Java Program to Calculate the Power of a Number

In this program, you'll learn to calculate the power of a number with and without using pow() function.

Example 1: Calculate power of a number using a while loop

public class Power {

    public static void main(String[] args) {

        int base = 3, exponent = 4;

        long result = 1;

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

        System.out.println("Answer = " + result);
    }
}

When you run the program, the output will be:

Answer = 81

In this program, base and exponent are assigned values 3 and 4 respectively.

Using the while loop, we keep on multiplying result by base until exponent becomes zero.

In this case, we multiply result by base 4 times in total, so result = 1 * 3 * 3 * 3 * 3 = 81.


Example 2: Calculate power of a number using a for loop

public class Power {

    public static void main(String[] args) {

        int base = 3, exponent = 4;

        long result = 1;

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

        System.out.println("Answer = " + result);
    }
}

When you run the program, the output will be:

Answer = 81

Here, instead of using a while loop, we've used a for loop.

After each iteration, exponent is decremented by 1, and result is multiplied by base exponent number of times.

Both programs above doesn't work if you have a negative exponent. For that, you need to use pow() function in Java standard library.


Example 3: Calculate the power of a number using pow() function

public class Power {

    public static void main(String[] args) {

        int base = 3, exponent = -4;
        double result = Math.pow(base, exponent);

        System.out.println("Answer = " + result);
    }
}

When you run the program, the output will be:

Answer = 0.012345679012345678

In this program, we use Java's Math.pow() function to calculate the power of the given base.