Function Palindrome, Recursive - C# Programming Exercise

In this exercise in C#, you will need to create a recursive function to check if a string is symmetric (a palindrome). A palindrome is a word, number, phrase, or other sequence of characters that reads the same forward and backward. For example, "RADAR" is a palindrome. This exercise in C# will help you enhance your skills with recursive functions and string manipulation. In this case, recursion will allow you to compare characters from both ends of the string, gradually reducing the size of the problem until it determines whether the string is a palindrome or not. In this exercise, you will learn how to apply recursion in C# to solve problems elegantly and efficiently.

By completing this exercise, you will be able to implement recursive functions that handle strings and other data structures in your programs, thereby gaining a deeper understanding of how to work with recursion in C#.

Exercise

Function Palindrome, Recursive

Objective

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

Example C# Exercise

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// Import the System namespace to use basic classes like Console
using System;

class Program
{
    // Recursive function to check if a string is a palindrome (symmetric)
    public static bool Palindrome(string str)
    {
        // Convert the string to uppercase to make the comparison case-insensitive
        str = str.ToUpper();

// Base case: if the string has one or zero characters, it's a palindrome
        if (str.Length <= 1)
        {
            return true;
        }

// Compare the first and last characters
        if (str[0] != str[str.Length - 1])
        {
            return false; // If they are not equal, it's not a palindrome
        }

// Recur with the substring excluding the first and last characters
        return Palindrome(str.Substring(1, str.Length - 2));
    }

// Main function to test the Palindrome function
    public static void Main()
    {
        // Test case 1: "RADAR"
        string testString1 = "RADAR";
        Console.WriteLine($"Is \"{testString1}\" a palindrome? {Palindrome(testString1)}");

// Test case 2: "HELLO"
        string testString2 = "HELLO";
        Console.WriteLine($"Is \"{testString2}\" a palindrome? {Palindrome(testString2)}");

// Test case 3: "madam"
        string testString3 = "madam";
        Console.WriteLine($"Is \"{testString3}\" a palindrome? {Palindrome(testString3)}");
    }
}

// Import the System namespace to use basic classes like Console
using System;

class Program
{
    // Recursive function to check if a string is a palindrome (symmetric)
    public static bool Palindrome(string str)
    {
        // Convert the string to uppercase to make the comparison case-insensitive
        str = str.ToUpper();

        // Base case: if the string has one or zero characters, it's a palindrome
        if (str.Length <= 1)
        {
            return true;
        }

        // Compare the first and last characters
        if (str[0] != str[str.Length - 1])
        {
            return false; // If they are not equal, it's not a palindrome
        }

        // Recur with the substring excluding the first and last characters
        return Palindrome(str.Substring(1, str.Length - 2));
    }

    // Main function to test the Palindrome function
    public static void Main()
    {
        // Test case 1: "RADAR"
        string testString1 = "RADAR";
        Console.WriteLine($"Is \"{testString1}\" a palindrome? {Palindrome(testString1)}");

        // Test case 2: "HELLO"
        string testString2 = "HELLO";
        Console.WriteLine($"Is \"{testString2}\" a palindrome? {Palindrome(testString2)}");

        // Test case 3: "madam"
        string testString3 = "madam";
        Console.WriteLine($"Is \"{testString3}\" a palindrome? {Palindrome(testString3)}");
    }
}

Output

Is "RADAR" a palindrome? True
Is "HELLO" a palindrome? False
Is "madam" a palindrome? True

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Function Palindrome, Recursive - C# Programming Exercise

Category

Functions

Exercise