Header File 

math.h  

Category 

Math Routines 

Prototype 

double ldexp(double x, int exp); 

long double ldexpl(long double x, int exp); 

Description 

Calculates x * 2^exp. 

lexpl is the long double version; it takes a long double argument for x and returns a long double result. 

Return Value 

On success, ldexp (or ldexpl) returns the value it calculated, x * 2^exp. Error handling for these routines can be modified through the functions _matherr and _matherrl. 

Example  

#include <stdio.h>
#include <math.h>
int main(void)
{
    double value;
    double x = 2;
    /* ldexp raises 2 by a power of 3
       then multiplies the result by 2   */
    value = ldexp(x,3);
    printf("The ldexp value is: %lf\n", value);
    return 0;
}

Portability