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Introduction To C++ Programming Language
LECTURE
What is C++ C++ is a high-level language and it is evolved from C over a period of several years starting in 1980. The standard for C++ was jointly developed by the American National Standards Institute (ANSI) and the International Standards Organization (ISO). a set of rules, symbols, and special words used to construct a computer
Structure of a C++ Program
Figure 3.1 Structure of a C++ Program
A Typical C++ Program // A typical C++ Program
Comment
# include using namespace std; # define PI 3.142
Preprocessor Directive
int
Global Declaration
Integer;
int main ( ) { double radius, area; radius = 7; area = radius * radius * PI; return 0; }
Local declaration
Statements
Main function
Character Set C++ is composed of character set :
Number : 0 to 9
Alphabetical : a to z and A to Z
Spacing
Special Character :
, . : ; ? ! ( ) {} “ ‘ + - * / = > < # % & ^ ~ | / _
Token
Token : combination of the characters in C++
Categorised into:
Identifiers
Reserved words/keywords
Constants
Literal String
Punctuators
Operators
Identifiers
Allows programmers to name data and other objects in the program-variable, constant, function etc. Can use any capital letter A through Z, lowercase letters a through z, digits 0 through 9 and also underscore ( _ ) Rules for identifier The first character must be alphabetic character or underscore It must consists only of alphabetic characters, digits and underscores, cannot contain spaces It cannot duplicate any reserved word C++ is case-sensitive; this means that CASE, Case, case, and CaSe are four completely different words.
Valid and Invalid Identifiers Valid names A student_name _aSystemNam e pi al stdntNm _anthrSysNm PI
Invalid names $sum
// $ is illegal 2names // can’t start with 2 stdnt Nmbr // can’t have space int // reserved word
Reserved word/Keywords A word that has special meaning in C++. Keywords cannot be used to name identifiers.
Constant Data values that cannot be changed during the execution of a program Types of constant:
Literals constant Defined constants Declared constants
Literals Constant
If the data cannot be changed, we can simply code the data value itself in a statement Eg: discount = 0.10 ;
Categorised into:
0.10 is a literal constant
Integer Numerals ( eg: 178, -9, 0113, 0x4b) Floating-Point Numerals (eg: 3.14159,6.02e23,1.6e-19 ,3.0 Characters ( eg: ‘A’, ‘p’) Strings ( eg; “Hello World”) Boolean (eg: true , false).
Defined Constant (#define)
Use the #define preprocessor directive Format: #define identifier value Eg : #define EPF_RATE 0.11
Placed at the beginning of the program
#include using namespace std; #define EPF_RATE 3.142 int main() { ……; nett = salary – ( salary * EPF_RATE); ………; }
Declared Constants se a type const qualifier to indicate that data cannot be changed and to fix the contents of the memory location #include g: const float = 3.1416; using namespace std; #define EPF_RATE 3.142
eclared inside a function
int main() { const double socso_rate = 0.05; nett = salary – ( salary * EPF_RATE * socso_rate); ………; }
Data Types in C++
Type defines a set of value and operations that can be applied on those values
Set of values for each type is known as the domain for the type
Functions also have types which is determined by the data it returns
Data Types
Standard
They serves as the basic building blocks for derived types (complex structures that are built using the standard types
Serves as the basic building blocks for derived types
Data Types
Derived
Data Type : Void
Typed as void Has no values and operations Both set of values are empty Usually used in functions Eg:
void printSum()
Data Type : Char
Used to hold characters or very small integer values Usually 1 byte of memory CODE: char letter; letter = 'C';
Data Type : Integer
Coded as int A number without a fraction part C++ supports three different sizes of integer short
int
int long
int
Can be signed and unsigned
Data Type : Integer Maximum Value
Type
Byte Size
Minimum Value
short int
2
-32,768
32,767
unsigned short int
2
0
65,535
int
4
-2,147,483,648
2,147,483,647
unsigned int
4
0
4,294,967,295
long int
4
-2,147,483,648
2,147,483,647
unsigned long int
4
0
4,294,967,295
Data Type : Float
A number with fractional part such as 43.32, - 2.33 C++ supports three types of float float double long float Stored in a form similar to scientific notation Can be represented in Fixed point (decimal) notation: 31.4159 0.0000625 E notation: 3.14159E1 6.25e-5
Data Type Float
Are double by default Can be forced to be float (3.14159f) or long double (0.0000625L)
All floating-point numbers are signed
Range
Type
Byte Size
Precision
float
4
7
10-37 ..1038
double
8
15
10-307 ..10308
long double
8
15
10-307 ..10308
Data Type : Boolean
Represents values that are true or false
bool variables are stored as small integers
false is represented by 0, true by 1: bool allDone = true; bool finished = false; allDone finished
0
Variables
A storage location in memory whose contents can change while program is running Has an identifier and a type of data it can hold Variable declaration syntax :
type identifier [= initial_value] eg : int itemsOrdered;
To hold the number of items ordered.
