A palindrome is a string that can be read from right to left, and yet still
remains the same as the string read left to right. For example, ‘racecar’ and
‘level’ are both palindromes because if you read the strings from right to left
they are equivalent to the strings read left to right.
So, how shoud we approach writing a function that, given a string as input,
determines whether or not that string is a palindrome? What is the defining
feature of a palindrome? That, when read from right to left it is the same as
the string read left to right.
What if we just create a temporary string where we store the string read from
right to left, and then compare that to the original string. If they are the
same, then it’s a palindrome, if different then the string is NOT a palindrome.
Sounds simple enough, here’s what the pseudocode would look like:
example: madam
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import java.util.*; class Palindrometest{ public static void main(String args[]){ String orig, rev=""; Scanner in = new Scanner(System.in); System.out.println("Enter a string to check if it is a palindrome"); orig = in.nextLine(); int length = orig.length(); for ( int i = length - 1 ; i >= 0 ; i-- ) rev = rev + orig.charAt(i); if (orig.equals(rev)) System.out.println("Entered string is a palindrome."); else System.out.println("Entered string is not a palindrome."); }} |