Parsing formatted string

While the comments about lost information are valid, sometimes you just want to get the string values of of a string with known formatting.

One method is this blog post written by a friend of mine. He implemented an extension method called string[] ParseExact(), akin to DateTime.ParseExact(). Data is returned as an array of strings, but if you can live with that, it is terribly handy.

public static class StringExtensions
{
    public static string[] ParseExact(
        this string data, 
        string format)
    {
        return ParseExact(data, format, false);
    }

    public static string[] ParseExact(
        this string data, 
        string format, 
        bool ignoreCase)
    {
        string[] values;

        if (TryParseExact(data, format, out values, ignoreCase))
            return values;
        else
            throw new ArgumentException("Format not compatible with value.");
    }

    public static bool TryExtract(
        this string data, 
        string format, 
        out string[] values)
    {
        return TryParseExact(data, format, out values, false);
    }

    public static bool TryParseExact(
        this string data, 
        string format, 
        out string[] values, 
        bool ignoreCase)
    {
        int tokenCount = 0;
        format = Regex.Escape(format).Replace("\\{", "{");

        for (tokenCount = 0; ; tokenCount++)
        {
            string token = string.Format("{{{0}}}", tokenCount);
            if (!format.Contains(token)) break;
            format = format.Replace(token,
                string.Format("(?'group{0}'.*)", tokenCount));
        }

        RegexOptions options = 
            ignoreCase ? RegexOptions.IgnoreCase : RegexOptions.None;

        Match match = new Regex(format, options).Match(data);

        if (tokenCount != (match.Groups.Count - 1))
        {
            values = new string[] { };
            return false;
        }
        else
        {
            values = new string[tokenCount];
            for (int index = 0; index < tokenCount; index++)
                values[index] = 
                    match.Groups[string.Format("group{0}", index)].Value;
            return true;
        }
    }
}