---
title: "modf, modff, modfl"
description: "API reference for modf, modff, and modfl; which split a floating-point value into fractional and integer parts."
ms.date: "1/15/2021"
api_name: ["modff", "modf", "modfl", "_o_modf", "_o_modff"]
api_location: ["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", "api-ms-win-crt-private-l1-1-0.dll"]
api_type: ["DLLExport"]
topic_type: ["apiref"]
f1_keywords: ["modff", "_modfl", "modf", "modfl", "math/modf", "math/modff", "math/modfl"]
helpviewer_keywords: ["modf function", "modff function", "modfl function"]
---
# `modf`, `modff`, `modfl`

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

## Syntax

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

```cpp
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`](set-sse2-enable.md) 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, see [Global state in the CRT](../global-state.md).

## Requirements

|Routine|Required header|
|-------------|---------------------|
|**`modf`**, **`modff`**, **`modfl`**|C: `<math.h>`<br /><br /> C++: , `<cmath>` or `<math.h>`|

For more compatibility information, see [Compatibility](../../c-runtime-library/compatibility.md).

## Example

```C
// 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 );
}
```

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

## See also

[Floating-Point Support](../../c-runtime-library/floating-point-support.md)\
[`frexp`](frexp.md)\
[`ldexp`](ldexp.md)