Header File 

math.h  

Category 

Math Routines 

Prototype 

double sqrt(double x); 

long double sqrtl(long double x); 

Description 

Calculates the positive square root. 

sqrt calculates the positive square root of the argument x. 

sqrtl is the long double version; it takes a long double argument and returns a long double result. Error handling for these functions can be modified through the functions _matherr and _matherrl. 

Return Value 

On success, sqrt and sqrtl return the value calculated, the square root of x. If x is real and positive, the result is positive. If x is real and negative, the global variable errno is set to

Example

#include <math.h>
#include <stdio.h>
int main(void)
{
   double x = 4.0, result;
   result = sqrt(x);
   printf("The square root of %lf is %lf\n", x, result);
   return 0;
}

Portability