 3. 4. 5. 6. 7. 8. 9. 10. 11.}
main( ) char str[30]; int code; cout<<"Enter the code of the Employee "; cin>>code; cout<<"Enter the name of the Employee "; cin.getline(str,30); cout<<str<<" has code:"<
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cin.ignore( ) • Extract and discard characters • Eg : cin.ignore(4,'\n'); cin.ignore(1); Syntax: istream& ignore ( streamsize n = 1, int delim = EOF );
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Using cin.ignore( ) 1. int 2. { 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. }
main( ) char str[30]; int code; cout<<"Enter the code of the Employee "; cin>>code; cin.ignore(4,'\n'); cout<<"Enter the name of the Employee "; cin.getline(str,30); cout<<str<<" has code:"<
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Manipulators •Special functions used to alter format parameters Manipulator
Parameter
endl
function ‘\n’
setprecision
Number of decimal digits to be displayed
precision
setfill
Fill character
fill
setw
Variable width
width
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Module 11: File I/O • Overview Opening/ Closing a file reading /writing to a file char-by-char reading /writing an object to a file
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File i/o • File stream classes declared in fstream in the namespace std ifstream Used for file input operations Derived class of istream ofstream Used for file output operations Derived class of ostream
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Opening/Closing a file • Two ways to open a file: using open function using the constructor • To close a file using close function
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Reading/Writing to File char-by-char • • • • •
#include
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Reading/Writing an object to a File #include
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Reading/Writing an object to a File int main( ) { Person P1,P2; cout<<"\nEnter the data.\n"; P1.getData( ); ofstream data("Person_data.DAT"); cout<<"\nNow writing into the file..."<<endl; data.write((char *)&P1,sizeof(Person)); data.close(); ifstream data1("Person_data.DAT"); cout<<"Now reading from the file..."<<endl; data1.read((char *)&P2,sizeof(Person)); cout<<"\nData read is..."<<endl; P2.displayData(); cout<<endl; }
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Module 12: Exception Handling • Overview
Simple Exception Handling Catch-All Handler Re-throwing an exception Catching class type exceptions Handling derived class exceptions Unwinding the stack Throwing exceptions from constructors Using set_terminate ( ) function
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Exception handling • Runtime Errors are called exceptions • C++ exception handling has three keywords: try catch throw
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Syntax of a try…catch try { …………. throw exception; …………. } catch(type1 arg) { //catch block } catch(type2 arg) { //catch block } catch(type3 arg) { //catch block } Pragati Software Pvt. Ltd., 312, Lok Center, Marol-Maroshi Road, Marol, Andheri (East), Mumbai 400 059. www.pragatisoftware.com
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Simple Exception Handling • •
#include
• • • • •
int main( ) { try{
• • • • •
cout<<"U R IN TRY BLOCK !!"<<endl; throw 10; //throw exception of type
integer. } catch(int){ //catch handler for integer. cout<<"U R IN CATCH BLOCK !!"<<endl; } }
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Catch-All Handler int main( ) { try{ int y; cout<<"\n\nIn try block..."; cout<<"Enter the value of y:"; cin>>y; if(y= =100) throw y; //throw an excepiton of type int else cout<<"The value entered is:"<
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Re-throwing an exception void func1( ) { try{ throw "SOMETHING went wrong !!!"; } catch ( const char *s){ cout<<"Inside internal handler !!"<<endl; cout<<"\n Rethrowing the exception to the calling function..."; throw; } }
int main( ) { try{ func1( ); } catch(const char *s){ cout<<"\nBack in function main !!"<<endl; cout<<s<<endl; } }
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Catching class type exceptions int main( ) { int num; try{ cout<<"Enter a number \n"; cin>>num; if(num<0) throw MyException("Not a positive number !!",num); else cout<<"The number is a positive number:"<
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Handling derived class exceptions class A{ }; class B{ }; //class C inherits from B and A class C: public B, public A{ }; C c; B b; A a;
int main( ) { try{ throw c;
} catch (C d) { cout <<"\n Catch of derived \n \n"; } catch ( B &a){ cout<<"\n Catch of base b \n"; } catch ( A &){ cout<<"\n Catch of base a\n"; } } Pragati Software Pvt. Ltd., 312, Lok Center, Marol-Maroshi Road, Marol, Andheri (East), Mumbai 400 059. www.pragatisoftware.com
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Unwinding the stack class Employee{ int acc_no; char name[10]; public: Employee(int x,char *str){ acc_no=x;
int main( ) { try{ Employee emp(1,"Sunil"); cout<<"\nException generated..."; throw 1; } catch ( int){ strcpy(name,str); cout<<"\n In Exception } Handler"<< endl; ~Employee( ){ } cout<<"\nIn the } destructor"; } };
