Gets the mantissa and exponent of a floating-point number.
double frexp( double x, int *expptr );
| Function | Required Header | Compatibility |
| frexp | <math.h> | ANSI, Win 95, Win NT |
For additional compatibility information, see Compatibility in the Introduction.
Libraries
| LIBC.LIB | Single thread static library, retail version |
| LIBCMT.LIB | Multithread static library, retail version |
| MSVCRT.LIB | Import library for MSVCRT.DLL, retail version |
Return Value
frexp returns the mantissa. If x is 0, the function returns 0 for both the mantissa and the exponent. There is no error return.
Parameters
x
Floating-point value
expptr
Pointer to stored integer exponent
Remarks
The frexp function breaks down the floating-point value (x) into a mantissa (m) and an exponent (n), such that the absolute value of m is greater than or equal to 0.5 and less than 1.0, and x = m*2n. The integer exponent n is stored at the location pointed to by expptr.
Example
/* FREXP.C: This program calculates frexp( 16.4, &n )
* then displays y and n.
*/
#include <math.h>
#include <stdio.h>
void main( void )
{
double x, y;
int n;
x = 16.4;
y = frexp( x, &n );
printf( "frexp( %f, &n ) = %f, n = %d\n", x, y, n );
}
Output
frexp( 16.400000, &n ) = 0.512500, n = 5