modf-modff-modfl.md

title	description	ms.date	api_name	api_location	api_type	topic_type	f1_keywords	helpviewer_keywords
modf, modff, modfl	API reference for modf, modff, and modfl; which split a floating-point value into fractional and integer parts.	1/15/2021	modff modf modfl _o_modf _o_modff	msvcrt.dll msvcr80.dll msvcr90.dll msvcr100.dll msvcr100_clr0400.dll msvcr110.dll msvcr110_clr0400.dll msvcr120.dll msvcr120_clr0400.dll ucrtbase.dll api-ms-win-crt-math-l1-1-0.dll	DLLExport	apiref	modff _modfl modf modfl math/modf math/modff math/modfl	modf function modff function modfl function

modf, modff, modfl

Splits a floating-point value into fractional and integer parts.

Syntax

double modf( double x, double * intptr );
float modff( float x, float * intptr );
long double modfl( long double x, long double * intptr );

float modf( float x, float * intptr );  // C++ only
long double modf( long double x, long double * intptr );  // C++ only

Parameters

x
Floating-point value.

intptr
Pointer to stored integer portion.

Return value

This function returns the signed fractional portion of x. There's no error return.

Remarks

The modf functions break down the floating-point value x into fractional and integer parts, each of which has the same sign as x. The signed fractional portion of x is returned. The integer portion is stored as a floating-point value at intptr.

modf has an implementation that uses Streaming SIMD Extensions 2 (SSE2). See _set_SSE2_enable for information and restrictions on using the SSE2 implementation.

C++ allows overloading, so you can call overloads of modf that take and return float or long double parameters. In a C program, modf always takes two double values and returns a double value.

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

Requirements

Routine	Required header
modf, modff, modfl	C: <math.h> C++: , <cmath> or <math.h>

For more compatibility information, see Compatibility.

Example

// crt_modf.c

#include <math.h>
#include <stdio.h>

int main( void )
{
   double x, y, n;

   x = -14.87654321;      /* Divide x into its fractional */
   y = modf( x, &n );     /* and integer parts            */

   printf( "For %f, the fraction is %f and the integer is %.f\n",
           x, y, n );
}

For -14.876543, the fraction is -0.876543 and the integer is -14

See also

Math and floating-point support
frexp
ldexp