Java Program to Reverse a Number

WAP to reverse a number in Java

Logical Steps:

To reverse a number, follow these steps:
1. Take one number.
2. Use two variables: one to store the reversed number (reversedNumber) and another to hold the remainder (remainder).
3. Use a Loop to Reverse the Number:
  - Use a while loop until the number becomes 0.
  - In each iteration:
    - Extract the last digit of the number using the modulus operator (number % 10).
    - Add this digit to the reversed number after multiplying the existing reversed number by 10.
    - Remove the last digit from the number using integer division (number / 10).
4. After the loop ends, display the reversed number.

Programs:

Below is the simple program:

public class ReverseNumber
{
    public static void main(String[] args)
    {
        int number = 12345;

        int reversedNumber = 0;

        // Reverse the number using a while loop
        while (number != 0)
        {
            int remainder = number % 10;  // Get the last digit
            reversedNumber = reversedNumber * 10 + remainder;  // Build the reversed number
            number = number / 10;  // Remove the last digit
        }

        // Display the reversed number
        System.out.println("Reversed Number: " + reversedNumber);
    }
}

Output:

Reversed Number: 54321

Below is the program by taking user input:

import java.util.Scanner;

public class ReverseNumber
{
    public static void main(String[] args)
    {
        Scanner scanner = new Scanner(System.in);

        // Take user input
        System.out.print("Enter a number to reverse: ");
        int number = scanner.nextInt();

        int reversedNumber = 0;

        // Reverse the number using a while loop
        while (number != 0)
        {
            int remainder = number % 10;  // Get the last digit
            reversedNumber = reversedNumber * 10 + remainder;  // Build the reversed number
            number = number / 10;  // Remove the last digit
        }

        // Display the reversed number
        System.out.println("Reversed Number: " + reversedNumber);

        // Close the scanner
        scanner.close();
    }
}

Output:

Enter a number to reverse: 135897
Reversed Number: 798531

Program Explanation:

Input and Variables:
- The program takes an integer input from the user.
- Two variables are used:
  - reversedNumber to store the reversed value (initially set to 0).
  - remainder to hold the last digit of the number in each iteration.
Reversing Logic:
- The while loop continues as long as the number is not 0.
- In each iteration:
  - The last digit of the number is obtained using number % 10.
  - This digit is added to reversedNumber after shifting its existing digits to the left by multiplying by 10.
  - The last digit is then removed from the original number using number / 10.
Display the Result:
- Once the loop ends, the reversed number is printed.
Close Scanner:
- The scanner.close() method is used to close the input stream and release resources.

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WAP to reverse a number in Java

Logical Steps:

Programs:

Output:

Output:

Program Explanation:

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