Types of functions in C

Types of functions in C language

There are two types of functions in C

1. C library functions

C Library functions are inbuilt functions in C programming.

Program for library functions

Square root using sqrt() function in C language

#include <stdio.h>
#include <math.h>
int main()
{
   float num, root;
   printf("Enter a no: ");
   scanf("%f", &num);

   root = sqrt(num);

   printf("Sqroot of %.2f = %.2f", num, root);
   return 0;
}

Enter a no: 12
Sqroot of 12.00 = 3.46

2. C User-defined functions

C allows defining functions according to your need these functions are known as user-defined functions.

For example:

Suppose, you need to create a square and color then you can create two functions

creatsqu() function

color() function

How does the user-defined function work in C?

#include <stdio.h>
void functionName()
{
    ... .. ...
    ... .. ...
}

int main()
{
    ... .. ...
    ... .. ...

    functionName();
    
    ... .. ...
    ... .. ...
}

Program for user-defined function in c language

#include <stdio.h>
int addNo(int p, int q);         // function prototype

int main()
{
    int n1,n2,sum;

    printf("Enters two no: ");
    scanf("%d %d",&n1,&n2);

    sum = addNo(n1, n2);        // function call
    printf("sum = %d",sum);

    return 0;
}

int addNo(int a, int b)         // function definition   
{
    int result;
    result = p+q;
    return result;                  // return statement
}

Enters two no: 10

20

sum = 30