Question

A palindrome is a word or phrase that reads the same forward and backward, ignoring blanks and considering uppercase and lowercase versions of the same letter to be equal. For example, the following are palindromes:
• warts n straw
• radar
• Able was I ere I saw Elba
• tacocat
Write a program that will accept a sequence of characters terminated by a period and will decide whether the string—without the period—is a palindrome. You may assume that the input contains only letters and blanks and is at most 80 characters long. Include a loop that allows the user to check additional strings until she or he requests that the program end. (Hint: Define a static method called isPalindrome that begins as follows.)
/**
Precondition: The array a contains letters and blanks in positions a[0] through a[used − 1]. Returns true if the
string is a palindrome and false otherwise.

*/

public static boolean isPalindrome(char[] a, int used)

Your program should read the input characters into an array whose base type is char and then call the preceding method. The int variable used keeps track of how much of the array is used as described in the section entitled “Partially Filled Arrays.”

Answer 1

CODE IN JAVA:

Palindrome.java file:

import java.util.Scanner ;
public class Palindrome {
   public static boolean isPalindrome(char a[], int used) {
       for(int i = 0 ; i < used/2 ; i++) {
           if(a[i] != a[used - i - 1])
               return false;
       }
       return true;
   }
   public static void main(String[] args) {
      
       Scanner sc = new Scanner(System.in);
       System.out.print("Enter the string terminated with dot : ");
       String inputStr = sc.nextLine();
       inputStr = inputStr.toLowerCase();
       char arr[] = inputStr.toCharArray();
       int n = 0;
       for(int i = 0 ; i < arr.length; i++) {
           if(arr[i] == '.') {
               n = i ;
               break;
           }
       }
       if(n==0)
           n = arr.length;
       boolean result = isPalindrome(arr, n);
       if(result)
           System.out.println("It is palindrome...");
       else
           System.out.println("It is not a palindrome...");

   }

}

OUTPUT: