Parser for signed overpunch values?

Question

I am working with some old data imports and came across a bunch of data from an external source that reports financial numbers with a signed overpunch. I\'ve seen alot, but

Answer 1

Here are two other approaches, so you have more alternatives to choose from:

public static int Overpunch2Int_v1(string number)
{
    number = number.ToLower();
    char last = number.Last();
    number = number.Substring(0, number.Length - 1);
    if (last == '}' || (last >= 'j' && last <= 'r'))
    {
        number = "-" + number;
        if (last == '}')
            number += "0";
        else
            number += (char)(last - 'j' + '1');
    }
    else if (last == '{' || (last >= 'a' && last <= 'i'))
    {
        if (last == '{')
            number += "0";
        else
            number += (char)(last - 'a' + '1');
    }

    return Int32.Parse(number);
}

public static int Overpunch2Int_v2(string number)
{
    number = number.ToLower();
    char last = number.Last();
    number = number.Substring(0, number.Length - 1);

    if (last >= '{')
        number = (last == '}'? "-" : "") + number + "0";
    else if (last >= 'a' && last <= 'r')
    {
        bool isNegative = last >= 'j';
        char baseChar = isNegative ? 'j' : 'a';
        number = (isNegative ? "-" : "") + number + (char)(last - baseChar + '1');
    }

    return Int32.Parse(number);
}

Please note that both methods don't validate the string and expect a valid number.