In this C++ tutorial, you will learn how to find the product of x, and 2 raised to the power e, using ldexp() function of cmath, with syntax and examples.

C++ ldexp()

C++ ldexp() returns product of x, and 2 raised to the power e, where x and e are given as arguments.

ldexp(x, exp) = x * 2^exp

Syntax

The syntax of C++ ldexp() is

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ldexp(x, exp)

where

ParameterDescription
xA double, float, long double, or any integral type value.
expAn integer value.

Returns

The return value depends on the type of value passed for parameter x.

The return value of ldexp(x) is

  • double if x is double or integral type.
  • float if x is float.
  • long double if x is long double.

The synopsis of ldexp() function is

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double ldexp (double x, int exp);
float ldexp (float x, int exp);
long double ldexp (long double x, int exp);
double ldexp (T x, int exp);// for integral type argument values

ldexp() is a function of cmath library. Include cmath library in the program, if using ldexp() function.

Example

In this example, we read two values from user into variable x and variable exp, and find the product of x and 2 raised to the power exp, using ldexp() function.

C++ Program

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#include <iostream>
#include<cmath>
using namespace std;

int main() {
    double x;
    int exp;
    cout << "Enter a number : ";
    cin >> x;
    cout << "Enter exponent : ";
    cin >> exp;
    
    double result = ldexp(x, exp);
    cout << "ldexp(" << x << ", " << exp << ") : "
        << result << endl;
}

Output

Enter a number : 5
Enter exponent : 2
ldexp(5, 2) : 20
Program ended with exit code: 0
Enter a number : 3
Enter exponent : 4
ldexp(3, 4) : 48
Program ended with exit code: 0

Conclusion

In this C++ Tutorial, we learned the syntax of C++ ldexp(), and how to use this function to find the product of x and 2 raised to the power exp, with the help of examples.