C#: Reverse the case of all characters of given string

Last update on August 25 2025 12:50:24 (UTC/GMT +8 hours)

Write a C# Sharp program to reverse the case (upper->lower, lower->upper) of all the characters in a given string.

Sample Solution:-

C# Sharp Code:

using System;
using System.Linq;

namespace exercises
{
    class Program
    {
        static void Main(string[] args)
        {
            // Display the original string and its case-reversed version for different inputs
            Console.WriteLine("Original string: PHP");
            Console.WriteLine("After reversing the case of all characters of the said string: " + test("PHP"));

            Console.WriteLine("\nOriginal string: JavaScript");
            Console.WriteLine("After reversing the case of all characters of the said string: " + test("JavaScript"));

            Console.WriteLine("\nOriginal string: Python 3.0");
            Console.WriteLine("After reversing the case of all characters of the said string: " + test("Python 3.0"));
        }

        // Method to reverse the case of all characters in the input string
        public static string test(string text)
        {
            // Using LINQ, iterate through each character in the string and reverse its case
            // If the character is uppercase, convert it to lowercase, and vice versa
            return string.Concat(text.Select(x => char.IsUpper(x) ? char.ToLower(x) : char.ToUpper(x)));
        }
    }
}

Sample Output:

Original string: PHP
After reversing the case of all characters of the said string: php

Original string: JavaScript
After reversing the case of all characters of the said string: jAVAsCRIPT

Original string: Python 3.0
After reversing the case of all characters of the said string: pYTHON 3.0

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C# Sharp Code Editor:

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