`remainder`, `remainderf`, `remainderl`

Article
2022-12-02

Computes the remainder of the quotient of two floating-point values, rounded to the nearest integral value.

Syntax

double remainder( double x, double y );
float remainderf( float x, float y );
long double remainderl( long double x, long double y );
#define remainder(X, Y) // Requires C11 or higher

float remainder( float x, float y ); /* C++ only */
long double remainder( long double x, long double y ); /* C++ only */

Parameters

x
The numerator.

y
The denominator.

Return value

The floating-point remainder of x / y. If the value of y is 0.0, remainder returns a quiet NaN. For information about the representation of a quiet NaN by the printf family, see printf, _printf_l, wprintf, _wprintf_l.

Remarks

The remainder functions calculate the floating-point remainder r of x / y such that x = n * y + r, where n is the integer nearest in value to x / y and n is even whenever |n - x / y| = 1/2. When r = 0, r has the same sign as x.

Because C++ allows overloading, you can call overloads of remainder that take and return float or long double values. In a C program, unless you're using the <tgmath.h> macro to call this function, remainder always takes two double arguments and returns a double.

If you use the <tgmath.h> remainder() macro, the type of the argument determines which version of the function is selected. See Type-generic math for details.

By default, this function's global state is scoped to the application. To change this behavior, see Global state in the CRT.

Requirements

Function	Required header (C)	Required header (C++)
`remainder`, `remainderf`, `remainderl`	<math.h>	<cmath> or <math.h>
`remainder` macro	<tgmath.h>

For compatibility information, see Compatibility.

Example

// crt_remainder.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 = remainder(w, x);
   printf("The remainder of %.2f / %.2f is %f\n", w, x, z);
}

The remainder of -10.00 / 3.00 is -1.000000

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