CounterID -TizzyT

// A base62 ID generator based on a counter

public class CounterID
{
    private const char _lastNum = '9', _lastAlphaLower = 'z', _lastAlphaUpper = 'Z'; // constants

    private readonly char[] _counter = "0000000000".ToCharArray(); // ten character starting value

    public void Increment() => Increment(9); // public method which doesnt expose any parameters
    private void Increment(int position) // private method for internal use
    {
        if (position == -1) return; // enables wrap around ex: ZZZZZZZZZZ increments to 0000000000
        switch (_counter[position])
        {
            case _lastNum:
                _counter[position] = 'a';
                break;
            case _lastAlphaLower:
                _counter[position] = 'A';
                break;
            case _lastAlphaUpper:
                _counter[position] = '0';
                Increment(position - 1);
                break;
            default:
                _counter[position]++;
                break;
        }
    }

    public override string ToString() => new(_counter); // return the char[] as a string
}