ldexp() is a Mathematical Function that returns the resulting floating point value from multiplying the mantissa (x) by 2 raised to the power of exponent(exp).(i.e) It returns the value of "num * 2^exp ". If an overflow occurs "HUGE_VAL" is returned.

    float ldexp( float num, int exp);
    double ldexp( double num, int exp);
    long double ldexp( long double num, int exp);

   #include <stdio.h>
   #include <math.h>
   int main()
     {
        double num, r;
        int exp=4;
        num = 8.0;
        r = ldexp( num, exp);
        printf( "%lf times of 2 to the power 
                  of %d is:: %lf\n", num,exp, r);
        return 0;
     }

    8.000000 times of 2 to the power of 4 is:: 128.000000 

In the above example ldexp() returns the value of "8*2⁴".Thus a floating point number is generated from the mantissa(8.0) and exponent(4).