C# adding a character in a string

Question

I know I can append to a string but I want to be able to add a specific character after every 5 characters within the string

from this string alpha = abcdefghijklmno

Answer 1

Here is my solution, without overdoing it.

    private static string AppendAtPosition(string baseString, int position, string character)
    {
        var sb = new StringBuilder(baseString);
        for (int i = position; i < sb.Length; i += (position + character.Length))
            sb.Insert(i, character);
        return sb.ToString();
    }


    Console.WriteLine(AppendAtPosition("abcdefghijklmnopqrstuvwxyz", 5, "-"));