using System;

public class Program

{

    public static void Main()

    {

        var plagKenneth1 = "";

        var plagKenneth2 = "a";

        var plagKenneth3 = "alle fugler små de er";

        Console.WriteLine("1: " + plagKenneth1.ToUpperFirstCharacter());

        Console.WriteLine("2: " + plagKenneth2.ToUpperFirstCharacter());

        Console.WriteLine("3: " + plagKenneth3.ToUpperFirstCharacter());

    }

}

​

public static class StringExtensions

{

    public static string ToUpperFirstCharacter(this string value)

    {

        if (string.IsNullOrEmpty(value))

        {

            return value;

        }

​

        return char.ToUpper(value[0]) + value[1..];

    }

}