Was this page helpful?
Your feedback about this content is important. Let us know what you think.
Additional feedback?
1500 characters remaining
modf, modff
Collapse the table of content
Expand the table of content

modf, modff

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

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


Floating-point value.


Pointer to stored integer portion.

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

The modf function breaks 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. In a C program, modf always takes two double values and returns a double value.


Required header

modf, modff


For additional compatibility information, see Compatibility in the Introduction.


All versions of the C run-time libraries.

// 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
© 2015 Microsoft