Functions in C

C function is that block of code which does one or some tasks with specified purpose.

Basic Structure of Functions

return_ data_type Name of function(arg1, arg2)
    data _type _declarations of arguments;
    {

       Body of Function

    }

This program has function named 'sum' which sums the value of two numbers and returns to the main function. 

;This Simple Program Calculates Factorial of Number.

#include <stdio.h> //header file

#include<conio.h>//header file

void factorial (int);

void factorial (int x)
{

    int k, no = 1;Variable Declaration

    for (i=1; k <=n; ++i)
         no *= i;

    printf(“Factorial of %d is %d\n”, n,no);

}

int main(void)
{

    int no = 0;

    printf(“Enter a no\n”);

    scanf(“%d”, &no);
    factorial (no);

    return 0;

}

What is Void?

void anyFunction(void)

The first void is the return type of the function, that is what will be returned when the function is called. Void simply indicates that the function does not return a value.

When we have to return a value we will write:

int add(int a, int b)
{
return (a +  b);
}

void can also be used in the function's parameter list to explicitly specify that we want the function to take no actual parameters when it is called as we can see above, the second void.