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Throwing exceptions from constructors class Engineer{ public: Engineer( ){ cout<<"Inside } ~Engineer( ){ cout<<"Inside } }; class Manager{ public: Manager( ){ cout<<"Inside } ~Manager( ){ cout<<"Inside } };
Engineer constructor !!"<<endl; Engineer destructor !!"<<endl;
Manager constructor !!"<<endl; Manager destructor !!"<<endl;
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Throwing exceptions from constructors Contd… class EngineerManager : public Manager{ public: EngineerManager ( ){ cout<<"Inside EngineerManager constructor !! "<<endl; Engineer e; throw -1; } ~EngineerManager ( ){ cout<<"Inside EngineerManager destructor !! "<<endl; } }; int main( ){ try{ EngineerManager EM; } catch(int){ cout<<"CAUGHT AN ERROR"<<endl; } Pragati}Software Pvt. Ltd., 312, Lok Center, Marol-Maroshi Road, Marol, Andheri (East), Mumbai 400 059. www.pragatisoftware.com
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Using set_terminate ( ) function void Big_crunch ( ){ cout<<"UNEXPECTED ERROR IN APPLICATION !! "<<endl<< “Exiting to os"<<endl; exit(-1); } int main( ){ set_terminate ( Big_crunch); try{ throw 1; //throw exception of type int. } catch ( char ){ cout<<"CAUGHT IN BLOCK"; } return 0; } Pragati Software Pvt. Ltd., 312, Lok Center, Marol-Maroshi Road, Marol, Andheri (East), Mumbai 400 059. www.pragatisoftware.com
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Module 13: RTTI and Casting Operators • Overview
typeinfo class and using the typeid object dynamic_cast const_cast static_cast reinterpret_cast
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RTTI • RTTI: Run Time Type Identification. • This allows to identify object-type during program execution. • Syntax: typeid(object); • Uses #include
bool operator ==(const type_info &ob); bool operator !=(const type_info &ob); bool before(const type_info &ob); const char *name( );
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typeinfo class #include
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Using typeid int main( ){ int i,j; float f; char * chp; ClsBase obj1,*ptr=0; class2 obj2; ClsDerv d1,*dptr=0; cout<<"Data type of int i is:"<
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Using typeid if(typeid(i)==typeid(j)) cout<<"\nBOTH i and j are integers and of the same type"<<endl; if(typeid(i)==typeid(f)) cout<<"BOTH i and f are of the same type"<<endl; else cout<<"i and f are not the same type"<<endl; cout<<endl; if(typeid(obj1)==typeid(obj2)) cout<<"BOTH obj1 and obj2 are of the same type"<<endl; else cout<<"obj1 and obj2 are not the same type"<<endl; cout<<endl; cout<<"\nThe number preceding the name indicates the number of characters in the class name "<<endl; cout<<"The type of obj1 is:"<
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Using typeid cout<<"The type of obj1 is:"<
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Casting Operators • Explicit Casting operators • Syntax: cast_name
dynamic_cast static_cast const_cast reinterpret_cast
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dynamic_cast class Base { public: virtual void display( ) { cout<<"In base"; } }; class Derived:public Base { public: void display( ) { cout<<"In Derived"; } };
void main( ){ Base *bp; Derived *dp, d; bp = &d; if(!bp) cout<<"Casting failed"; dp = dynamic_cast
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const_cast • • • • • •
int square ( const int *val){ int *ptr; ptr = const_cast
• • • • • •
int main( ){ int num=5; cout<<"Number:"<
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static_cast • • • • • • • • • • •
int main( ) { int cnt; double tmp; for(cnt=1; cnt<=10; cnt++) { tmp = static_cast<double> (cnt)/2; cout<
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reinterpret_cast • • • • • • • •
int main( ){ int num=100, add; int *ptr = # cout<<"num address:"<<(int)# add = reinterpret_cast
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Module 14: Templates • Overview Template Function with one argument Template Function with two arguments Class Templates
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Templates • Syntax for Function Template: template
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Template Function with one argument • • • • • • • • • •
template
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Template Function with two arguments • • • • • • • • • • • • • • • • •
template
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Class Template • #include
1. void pop( ){ 2. if(top>=0) { 3. cout<<"Popping..."<<endl; • template
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Class Template
• cout<<"Stack of strings....."<<endl; • int main( ) • Stack<string> S2; • { • S2.push("Hi"); • cout<<"Stack of • S2.push("Hello"); Integers....."<<endl; • S2.push("What's"); • Stack
Defining Member functions of Class Templates • template
• • • • •
cout<<"Stack Overflow!!"; } template
cout<<"Popping..."<<endl; • top--; • } • else • cout<<"Stack is • template
253
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