Increment an index that uses numbers and characters (aka Base36 numbers)

Question

I have a string based code that can be either two or three characters in length and I am looking for some help in creating a function that will increment it.

Each \'

Answer 1

Based on @Martin answer, I found some error when two ZZ comes, this makes exception in code

private static String Increment(String s,bool IsFromRecursion=false)
{
    String chars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";

    //Added this condition
    if (IsFromRecursion && string.IsNullOrEmpty(number))
    {
         return "1";
    }
    //Added this condition

    char lastChar = s[s.Length - 1];
    string fragment = s.Substring(0, s.Length - 1);

    if (chars.IndexOf(lastChar) < 35)
    {
        lastChar = chars[chars.IndexOf(lastChar) + 1];

        return fragment + lastChar;
    }

    return Increment(fragment,true) + '0';
}

When we call this method we pass first parameter only.