A good majority of my work is for mobile applications using the Compact Framework. Something really annoying I came across today was that if I used a variable for the pattern in my Regex then the IsMatch did not work, but if I used a constant then it did.
So, for example, if I used:
string val = "YELLOW";
string pattern = "(YELLOW)$";
The following statement does not give the correct result (true):
bool flg1 = Regex.IsMatch("YELLOW", pattern);
But the following does:
bool flg2 = Regex.IsMatch(val, "(YELLOW)$");
So far I have not found a workaround (e.g. creating a Regex object and trying to use IsMatch using it also does not work if the pattern is from a var), but am investigating... if anybody has a solution then please let me know...
26 March 2009 - Okay, a colleague has finally helped me out with this one. There is a workaround so instead of using the IsMatch, rather return a Match object and then use the Success property to determine if the match was successful. Thanks Rich!
Regex r = new Regex(this.txtPattern.Text), RegexOptions.IgnoreCase);
bool pass = r.Match(this.txtInput.Text).Success;
this.txtFeedback.Text = (pass ? "Matched" : "No match");