Handy C# Regular Expressions


Have you ever been looking for handy RegExp's.  I have grabbed a few I use from time to time and have put them below.




//Find first non-digit
Regex firstNonDigitIndexRegexp = new Regex(@"\D",RegexOptions.RightToLeft);

//Test if a string ends with a digit
Regex endsWithDigitRegexp = new Regex(@"\d$");      

//Test if a string starts with a digit
Regex startsWithDigitRegexp = new Regex(@"^\d");

//Find the last digit in a string
Regex lastDigitIndexRegexp = new Regex(@"\d", RegexOptions.RightToLeft);

//Test if a string contains only digits
Regex numbersOnlyRegExp = new Regex(@"\D");

//Validate an email address
public bool ValidateEmail(string  EmailAddress)
     string patternToMatch = @"^([a-zA-Z0-9_\+\-\.]+)@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.)|(([a-zA-Z0-9\-]+\.)+))([a-zA-Z]{2,4}|[0-9]{1,3})(\]?)$";
     System.Text.RegularExpressions.Match match = Regex.Match(EmailAddress, patternToMatch, RegexOptions.IgnoreCase);
     return match.Success;

// Validate a URL
public static bool IsUrlValid(string url)
     //ensure we have a valid prefix
     if(!Regex.IsMatch(url, @"^(http|https)\:(\\\\|//)", RegexOptions.IgnoreCase))            
          url = String.Concat("http://", url);   //default to http

     string pattern = @"^(http|https)\://[a-zA-Z0-9\-\.]+\.[a-zA-Z]{2,3}(:[a-zA-Z0-9]*)?/?([a-zA-Z0-9\-\._\?\,\'/\\\+&%\$#\=~])*[^\.\,\)\(\s]$";
     Regex reg = new Regex(pattern, RegexOptions.Compiled | RegexOptions.IgnoreCase);
     return reg.IsMatch(url);




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