library function Functions in c programing language types of functions

library function : 

• it is a allready  defined functions is called as pre defined functions 
• easy to use 

example program 

#include<stdio.h>

#include<math.h>

int main()

{

double number;

number=49;

double squareroot =sqrt(number);

printf("The square root of %2f\n is %2f",number,squareroot);

}