Programming Concepts C Language

PESIT – Dept. D off MCA

Subject Code: MCA 14

Programming Concepts & C Language.

Faculty: Mr. N. Guruprasad Head – Dept. Dept of MCA http://www.pes.edu

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Overview of flow of Subject

• Computer Concepts and Programming Concepts • Introduction of C • Fundamental Of C • Preprocessor • Decision Control Structures • Loop Control Structures • Functions Storage g Classes • Arrays and Pointers • Strings • Structure and Unions • Bitwise Operators • File Handling g http://www.pes.edu

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CORE COMPETENCE

• • • • • • •

Introduction to Computers. C Programming g g Language. g g Data Structures and Algo. OS Concepts. UNIX OS. Object Oriented Programming C++ Programming Language From Here?

S/W Engg. Graphics

Network

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Problem gy Solution Methodology ( Algorithm) Programming Language ( C, C++, etc.,)

Flowchart to go through problems Example

Program + Data Solve Result

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ALGOL 60 (International Committee -1960) CPL (Cambridge & Univ. Of London-1963)

DEVELOPMENT OF C

BCPL (Martin Richards-cambridge-1967) B (Ken Thompson,Bell Labs.1970) C (Dennis Ritchie,bell Labs.1972)

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• H H.L.L: L L: Better program efficiency. Ex: Fortran etc., • L.L.L.: Better machine efficiency. Ex: Assembly etc., Where does

C stands ?

LANGUAGES

PROGRAMMING LANGUAGES

HIGH LEVEL

C

( Problem Oriented )

LOW LEVEL ( Machine Oriented )

• Has relatively good programming efficiency, efficiency compared to L.L.L. • Has relatively good machine efficiency, compared to H.L.L. http://www.pes.edu

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EDITOR C SOURCE CODE C PREPROCESSOR

STAGES IN COMPILATION OF C PROGRAM

C COMPILER ASSEMBLY LANG. CODE ASSEMBLER OBJ CODE & LIB FILES LINKER EXECUTABLE CODE LOADER http://www.pes.edu

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• •

CHARACTERISTICS OF C

• • • •

No input output operations. It is a language of functions data types functions, types, assignments and flow controls. C iss noted oted for o its ts ab ability ty to perform pointer arithmetic. C functions are recursive by default. The code in C is grouped into blocks. C allows you to develop a program in i multiple lti l source files that are independently compiled.

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A fundamental does not differ from language to language. It still remains same. What differs is the syntax.

FUNDAMENTALS OF C

C Character set: • • • •

Character set A-Z Character set a-z Digits 0-9 Special p Characters like *,, +,, , ( , ) , < , > etc.,

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FUNDAMENTALS OF C

Identifiers: name given to various program elements. Ex: variables, functions, arrays. First character must always be a letter or underscore. Ex: area, tax_rate. Keywords: Words which are standard and have predefined meaning in C.Ex: C Ex: break, break printf, switch. Constant: C constant are also referred as data types. Two types of constant: primary and secondary. http://www.pes.edu

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TYPES OF C CONSTANTS

Integer Constant: • Must have at least one digit. • Should not contain decimal point. • Could be either +ve or _ve. Real Constants: Two forms 1. Exponential form: mantissa & exponent , they should be separated by letter e. 2. Fractional form Character constant: single character/digit. Ex. ‘A’ max length is one. http://www.pes.edu

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Values varies during program execution.

VARIABLES OF C

Integer variables Real variable Ch Character variable i bl

int n; float n; char h n;

Rules: • Length 1 to 8 char (depends) • First char should be alphabet. • No commas, no blank spaces. • No special symbols, only underscore.

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Achieved with the help of library Functions.

