ldexp, ldexpf, ldexpl

Multiplies a floating-point number by an integral power of two.

Syntax

``````double ldexp(
double x,
int exp
);
float ldexp(
float x,
int exp
);  // C++ only
long double ldexp(
long double x,
int exp
);  // C++ only
float ldexpf(
float x,
int exp
);
long double ldexpl(
long double x,
int exp
);
``````

Parameters

x
Floating-point value.

exp
Integer exponent.

Return Value

The ldexp functions return the value of x * 2exp if successful. On overflow, and depending on the sign of x, ldexp returns +/- HUGE_VAL; the errno value is set to ERANGE.

Remarks

Because C++ allows overloading, you can call overloads of ldexp that take float or long double types. In a C program, ldexp always takes a double and an int and returns a double.

Requirements

ldexp, ldexpf, ldexpl <math.h> <cmath>

For compatibility information, see Compatibility.

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
``````