ldexp
Visual Studio .NET 2003
Computes a real number from the mantissa and exponent.
double ldexp( double x, int exp ); float ldexp( float x, int exp ); // C++ only long double ldexp( long double x, int exp ); // C++ only
Parameters
- x
- Floating-point value.
- exp
- Integer exponent.
Return Value
The ldexp function returns the value of x * 2exp if successful. On overflow (depending on the sign of x), ldexp returns +/– HUGE_VAL; the errno variable is set to ERANGE.
See _doserrno, errno, _sys_errlist, and _sys_nerr for more information on this, and other, return codes.
Remarks
C++ allows overloading, so you can call overloads of ldexp. In a C program, ldexp always takes a double and an int and returns a double.
Requirements
| Routine | Required header | Compatibility |
|---|---|---|
| ldexp | <math.h> | ANSI, Win 98, Win Me, Win NT, Win 2000, Win XP |
For additional compatibility information, see Compatibility in the Introduction.
Libraries
All versions of the C run-time libraries.
Example
// crt_ldexp.c
#include <math.h>
#include <stdio.h>
int main( void )
{
double x = 4.0, y;
int p = 3;
y = ldexp( x, p );
printf( "%2.1f times two to the power of %d is %2.1f\n", x, p, y );
}
Output
4.0 times two to the power of 3 is 32.0
See Also
Floating-Point Support | frexp | modf | Run-Time Routines and .NET Framework Equivalents