I/O / OPERATIONS IN C

scanf() : Allows you to input data from standard d d input i device. d i Ex: scanf(“%d”, &var); printf(): Allows you to output data on standard output device. Ex: printf(“%d”, var);

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How does C program look like? /* Sample Program */ main(){ i (){ printf(“\n Welcome to C”); }

STRUCTURE OF C PROGRAM

main(): Where C prg starts executing. \n: New line character. { }: Analogous to begin & end in PASCAL. /* */: Comment statement Spacing should be provided from the point of readability. http://www.pes.edu

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OPERATORS AND ITS HIERARCHY

Operators: p Operations Addition Subtraction Multiplication Division Remainder

C + * / %

PASCAL + * DIV MOD

Ex: on=ink on=ink*act/2+3/2*act+2+t; act/2+3/2 act+2+t; ink=3, act=2, t=2.2; O/P: on=9.2 Ex: s=qui*add/4-6/2+2/3*6/go; qui=2, add=4, go=3; O/p: s=-1 s= 1 http://www.pes.edu

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Ex: a=7//2*(3.14+2)*3/5

OPERATORS AND ITS HIERARCHY

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OPERATIONS

C

PASCAL

greater than

>

>

>=

>=

<

<

less than or equal to

<=

<=

equal to

==

=

not equal to

!=

<>

greater than or equal to

RELATIONAL OPERATORS

less than

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LOGICAL OPERATORS

OPERATIONS

C

PASCAL

Negation L i l AND Logical Logical OR

! && ||

NOT AND OR

S Synopsis i off LLogical i l AND & OR. OR T– True

F– False

LOGICAL AND T && T = T T && F = F F && T = F F && F = F

LOGICAL OR T || T = T T || F = T F || T = T F || F = F

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INCREMENT OPERATOR AND FORMAT SPECIFICATION

Increment operators: a = a + 1 is same as a+=1 OR a++ (post ( t iincrement) t) or ++a (pre increment) Similarly decrement operator. C be Can b used d for f prefix fi or suffix. ffi Format Specification: %d integer %f real, float %c character %s string %o octal %x hexadecimal %u unsigned integer http://www.pes.edu

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? VALIDITY OF CODE

Problem P bl 1: 1 main(){ int x; x=-3+4*5-6; printf(“\n x=%d”, xx=3+4%5-6; 3+4%5 6; printf(“\n x=%d”, x=-3*4%-6/5; printf(“\n i tf(“\ x=%d”, %d” x=(7+6)%5/2; printf(“\n x=%d”, }

x); x); x); ) x);

Sol: x=11, x 11, x x=1, 1, x x=0, 0, x x=1 1 http://www.pes.edu

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?

Problem 2: main(){ printf(“\n %d %o %x”,72,72,72); %x 72 72 72); } Sol: 72, 110(Octal),48(Hex).

VALIDITY OF CODE Problem 3: main(){ int a=5.99999, b=5.00001; printf(“ a=%d b=%d printf( b=%d”, a,b); a b); } Sol: a=5 b=5. http://www.pes.edu

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Problem 4:

? VALIDITY OF CODE

main(){ printf(“\n printf(“\n printf(“\n printf(“\n }

%d”, %d”, %d”, %d”,

4/3); 4/-3); -4/3); -4/-3);

Sol: 1, -1, -1, 1; Note: One of them is –ve it will give –ve result.

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? VALIDITY OF CODE

P bl Problem 5: 5 main(){ printf(“\n printf(“\n printf(“\n printf( \n printf(“\n }

%d”, %d”, %d %d”,, %d”,

4%3); 4%-3); -4%3); 4%3); -4%-3);

Sol: 1, 1, -1, -1 Note: one or both –ve result takes sign of the numerator.

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? VALIDITY OF CODE

Problem P bl 6: 6 main(){ printf(“ Hello, world “ ); } Sol: Compilation error Unterminated String / Char Const. Problem 7: main(){ printf(“ Hello world” ) ; } Sol: Hello world http://www.pes.edu

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? VALIDITY OF CODE

Problem P bl 8: 8 main(){ int i = 5; printf (“%d“, i = i == 6 ); } Sol: 0 Problem 9: Will there th be b any error? ? main(){ { { } } } Sol: No http://www.pes.edu

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? VALIDITY OF CODE

Problem P bl 10 : main(){ int a,b=2,c; a=2*(b++); c=2*(++b); printf (“ %d %d %d“, a,b,c); } Sol: 4 4 8

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? VALIDITY OF CODE

P bl Problem 11 : main(){ i (){ int k=35; printf(“\n %d %d %d “, k==35,k=50,k>40); }

Sol: 0 50 0

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HOW ABOUT ASSIGNMENTS

1) How should I decide which integer type to use 2) Under my compiler this code prints 49 int i=7; printf(“%d”,i++ p ( , * i++); );

