Java Program to Find Nth Power of a Number by Using Recursion

In the previous article, we have discussed about Java Program to Reverse a String by Using Recursion

In this program we are going to see how to find Nth power of a number using Recursion in Java programming language.

Java Program to Find Nth Power of a Number by Using Recursion

Let’s start with an example to understand it more clearly.

Assume  the base i.e b = 2
Power to the base i.e p = 4
Result = b^p = 2^4 = 2*2*2*2 = 16

Now let’s see different ways to find Nth power of a number by using Recursion.

By Using Static Input and Recursion
By Using User Input and Recursion

Method-1: Java Program to Find Nth Power of a Number By Using Static Input and Recursion

Approach:

Declare an integer variable say ‘base’ and initialize it.
Declare an integer variable say ‘power’ and initialize it.
Call a user defined method findPower() method and pass the Integers ‘base’, ‘power’ as parameters.
Inside the user defined method we will check if the base is 0 then we will return the vale as 1
Else if the base > 0 then we will recursively call findPower() method to get the result “b*findPower(b,p-1)” and return the value to the main() method.
Else if the base < 0 then we will recursively call findPower() method to get the result “1/findPower(b, -p)” and return the value to the main() method.
Now the value of the user defined method findPower() is stored in a double variable say ‘value’ inside the main() method.
Print the result.

Program:

public class Main 
{
    public static void main(String[] args)
    {
        //declare an integer variable ‘base’ and initialize it 
        int base = 2;
        //declare an integer variable ‘power’ and initialize it 
        int power = 4;
        //calling findPower() method and pass the Integers ‘base’, ‘power’ as parameters
        double value = findPower(base, power);
        // print the result
        System.out.println("The value of base "+base+" and power "+power+" is: "+value);
    }

    //recursive function to find the value of power of the base        
    static double findPower(int b, int p)
    {
        // if the power is 0 then return 1
        if(p == 0)
            return 1;
        // if the power is greater than 0 then recursively call findPower() method and return the value
        else if (p>0)
            return b*findPower(b,p-1);
        // if the power is less than 0 then recursively call findPower() method and return the value
        else
            return 1/findPower(b, -p);
    }
}

Output:

The value of base 2 and power 4 is: 16.0

Method-2: Java Program to Find Nth Power of a Number By Using User Input and Recursion

Approach:

Declare an integer variable say ‘base’
Declare an integer variable say ‘power’
Prompt the user to enter the values for the ‘base’ and ‘power’ respectively.
Call a user defined method findPower() method and pass the Integers ‘base’, ‘power’ as parameters.
Inside the user defined method we will check if the base is 0 then we will return the vale as 1.
Else if the base > 0 then we will recursively call findPower() method to get the result “b*findPower(b,p-1)” and return the value to the main() method.
Else if the base < 0 then we will recursively call findPower() method to get the result “1/findPower(b, -p)” and return the value to the main() method.
Now the value of the user defined method findPower() is stored in a double variable say ‘value’ inside the main() method.
Print the result.

Program:

import java.util.*;
import java.io.*;
public class Main 
{
    public static void main(String[] args)
    {
        // create a scanner class
        Scanner sc = new Scanner(System.in);
        System.out.println("Enter the base of the number: ");
        //declare an integer variable ‘base’ and initialize it by user input using scanner class.
        int base = sc.nextInt();
        System.out.println("Enter the power of the number: ");
        //declare an integer variable ‘power’ and initialize it by user input using scanner class.
        int power = sc.nextInt();
        //calling findPower() method and pass the Integers ‘base’, ‘power’ as parameters
        double value = findPower(base, power);
        // print the result
        System.out.println("The value of base "+base+" and power "+power+" is: "+value);
    }

    //recursive function to find the value of power of the base        
    static double findPower(int b, int p)
    {
        // if the power is 0 then return 1
        if(p == 0)
            return 1;
        // if the power is greater than 0 then recursively call findPower() method and return the value
        else if (p>0)
    		return b*findPower(b,p-1);
        // if the power is less than 0 then recursively call findPower() method and return the value
        else
            return 1/findPower(b, -p);
    }
}

Output:

Enter the base of the number: 
2
Enter the power of the number: 
-4
The value of base 2 and power -4 is: 0.0625

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