A variable name should represent the purpose of the variable.
Variables
Variables Initialization
To initialize a variable means to assign it a value when it is declared: int length = 12;
Can initialize some or all variables: int length = 12, width = 5, area;
Variables Assignment
An assignment statement uses the = operator to store a value in a variable. item = 12; This statement assigns the value 12 to the item variable. The variable receiving the value must appear on the left side of the = operator. This will NOT work: // ERROR! 12 = item;
Variables Scope
The scope of a variable: the part of the program in which the variable can be accessed
A variable cannot be used before it is defined
Variables Scope
Global Variables
Local Variable
Local Variable
Variables Scope
Global scope a global variable is a variable declared in the main body of the source code, outside all functions Global variables can be referred from anywhere in the code, even inside functions, whenever it is after its declaration.
Local Scope a
local variable is one declared within the body of a function or a block. is limited to the block enclosed in braces ({}) where they are declared.
Operators
C ++ uses a set of built in operators ( Eg : +, -, / etc). Four classes of operators : Arithmetic Relational Logical Assignment
Arithmetic Operators
Assume int a=4, b= 5, d; C++ Operation
Arithmetic Operator
C++ Expression
Value of d after assignment
Addition
+
d=a+b
9
Substraction
-
d=b-2
3
Multiplication
*
d=a*b
20
Division
/
d = a/2
2
Modulus
%
d = b%3
2
Assignment Operators
Assume x=4, y=5, z=8; Assignment Operator
Sample Expression
Similar Expression
Value of variable after assignment
+=
x += 5
x=x+5
x=9
-=
y -= x
y=y-x
y=1
*=
x *= z
x = x*z
x=32
/=
z /=2
z = z/2
z=4
y = y%x
y=1
%=
y %=x
Relational & Equality Operators
Assume y = 6, x =5 Relational Operators
Sample Expression
Value
>
y>x
T
<
y<2
F
>=
x >= 3
T
<=
y <= x
F
Equality Operators
Sample Expression
Value
==
x == 5
T
!=
y !=6
F
Logical Operators Logical Operators
Called
Sample Operation
&&
AND
expression1 && expression 2
||
OR
expression1 | | expression2
!
NOT
!expression
Example :Assume int x = 50 expression
!expression
Sample Expression
F
T
!(x == 60)
T
F
!(x != 60)
Logical Operators
Assume x=4, y=5, z=8 Sample Expression
expression1
expression2
expression1 && expression2
F
F
F
( y > 10) && ( z <=x )
F
T
F
( z <= y) && ( x == 4)
T
F
F
( y != z) && ( z < x )
T
T
T
( z >= y ) && ( x != 3 )
Increment and Decrement Operators Operator
Called
Sample Expression
Similar Expression
Explanation
++
preincrement
++a
a = a +1
Increment a by 1, then use the new value of a in expression in which a reside
a += 1 ++
postincrement
a++
a = a +1 a += 1
--
predecrement
--a
a = a -1 a -= 1
--
postdecrement
a--
a = a -1 a -= 1
Use the current value of a in the expression which a reside, then increment a by 1 Decrement a by 1, then use the new value of a in expression in which a reside Use the current value of a in the expression which a reside, then decrement a by 1
Operator Precedence Operators
Associative
()
Left to right
++ - - + - !
