An invalid regex pattern

This is invalid…

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You can also test the validity of regular expressions in real-time at http://regexhero.net/tester/

By the way, you don’t actually have to test the regular expression against a string to see if it’s valid. You can simply instantiate a new Regex object and catch the exception.

This is what Regex Hero does to return a detailed error message…

public string GetRegexError(string _regexPattern, RegexOptions _regexOptions)
{
    try
    {
        Regex _regex = new Regex(_regexPattern, _regexOptions);
    }
    catch (Exception ex)
    {
        return ex.Message;
    }

    return "";
}