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Check If a String is a Palindrome Using Recursion in C#

In this C# program, the goal is to write a recursive function that checks if a given string is a palindrome (symmetric). A palindrome is a word, phrase, or sequence that reads the same backward as forward. For example, the word "RADAR" is a palindrome because it remains the same when reversed. The program uses recursion to compare the characters from both ends of the string, ensuring they are the same as it reduces the problem size with each recursive call.



Group

Functions in C#

Objective

1. Implement a recursive function to check if a string is symmetric (a palindrome).
2. The function should compare the first and last characters of the string.
3. If they match, recursively check the inner portion of the string by calling the function on a substring.
4. If the characters do not match, return false.
5. The base case for the recursion should be when the string has a length of 1 or 0, which is trivially a palindrome.

Write a C# recursive function to say whether a string is symmetric (a palindrome). For example, "RADAR" is a palindrome.

Example C# Exercise

 Copy C# Code 
using System;

class Program
{
    // Function to check if a string is a palindrome using recursion
    static bool IsPalindrome(string str)
    {
        // Base case: If the string has 0 or 1 character, it's a palindrome
        if (str.Length <= 1)
        {
            return true;
        }

        // Check if the first and last characters are the same
        if (str[0] != str[str.Length - 1])
        {
            return false; // Return false if characters don't match
        }

        // Recursively check the inner substring
        return IsPalindrome(str.Substring(1, str.Length - 2));
    }

    static void Main()
    {
        // Test the IsPalindrome function with the string "RADAR"
        string testString = "RADAR";
        if (IsPalindrome(testString))
        {
            Console.WriteLine($"{testString} is a palindrome.");
        }
        else
        {
            Console.WriteLine($"{testString} is not a palindrome.");
        }

        // Test the IsPalindrome function with a string that is not a palindrome
        testString = "HELLO";
        if (IsPalindrome(testString))
        {
            Console.WriteLine($"{testString} is a palindrome.");
        }
        else
        {
            Console.WriteLine($"{testString} is not a palindrome.");
        }
    }
}

 Output

RADAR is a palindrome.
HELLO is not a palindrome.

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More C# Practice Exercises of Functions in C#

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