Right to left
* / %
Left to right
+ -
Left to right
< <= > >=
Left to right
= = !=
Left to right
&&
Left to right
||
Left to right
*= += - = /= %=
Right to left
Operator Precedence Example 1:
Example 2:
int a=10, b=20, c=15, d=8;
int a=15, b=6, c=5, d=4;
a*b/(-c*31%13)*d
d *= ++b – a/3 + c
1.
a*b/(-15*31%13)*d
1. d *= ++b – a/3+ c
2.
a*b/(-465%13)*d
2. d*=7- a/3+c
3.
a*b/(-10)*d
3. d*=7- 5+c
4.
200/(-10)*d
4. d*=2 + c
5.
-20*d
5. d*= 7
6.
-160
6. d = d*7 7. d = 28
Example of a program // Operating with variables #include using namespace std; int main() { //variables declaration int no1; int no2; int value_div; int value_mod; cout << “Enter two integral numbers:”; cin >> no1 >> no2; value_div= no1 / no2; cout << no1 << “ / ” << no2 << “ is ” << value_div; value_mod = no1 % no2; cout << “ with a remainder of ” << value_mod << endl; return 0; }
Output : Enter two integral numbers : 10 6 10 / 6 is 1 with a remainder of 4
/*Evaluate two complex expression*/ #include using namespace std; void main ( ) { int a =3, b=4, c = 5, x, y; cout << “Initial values of the variables:\n”; cout << “a = “ << a<< “ b = “ << b <<“ c = “ << c<< endl; cout << endl;
Output : Initial values of the variables : a=3
b=4 c= 5
x = a * 4 + b / 2 – c * b; cout << “Value of a * 4 + b/2-c * b is : “ << x << endl; y = - - a * (3 + b) / 2 – c++ * b;
Values of the variables are now :
cout << “Value of - - a * (3 + b) / 2 – c++ * b is: “
a=2
<< y << endl; cout << “a = “ << a << “ b = “ << b << “ c = “ << c << endl; }
Value of a * 4 + b/2-c * b is : -6 Value of - - a * (3 + b) / 2 – c++ * b is: -13
b=4 c= 6
Formatting Output
Output is made more readable using manipulator
Must include header file. Manipulators endl dec oct hex fixed showpoint setw(…) setprecision setfill(…)
Use New line Formats output as decimal Formats output as octal Formats output as hexadecimal Set floating-point decimals Shows decimal in floating-point values Sets width of output fields Specifies number of decimals for floating point Specifies fill character
Formatting Output
Set Width (setw) Set the minimum width for an output Two alignment : right justified and left justified
Set Fill Character (setfill) If
the output width is greater than the data values placed in it, a fill character can be used to fill the empty spaces whenever required
Formatting Output
Three integer manipulators: Decimal
(dec)
The
default Value in decimal form
Octal (oct) Values
are displayed in octal numbering system
Hexadecimal Values
(hex)
are in hexadecimal format
Formatting Output
Three Floating-point manipulators: Fixed (fixed)
Displays floating-point numbers (eg: 1.234568e+6) in the fixed-point format (1234567.875)
Set precision (setprecision) Used
to control the number of the decimal places to be displayed
Showpoint (showpoint) To
show value with the decimal point
//demonstrate the output manipulator #include #include using namespace std; int main( ) { char aChar; int integer; float dlrAmnt;
Output : cout << “Please enter an integer ,\n”; << “ a dollar amount and a character.\n”; cin >> integer>>dlrAmnt >> aChar;
cout <<“\nThank you.You entered:\n”; cout << setw( 6 ) << integer << “ “ << setfill(‘*’) << setprecision (2) << fixed << ‘$’ << setw(10) << dlrAmnt << setfill(‘ ‘) << setw( 3 ) <
}
Please enter an integer, a dollar amount and a character. 12 123.45 G
Thank you. You entered: 12 $****123.45 G
THANK YOU!
