modf(), modff(), modfl()

Break a number into integral and fractional parts

Synopsis:

#include <math.h>

double modf( double value,
             double* iptr );

float modff( float value,
             float* iptr );

long double modfl( long double value,
                   long double* iptr );

Arguments:

value
The value that you want to break into parts.
iptr
A pointer to a location where the function can store the integral part of the number.

Library:

libm

Use the -l m option to qcc to link against this library.

Description:

The modf(), modff(), and modfl() functions break the given value into integral and fractional parts, each of which has the same sign as the argument. They store the integral part in the object pointed to by iptr.

To check for error situations, use feclearexcept() and fetestexcept():

Returns:

The signed fractional part of value. If x is NaN, NaN is returned, and *iptr is set to NaN. If x is ±Inf, ±0 is returned, and *iptr is set to ±Inf.

Examples:

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

int main( void )
{
    double integral_value, fractional_part;

    fractional_part = modf( 4.5, &integral_value );
    printf( "%f %f\n", fractional_part, integral_value );
    
    fractional_part = modf( -4.5, &integral_value );
    printf( "%f %f\n", fractional_part, integral_value );
    
    return EXIT_SUCCESS;
}

produces the output:

0.500000 4.000000
-0.500000 -4.000000

Classification:

ANSI, POSIX 1003.1

Safety:  
Cancellation point No
Interrupt handler No
Signal handler No
Thread Yes