ilogb(), ilogbf()

Exponent extraction

Synopsis:

#include <math.h>

int ilogb ( double x );

int ilogbf (float x );

libm

The ilogb() and ilogbf() functions compute the integral part of:

log_r |x|

as a signed integral value, for nonzero finite x, where r is the radix of the machine's floating point arithmetic.

The exponent part of x in integer format.

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

int main( void )
{
    printf( "%f\n", ilogb(.5) );
    
    return EXIT_SUCCESS;
}