How to formulate a regex to get Dates from specific strings?

i have the following strings:

Months:

Jan11

Feb11

Mar11

Apr11

etc.

Quarters:

Q1 11

Q2 11

Q3 11

Q4 11

Q1 12

etc.

Years

Cal_11

Cal_12

Cal_13

etc.

I would like to use a regular expression to create a DateTime object starting at the beginning of each date represented by a string. So Jan11 would be

new DateTime(2011,1,1)

, Q2 11 would be

new DateTime(2011,4开发者_开发百科,1)

and Cal_12 would be

new DateTime(2012,1,1).

This should take of all three cases:

DateTime? parse(string text)
{
    Match m = Regex.Match(text, @"^(\w\w\w)(\d+)$");
    if (m.Success)
    {
        return new DateTime(
            2000 + Convert.ToInt32(m.Groups[2].Value), 
            1 + Array.IndexOf(CultureInfo.CurrentCulture.DateTimeFormat.AbbreviatedMonthNames, m.Groups[1].Value), 
            1);
    }

    m = Regex.Match(text, @"^Q(\d+) (\d+)$");
    if (m.Success)
    {
        return new DateTime(
            2000 + Convert.ToInt32(m.Groups[2].Value), 
            1 + 3 * (Convert.ToInt32(m.Groups[1].Value) - 1), 
            1);
    }

    m = Regex.Match(text, @"^Cal_(\d+)$");
    if (m.Success)
    {
        return new DateTime(
            2000 + Convert.ToInt32(m.Groups[1].Value),
            1,
            1);
    }

    return null;
}

Calling like this:

parse("Jan11");
parse("Q2 11");
parse("Cal_12");

Please note that this doesn't account for incorrect data passed in. This could be added obviously, but would make the example quite cluttered.