LECTURE
What is C++ C++ is a high-level language and it is evolved from C over a period of several years starting in 1980. The standard for C++ was jointly developed by the American National Standards Institute (ANSI) and the International Standards Organization (ISO). a set of rules, symbols, and special words used to construct a computer
Structure of a C++ Program
Figure 3.1 Structure of a C++ Program
A Typical C++ Program // A typical C++ Program
Comment
# include
Preprocessor Directive
int
Global Declaration
Integer;
int main ( ) { double radius, area; radius = 7; area = radius * radius * PI; return 0; }
Local declaration
Statements
Main function
Character Set C++ is composed of character set :
Number : 0 to 9
Alphabetical : a to z and A to Z
Spacing
Special Character :
, . : ; ? ! ( ) {} “ ‘ + - * / = > < # % & ^ ~ | / _
Token
Token : combination of the characters in C++
Categorised into:
Identifiers
Reserved words/keywords
Constants
Literal String
Punctuators
Operators
Identifiers
Allows programmers to name data and other objects in the program-variable, constant, function etc. Can use any capital letter A through Z, lowercase letters a through z, digits 0 through 9 and also underscore ( _ ) Rules for identifier The first character must be alphabetic character or underscore It must consists only of alphabetic characters, digits and underscores, cannot contain spaces It cannot duplicate any reserved word C++ is case-sensitive; this means that CASE, Case, case, and CaSe are four completely different words.
Valid and Invalid Identifiers Valid names A student_name _aSystemNam e pi al stdntNm _anthrSysNm PI
Invalid names $sum
// $ is illegal 2names // can’t start with 2 stdnt Nmbr // can’t have space int // reserved word
Reserved word/Keywords A word that has special meaning in C++. Keywords cannot be used to name identifiers.
Constant Data values that cannot be changed during the execution of a program Types of constant:
Literals constant Defined constants Declared constants
Literals Constant
If the data cannot be changed, we can simply code the data value itself in a statement Eg: discount = 0.10 ;
Categorised into:
0.10 is a literal constant
Integer Numerals ( eg: 178, -9, 0113, 0x4b) Floating-Point Numerals (eg: 3.14159,6.02e23,1.6e-19 ,3.0 Characters ( eg: ‘A’, ‘p’) Strings ( eg; “Hello World”) Boolean (eg: true , false).
