frexp() -- General Function (libc)

Separate fraction and exponent
#include <math.h>
double frexp(real, ep)
double real; int *ep;

frexp() breaks  double-precision floating  point numbers into  fraction and
exponent.  It  returns the fraction m  of its real argument,  such that 0.5
<= m  < 1 or  m=0, and stores  the binary exponent e  in the location
pointed to by ep. These numbers satisfy the equation real = m * 2e.

Example

This example prompts  for a number, then uses frexp()  to break it into its
fraction and exponent.

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

main()
{
    double real, fraction;
    int ep;

    char string[64];

    for (;;) {
        printf("Enter number: ");
        if (gets(string) == NULL)
            break;

        fraction = frexp(real, &ep);
        printf("%lf is the fraction of %lf\n",
            fraction, real);
        printf("%d is the binary exponent of %lf\n",
            ep, real);
    }
}

See Also

atof(),
ceil(),
fabs(),
floor(),
ldexp(),
libc,
modf()
ANSI Standard, §7.5.4.3
POSIX Standard, §8.1

© 2012 by Stephen A. Ness