WAP to check whether a number is Palindrome in Java
What is Palindrome Number ?
- A palindrome number is a number that reads the same forward and backward.
- For example, 121, 545 and 1331 are palindrome numbers.
Logical Steps:
- Store the original number in a temporary variable.
- Reverse the digits of the number using a loop.
- Compare the reversed number with the original number.
- If they are the same, it’s a palindrome; otherwise, it’s not.
Programs:
-
Below is the simple program:
public class PalindromeNumber { public static void main(String[] args) { int no = 52325; // Number to check for palindrome int originalNumber = no; int reversedNumber = 0; while (no != 0) { int digit = no % 10; // Get the last digit reversedNumber = reversedNumber * 10 + digit; // Build the reversed number no = no / 10; // Remove the last digit } // Check if the original number and reversed number are the same if (originalNumber == reversedNumber) { System.out.println(originalNumber + " is a Palindrome number."); } else { System.out.println(originalNumber + " is not a Palindrome number."); } } }Output:
52325 is a Palindrome number.
-
Below is the program by taking user input:
import java.util.Scanner; public class PalindromeNumber { public static void main(String[] args) { Scanner scanner = new Scanner(System.in); System.out.print("Enter the number: "); int no = scanner.nextInt(); // Number to check for palindrome int originalNumber = no; int reversedNumber = 0; while (no != 0) { int digit = no % 10; // Get the last digit reversedNumber = reversedNumber * 10 + digit; // Build the reversed number no = no / 10; // Remove the last digit } // Check if the original number and reversed number are the same if (originalNumber == reversedNumber) { System.out.println(originalNumber + " is a Palindrome number."); } else { System.out.println(originalNumber + " is not a Palindrome number."); } } }Output:
Enter the number: 121 121 is a Palindrome number.
Program Explanation:
-
Initialization and Variables:
-
A variable
nois initialized with the number to check (e.g., 121). -
Two more variables:
-
originalNumberstores the original number for later comparison. -
reversedNumberis initialized to 0 to build the reversed number.
-
-
A variable
-
Reversing the Number:
-
A
whileloop runs untilnobecomes 0:-
Extract the last digit using
no % 10. -
Add this digit to
reversedNumberafter shifting it by one place (multiply by 10). -
Remove the last digit from
nousingno / 10.
-
Extract the last digit using
-
A
-
Comparison:
-
After the loop, compare
originalNumberwithreversedNumber- If they are the same, the number is a Palindrome.
- Otherwise, it's not a Palindrome.
-
After the loop, compare
-
Output:
- Print whether the original number is a palindrome or not.
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