Defined Constant (#define)
Use the #define preprocessor directive Format: #define identifier value Eg : #define EPF_RATE 0.11
Placed at the beginning of the program
#include
Declared Constants se a type const qualifier to indicate that data cannot be changed and to fix the contents of the memory location #include
eclared inside a function
int main() { const double socso_rate = 0.05; nett = salary – ( salary * EPF_RATE * socso_rate); ………; }
Data Types in C++
Type defines a set of value and operations that can be applied on those values
Set of values for each type is known as the domain for the type
Functions also have types which is determined by the data it returns
Data Types
Standard
They serves as the basic building blocks for derived types (complex structures that are built using the standard types
Serves as the basic building blocks for derived types
Data Types
Derived
Data Type : Void
Typed as void Has no values and operations Both set of values are empty Usually used in functions Eg:
void printSum()
Data Type : Char
Used to hold characters or very small integer values Usually 1 byte of memory CODE: char letter; letter = 'C';
Data Type : Integer
Coded as int A number without a fraction part C++ supports three different sizes of integer short
int
int long
int
Can be signed and unsigned
Data Type : Integer Maximum Value
Type
Byte Size
Minimum Value
short int
2
-32,768
32,767
unsigned short int
2
0
65,535
int
4
-2,147,483,648
2,147,483,647
unsigned int
4
0
4,294,967,295
long int
4
-2,147,483,648
2,147,483,647
unsigned long int
4
0
4,294,967,295
Data Type : Float
A number with fractional part such as 43.32, - 2.33 C++ supports three types of float float double long float Stored in a form similar to scientific notation Can be represented in Fixed point (decimal) notation: 31.4159 0.0000625 E notation: 3.14159E1 6.25e-5
Data Type Float
Are double by default Can be forced to be float (3.14159f) or long double (0.0000625L)
All floating-point numbers are signed
Range
Type
Byte Size
Precision
float
4
7
10-37 ..1038
double
8
15
10-307 ..10308
long double
8
15
10-307 ..10308
Data Type : Boolean
Represents values that are true or false
bool variables are stored as small integers
false is represented by 0, true by 1: bool allDone = true; bool finished = false; allDone finished
0
Variables
A storage location in memory whose contents can change while program is running Has an identifier and a type of data it can hold Variable declaration syntax :
type identifier [= initial_value] eg : int itemsOrdered;
To hold the number of items ordered.
A variable name should represent the purpose of the variable.
Variables
Variables Initialization
To initialize a variable means to assign it a value when it is declared: int length = 12;
Can initialize some or all variables: int length = 12, width = 5, area;
Variables Assignment
An assignment statement uses the = operator to store a value in a variable. item = 12; This statement assigns the value 12 to the item variable. The variable receiving the value must appear on the left side of the = operator. This will NOT work: // ERROR! 12 = item;
Variables Scope
The scope of a variable: the part of the program in which the variable can be accessed
A variable cannot be used before it is defined
Variables Scope
Global Variables
Local Variable
Local Variable
Variables Scope
Global scope a global variable is a variable declared in the main body of the source code, outside all functions Global variables can be referred from anywhere in the code, even inside functions, whenever it is after its declaration.
Local Scope a
local variable is one declared within the body of a function or a block. is limited to the block enclosed in braces ({}) where they are declared.
Operators
C ++ uses a set of built in operators ( Eg : +, -, / etc). Four classes of operators : Arithmetic Relational Logical Assignment
Arithmetic Operators
Assume int a=4, b= 5, d; C++ Operation
Arithmetic Operator
C++ Expression
Value of d after assignment
Addition
+
d=a+b
9
Substraction
-
d=b-2
3
Multiplication
*
d=a*b
20
Division
/
d = a/2
2
Modulus
%
d = b%3
2
Assignment Operators
Assume x=4, y=5, z=8; Assignment Operator
Sample Expression
Similar Expression
Value of variable after assignment
+=
x += 5
x=x+5
x=9
-=
y -= x
y=y-x
y=1
*=
x *= z
x = x*z
x=32
/=
z /=2
z = z/2
z=4
y = y%x
y=1
%=
y %=x
Relational & Equality Operators
Assume y = 6, x =5 Relational Operators
Sample Expression
Value
>
y>x
T
<
y<2
F
>=
x >= 3
T
<=
y <= x
F
Equality Operators
Sample Expression
Value
==
x == 5
T
!=
y !=6
F
Logical Operators Logical Operators
Called
Sample Operation
&&
AND
expression1 && expression 2
||
OR
expression1 | | expression2
!
