To find out the structure of a C program, consider following
Example
#include<stdio.h> int main() { int sum; printf("Hello World, sum is : "); sum=sum1(2,2); printf("%d",sum); getchar(); return 0; } int sum1(int x, int y) { return x+y; }
Any C program generally having structure as :-
- Include Header Files
- Define Global Variables
- Define main Function
- Execute Statements, Call Other Functions
- Define Other Functions
If we consider the above program, then above lines are explained as :
Line Number | Explanation |
---|---|
1st | We have include header files which are necessary for inclusion because of printf() and other standard input output functions. |
2nd | To define main() function, it’s the first function that compiler executes and also the starting of out program because this functions is executed at first. Other statements are executed later on. |
3rd | Opening Curly Brace for starting main() function block. |
4th | A variable (sum) of type Integer is defined. |
5th | printf() is a standard function that is used to output data to the console output(computer screen). |
6th | integer sum is assigned value of 2 variables by calling the function sum1 with parameters 2,2 |
7th | to output sum to computer screen. |
8th | getchar() is a function which is used to stop computer screen after outputting a value, because if we don’t put it the screen disappear after output of text, so getchar() will wait to type a character from keyboard until output window will not be disappeared |
9th | A return code 0 is returned by function to the Operating system. So that the operating system knows that program executed successfully. (not necessary) |
10th | main function closed |
12th | sum1() function is defined with two temporary parameters. |
14th | sum of x and y is returned |