Header File 

math.h  

Category 

Math Routines 

Prototype 

double pow(double x, double y); 

long double powl(long double x, long double y); 

Description 

Calculates x to the power of y. 

powl is the long double version; it takes long double arguments and returns a long double result. 

Return Value 

On success, pow and powl return the value calculated of x to the power of y. 

Sometimes the arguments passed to these functions produce results that overflow or are incalculable. When the correct value would overflow, the functions return the value HUGE_VAL (pow) or _LHUGE_VAL (powl). Results of excessively large magnitude can cause the global variable errno to be set to

If the argument x passed to pow or powl is real and less than 0, and y is not a whole number, or if x is 0 and y is less than 0, or you call pow(0,0), the global variable errno is set to

Error handling for these functions can be modified through the functions _matherr and _matherrl. 

Example  

#include <math.h>
#include <stdio.h>
int main(void)
{
  double x = 2.0, y = 3.0;
  printf("%lf raised to %lf is %lf\n", x, y, pow(x, y));
  return 0;
}

Portability