Header File 

math.h  

Category 

Math Routines 

Prototype 

double fmod(double x, double y); 

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

Description 

Calculates x modulo y, the remainder of x/y.  

fmod calculates x modulo y (the remainder f, where x = ay + f for some integer a, and 0 < f < y).  

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

Return Value 

fmod and fmodl return the remainder f where x = ay + f (as described above). When y = 0, fmod and fmodl return 0. 

Example  

#include <stdio.h>
#include <math.h>
int main(void)
{
   double x = 5.0, y = 2.0;
   double result;
   result = fmod(x,y);
   printf("The remainder of (%lf / %lf) is %lf\n", x, y, result);
   return 0;
}

Portability