Calculates the floating-point remainder.
double fmod( 
   double x,
   double y 
);
float fmod(
   float x,
   float y 
);  // C++ only
long double fmod(
   long double x,
   long double y
);  // C++ only
float fmodf( 
   float x,
   float y 
);
Parameters
- x, y
 Floating-point values.
Return Value
fmod returns the floating-point remainder of x / y. If the value of y is 0.0, fmod returns a quiet NaN. For information about representation of a quiet NaN by the printf family, see printf.
Remarks
The fmod function calculates the floating-point remainder f of x / y such that x = i * y + f, where i is an integer, f has the same sign as x, and the absolute value of f is less than the absolute value of y.
C++ allows overloading, so you can call overloads of fmod. In a C program, fmod always takes two doubles and returns a double.
Requirements
| Function | Required header | 
|---|---|
| fmod, fmodf | <math.h> | 
For additional compatibility information, see Compatibility in the Introduction.
Example
// crt_fmod.c
// This program displays a floating-point remainder.
#include <math.h>
#include <stdio.h>
int main( void )
{
   double w = -10.0, x = 3.0, z;
   z = fmod( w, x );
   printf( "The remainder of %.2f / %.2f is %f\n", w, x, z );
}
The remainder of -10.00 / 3.00 is -1.000000