C#: Convert the last 3 characters of a given string in upper case

Last update on June 25 2025 13:04:03 (UTC/GMT +8 hours)

Uppercase Last Three Characters

Write a C# Sharp program to convert the last 3 characters of a given string to uppercase. If the length of the string is less than 3, then uppercase all the characters.

Visual Presentation:

C# Sharp: Basic Algorithm Exercises - Convert the last 3 characters of a given string in upper case.

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)
        {
            // Printing results of the test method with various inputs
            Console.WriteLine(test("Python"));
            Console.WriteLine(test("Javascript"));
            Console.WriteLine(test("js"));
            Console.WriteLine(test("PHP"));
            Console.ReadLine(); // Allowing user to read the output before the console closes
        }

        // Method to modify a string according to the condition
        public static string test(string str)
        {
            // Ternary operator: If the length of the string is less than 3, return the uppercase string. 
            // Otherwise, remove the last 3 characters, convert them to uppercase, and append them back.
            return str.Length < 3 ? str.ToUpper() : str.Remove(str.Length - 3) + str.Substring(str.Length - 3).ToUpper();
        }
    }
}

Sample Output:

PytHON
JavascrIPT
JS
PHP

Flowchart:

For more Practice: Solve these Related Problems:

Write a C# program to convert the first three characters of a string to lowercase. If the string has less than 3 characters, lowercase all of them.
Write a C# program to convert every third character of a string to uppercase starting from the end.
Write a C# program to uppercase the last 3 characters only if they are alphabetic; otherwise, leave the string unchanged.
Write a C# program that reverses a string and then uppercases the first three characters of the reversed string.

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