fmod, fmodf, fmodl

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
long double fmodl(
   long double x,
   long double y


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.


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 that take and return float and long double values. In a C program, fmod always takes two double arguments and returns a double.


Function Required header
fmod, fmodf, fmodl <math.h>

For additional compatibility information, see Compatibility.


// 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

See also

Floating-Point Support
ceil, ceilf, ceill
fabs, fabsf, fabsl
floor, floorf, floorl