In this C++ tutorial, you will learn how to compute the value of x scaled by FLT_RADIX to the power exp. using scalbn() function of cmath, with syntax and examples.

## C++ scalbn()

C++ scalbn(x, exp) computes the value of x scaled by FLT_RADIX to the power exp.

`scalbn(x, exp) = x * FLT_RADIX^exp`

## Syntax

The syntax of C++ scalbn() is

`scalbn(x, exp)`

where

Returns

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

The return value of scalbn(x, exp) is

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

The synopsis of scalbn() function is

```double scalbn(double x, int exp);
float scalbn(float x, int exp);
long double scalbn(long double x, int exp);
double scalbn(Type1 x, int exp); // for integral types```

scalbn() is a function of cmath library. Include cmath library at the start of program, if using scalbn() function.

## Example

In this example, we read two values from user into variables x and exp, and compute result of scalbn(x, exp).

C++ Program

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

int main() {
double x;
int exp;
cout << "Enter x   : ";
cin >> x;
cout << "Enter exp : ";
cin >> exp;

double result = scalbn(x, exp);
cout << "scalbn(" << x << ") : " << result << endl;
}```

Output

```Enter x   : 5
Enter exp : 3
scalbn(5) : 40
Program ended with exit code: 0```
```Enter x   : 8
Enter exp : 1
scalbn(8) : 16
Program ended with exit code: 0```

If `x` is NaN, scalbn() returns NaN.

```Enter x   : nan
Enter exp : 3
scalbn(nan) : nan
Program ended with exit code: 0```

## Conclusion

In this C++ Tutorial, we learned the syntax of C++ scalbn(), and how to use this function, with the help of examples.