Lect26 Basics of C Programming

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COMPUTER PROGRAMMING I

(TA C162)

Lecture 26 – Basics of C Programming



Today’s Agenda

Structure of a C program

2



Our Text Book

Saturday, March 20, 2010 Biju K Raveendran@BITS Pilani. 3



About C General purpose structured programming

language

Characterized b the abilit to write ver

concise source program

Comparatively small instruction set

Programs are highly portable

4



Structure of a C Language Program/* Program to compute …………………………. */

#include<stdio.h>

/*Library files inclusion *//* Global variable declaration …………………*/

{

/* local variable declarations */

/* initialization */

/* statements */

re urn ;}

5



Structure of a C Program very program cons s s o one or more mo u es ca efunctions.

One of the functions must be called main.

Execution will always begin by main.

Each compound statement is enclosed within a pair ofbraces

{

Statement1;

Statement2;………

}

Each statement must end with a semicolon (;)

Anything within /* */ treated as comments Comments may appear anywhere within program

6



Our first C Program/* Converts the distance from miles to kilometer

*/

#include <stdio.h>

_ _ .

int main(void){

double miles, kms;

/*get the distance in miles*/

printf(“ Enter the distance in miles : ” );

scanf(“ %lf” ,&miles );conver e s ance o ome ers

kms=KMS_PER_MILE * miles;

/* Display the result in kilometers*/

“ ” ,

return(0);

}




*/

#include <stdio.h>

Comments

_ _ .

int main(void){

double miles, kms;

ny ng e ween

is interpreted ascomment and is



scanf(“ %lf” ,&miles );

compiler

conver e s ance o ome ers



“ ”

escr es e ey

operations of the

program ,

return(0);

} Note: Placing one

comment inside the



Comments in C Used for improving readability of the program

compiler

/* line(s) of text ……. */

All the text between /* and */ are commented

// One line of text

Commented the text till the end of that line





*/

#include <stdio.h>

Preprocessor Directives:

Modifies the C program

before the com ilation _ _ .

int main(void){

double miles, kms;

begin #include directive gives a

ro ram access to a librar /*get the distance in miles*/



stdio.h is a standard Cconver e s ance o ome ers



“ ”

In this program, it supports

printf, scanf functions

,

return(0);

} Each l ibrary has a standard

header fi le whose name

ends with .h




*/

#include <stdio.h>

Function Main:

_ _ .

int main(void){

double miles, kms;

function where theexecution begins




Every C program has a

main functionconver e s ance o ome ers



“ ”

The remaining lines

(function body) of the,

return(0);

}

within the braces { }




*/

#include <stdio.h>

Function Main:

_ _ .

int main(void){

double miles, kms;

{function body




}

Function body has 2conver e s ance o ome ers



“ ”

parts

Declarations

Executable statements ,

return(0);

}



Tell the compiler the names of memory cells in aprogram

Example: miles, kms

Programmer uses the data requirement analysis

Executable statements

language instructions and executed by the computer





*/

#include <stdio.h>

int main(void)

Returns an integer to the

o eratin s stem after _ _ .

int main(void){

double miles, kms;

completing the main

function

Receives no data from the/*get the distance in miles*/



operating system before

it begins execution

conver e s ance o ome ers



“ ”

return(0) :

Returns the control from,

return(0);

}

operating system

Lect26 Basics of C Programming

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