C++ Program to Calculate Power of a Number

In the following example of C++ program Calculate power to a number manually, and by using pow() function.

This program takes two numbers from the user (a base number and an exponent) and calculates the power.

Power of a number = base^exponent

Compute Power Manually :

Program :

#include <iostream>
using namespace std;

int main() 
{
    int exponent;
    float base, result = 1;

    cout << "Enter base and exponent respectively:  ";
    cin >> base >> exponent;

    cout << base << "^" << exponent << " = ";

    while (exponent != 0) {
        result *= base;
        --exponent;
    }

    cout << result;
    
    return 0;
}

Output :

Enter base and exponent respectively:  2.7
3
2.7^3 = 19.683

As we know, the power of a number is the number multiplied by itself repeatedly. For example,

53 = 5 x 5 x 5 = 125

Here, 5 is the base and 3 is the exponent.

In this program, we have calculated the power of a number using a while loop.

while (exponent != 0) {
    result *= base;
    --exponent;
}

Remember that we have already initialized result as 1 during the beginning of the program.

Let us see how this while loop works if base == 5 and exponent == 3.

Iteration	result *= base	exponent	exponent != 0	Execute Loop?
1st	`5`	`3`	`true`	Yes
2nd	`25`	`2`	`true`	Yes
3rd	`125`	`1`	`true`	Yes
4th	`625`	`0`	`false`	No

However, the above technique works only if the exponent is a positive integer.

If you need to find the power of a number with any real number as an exponent, you can use pow() function.

Compute power using pow() Function :

Program :

#include <iostream>
#include <cmath>

using namespace std;

int main() 
{
    float base, exponent, result;

    cout << "Enter base and exponent respectively:  ";
    cin >> base >> exponent;

    result = pow(base, exponent);

    cout << base << "^" << exponent << " = " << result;
    
    return 0;
}

Output :

Enter base and exponent respectively:  2.5
4.1
2.5^4.1 = 42.8109

* In this program, we have used the pow() function to calculate the power of a number.

* Notice that we have included the cmath header file in order to use the pow() function.

* We take the base and exponent from the user.

* We then use the pow() function to calculate the power. The first argument is the base, and the second argument is the exponent.

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