NOT
!expression
Example :Assume int x = 50 expression
!expression
Sample Expression
F
T
!(x == 60)
T
F
!(x != 60)
Logical Operators
Assume x=4, y=5, z=8 Sample Expression
expression1
expression2
expression1 && expression2
F
F
F
( y > 10) && ( z <=x )
F
T
F
( z <= y) && ( x == 4)
T
F
F
( y != z) && ( z < x )
T
T
T
( z >= y ) && ( x != 3 )
Increment and Decrement Operators Operator
Called
Sample Expression
Similar Expression
Explanation
++
preincrement
++a
a = a +1
Increment a by 1, then use the new value of a in expression in which a reside
a += 1 ++
postincrement
a++
a = a +1 a += 1
--
predecrement
--a
a = a -1 a -= 1
--
postdecrement
a--
a = a -1 a -= 1
Use the current value of a in the expression which a reside, then increment a by 1 Decrement a by 1, then use the new value of a in expression in which a reside Use the current value of a in the expression which a reside, then decrement a by 1
Operator Precedence Operators
Associative
()
Left to right
++ - - + - !
Right to left
* / %
Left to right
+ -
Left to right
< <= > >=
Left to right
= = !=
Left to right
&&
Left to right
||
Left to right
*= += - = /= %=
Right to left
Operator Precedence Example 1:
Example 2:
int a=10, b=20, c=15, d=8;
int a=15, b=6, c=5, d=4;
a*b/(-c*31%13)*d
d *= ++b – a/3 + c
1.
a*b/(-15*31%13)*d
1. d *= ++b – a/3+ c
2.
a*b/(-465%13)*d
2. d*=7- a/3+c
3.
a*b/(-10)*d
3. d*=7- 5+c
4.
200/(-10)*d
4. d*=2 + c
5.
-20*d
5. d*= 7
6.
-160
6. d = d*7 7. d = 28
Example of a program // Operating with variables #include
Output : Enter two integral numbers : 10 6 10 / 6 is 1 with a remainder of 4
/*Evaluate two complex expression*/ #include
Output : Initial values of the variables : a=3
b=4 c= 5
x = a * 4 + b / 2 – c * b; cout << “Value of a * 4 + b/2-c * b is : “ << x << endl; y = - - a * (3 + b) / 2 – c++ * b;
Values of the variables are now :
cout << “Value of - - a * (3 + b) / 2 – c++ * b is: “
a=2
<< y << endl; cout << “a = “ << a << “ b = “ << b << “ c = “ << c << endl; }
Value of a * 4 + b/2-c * b is : -6 Value of - - a * (3 + b) / 2 – c++ * b is: -13
b=4 c= 6
Formatting Output
Output is made more readable using manipulator
Must include
Use New line Formats output as decimal Formats output as octal Formats output as hexadecimal Set floating-point decimals Shows decimal in floating-point values Sets width of output fields Specifies number of decimals for floating point Specifies fill character
Formatting Output
Set Width (setw) Set the minimum width for an output Two alignment : right justified and left justified
Set Fill Character (setfill) If
the output width is greater than the data values placed in it, a fill character can be used to fill the empty spaces whenever required
Formatting Output
Three integer manipulators: Decimal
(dec)
The
default Value in decimal form
Octal (oct) Values
are displayed in octal numbering system
Hexadecimal Values
(hex)
are in hexadecimal format
Formatting Output
Three Floating-point manipulators: Fixed (fixed)
Displays floating-point numbers (eg: 1.234568e+6) in the fixed-point format (1234567.875)
Set precision (setprecision) Used
to control the number of the decimal places to be displayed
Showpoint (showpoint) To
show value with the decimal point
//demonstrate the output manipulator #include
Output : cout << “Please enter an integer ,\n”; << “ a dollar amount and a character.\n”; cin >> integer>>dlrAmnt >> aChar;
cout <<“\nThank you.You entered:\n”; cout << setw( 6 ) << integer << “ “ << setfill(‘*’) << setprecision (2) << fixed << ‘$’ << setw(10) << dlrAmnt << setfill(‘ ‘) << setw( 3 ) <
}
Please enter an integer, a dollar amount and a character. 12 123.45 G
Thank you. You entered: 12 $****123.45 G
THANK YOU!
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