C#: Exchange the first and last characters in a given string and return the new string

Last update on June 25 2025 13:03:14 (UTC/GMT +8 hours)

Exchange First and Last Characters

Write a C# Sharp program to exchange the first and last characters in a given string and return the new string.

Visual Presentation:

C# Sharp: Basic Algorithm Exercises - Exchange the first and last characters in a given string and return the new string.

Sample Solution:

C# Sharp Code:

using System;

// Namespace declaration
namespace exercises
{
    // Class declaration
    class Program
    {
        // Main method - entry point of the program
        static void Main(string[] args)
        {
            // Calling the 'test' method with different strings and displaying the returned values
            Console.WriteLine(test("abcd"));  // Output: "dbca"
            Console.WriteLine(test("a"));     // Output: "a"
            Console.WriteLine(test("xy"));    // Output: "yx"
            Console.ReadLine();               // Keeping the console window open
        }

        // Method to perform a specific string transformation
        public static string test(string str)
        {
            // Checking if the length of the input string is greater than 1
            // If yes, the transformation is performed; otherwise, the input string is returned as is
            return str.Length > 1
                // Ternary operator used to rearrange characters based on certain positions
                ? str.Substring(str.Length - 1) + str.Substring(1, str.Length - 2) + str.Substring(0, 1)
                // Returns the input string itself if its length is 1 or 0
                : str;
        }
    }
}

Sample Output:

dbca
a
yx

Flowchart:

For more Practice: Solve these Related Problems:

Write a C# program to rotate a string left by one and swap the new first and last characters.
Write a C# program to swap the second and second-last characters of a string, if they exist.
Write a C# program to reverse a string if the first and last characters are the same.
Write a C# program to exchange the first three and last three characters of a string of at least 6 characters.

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