Regardless of the order of evaluation, should’nt it print 56. 3) Is it safe to assume that the right hand side of the && and || operators won won’tt be evaluated if the left hand side determines the outcome. http://www.pes.edu

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HOW ABOUT ASSIGNMENTS ( cont )

4) P People l keep k saying i that the behavior of i = i++ is undefined, but I just tried it on an ANSI conforming compiler and got the results I expected. 5) If I’m not using the value of the expression, should I use i++ or ++I to increment a variable. 6) Y does’nt does nt this code work : int a=1000,b=1000; long int c c=a*b; a b; http://www.pes.edu

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HOW ABOUT ASSIGNMENTS (cont)

7) H How do d I round d off ff th the numbers. 8) Y does’nt C have an exponentiation ti ti operator. 9) What is top down d i design methodology. th d l What R its advantages. 10) How does operation of an interpreter i t t differ diff from compiler.

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PREPROCESSOR

“ It is a program that preprocesses the source code, before it passes through compiler. Operates under what is called as P Preprocessor C Command d lines li or Directives ” Begins with #(hash) symbol and do not requires semicolon at the end.

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PREPROCESSOR

Grouped under three categories: • File Inclusion Directives : Achieved by # include. Syntax: #include Ex: #include<stdio.h> • Macro Substitution : Identifier in a program is replaced by some predefined strings composed of tokens. Ex: #define MAX 100 • Compiler Control : Selectivelyy removing g the code sections or choosing form two sections. Such process called as Conditional Compilation. http://www.pes.edu

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PREPROCESSOR

Ex: - - main(){ --#ifdef IBM-PC { ----/* code for IBMPC *// } #else{ ----/* code for HP */ } #endif } To run prg on IBM-PC we include: #define IBM IBM-PC. PC. http://www.pes.edu

P bl Problem 1:

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? VALIDITY OF CODE

#define PRODUCT(x) (x*x) (x x) main(){ int i=3,j; j PRODUCT(i+1); j=PRODUCT(i+1); printf(“\n %d “,j); }

Sol : 7

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P bl Problem 2:

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? VALIDITY OF CODE

#define PRODUCT(x) (x*x) (x x) main(){ int i=3,j,k; j PRODUCT(i++); j=PRODUCT(i++); k=PRODUCT(++i); printf(“\n %d %d“,j,k); }

Sol : 9 49

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Q Questions ti

What do U mean by a platform. How do U classify computer according to logic use. How do U classify computer according to size. Diff. b/w : RAM & ROM PROM & EPROM Different generations Batch & Transaction processing Hardware Software & its classification

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Internet What it is Who made it WWW / Web server etc Internet & Intranet

Q Questions ti ( contt )

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A i Assignments t :

Explain the organization of the digital computer. What is the need for secondary storage devices. Write note on hard disk. Explain the working principle of different d e e t types o of p printers. te s What is an O.S. Explain its various functions. Diff b/w : Diff. Assemble & HLL What is Computer N/w. Explain briefly different types of nw nw.

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A i Assignments t ( contt ) :

Differentiate between primary memory and secondary memory. Explain input and output devices along with examples. Define : OS O.S Compiler Interpreter Editor Edit Explain features of UNIX O.S Note on Internet & E-mail.

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Logic is very important in programming. Consider the following procedure of washing clothes using a washing machine.

Fl Flowchart h t Example E l :

1) Put P the h clothes l h in i the h washtub. 2) Pour water. 3) Pour detergent powder. powder 4) Switch on the washing machine. 5) Set the timer and wait f a few for f minutes. i t 6) Drain the water out. 7) End.

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This procedure gets the work k done. d Now, suppose the same steps are performed in a slightly different order.

Fl Flowchart h t Example E l ( cont ) :

1) Put the clothes in the washtub. h b 2) Switch on the washing machine. 3) Set the timer and wait for a few minutes. 4) Pour water. 5) Pour detergent powder. 6) Drain the water out. 7) End.

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In this case, case your clothes may tear off, since you have switched on the washing machine before pouring water into it.

Fl Flowchart h t Example E l

If you apply the above analogy to programming, you should carefully think about the order in which the instructions are carried out by your computer. This is precisely what logic is all about.

( cont ) :

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