6.11.78 frexp Function

Gets the fraction and the exponent of a double precision floating-point number.

Include

<math.h>

Prototype

double frexp(double x, int * exp);

Arguments

x

floating-point value for which to return the fraction and exponent

exp

pointer to a stored integer exponent

Return Value

Returns the fraction, exp points to the exponent. If x is 0, the function returns 0 for both the fraction and exponent.

Remarks

The absolute value of the fraction is in the range of 1/2 (inclusive) to 1 (exclusive). No domain or range error will occur.

Example

See the notes at the beginning of this chapter or section for information on using printf() or scanf() (and other functions reading and writing the stdin or stdout streams) in the example code.

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

int main(void)
{
  double x,y;
  int n;

  x = 50.0;
  y = frexp (x, &n);
  printf("For frexp of %f\n the fraction is %f\n ", x, y);
  printf("  and the exponent is %d\n\n", n);

  x = -2.5;
  y = frexp (x, &n);
  printf("For frexp of %f\n the fraction is %f\n ", x, y);
  printf("  and the exponent is %d\n\n", n);

  x = 0.0;
  y = frexp (x, &n);
  printf("For frexp of %f\n the fraction is %f\n ", x, y);
  printf("  and the exponent is %d\n\n", n);
}

Example Output

For frexp of 50.000000
  the fraction is 0.781250
   and the exponent is 6

For frexp of -2.500000
  the fraction is -0.625000
   and the exponent is 2

For frexp of 0.000000
  the fraction is 0.000000
   and the exponent is 0