try this exampal code using regex..
string input = "Week 9 (or) Current week: 2/24/2013 - 3/2/2013";
MatchCollection matches = Regex.Matches(input, @"\d{1,2}/\d{1,2}/\d{4}");
DateTime dt =DateTime.Parse(matches[0].Value);
DateTime dt2 = DateTime.Parse(matches[1].Value);
also go through following link
Regular expression - String followed by a date[
^]