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Matches the first part of a UK Postcode (known as a postcode district). Case insensitive. Doesnt match: GIR # the postcode for the formerly Post Office-owned Girobank is GIR 0AA. SAN # the postcode for correctly addressed letters to Father Christmas is SAN TA1

This regex only matches clean domain names. No path after. Ends in a forward slash. Starts with http://www. It is pretty slack on the TLD requiring a 2 or 3 letter ending. This part could be tightened up if you wanted to be restrict it to specific TLDs.

Allows dashes or spaces to separate.

Allows dashes or spaces to separate.

Allows dashes or spaces to separate.

Allows dashes or spaces to separate.

Allows dashes or spaces to separate.

Validates the format of a UK bank sort code.

UK Bank account numbers are 8 digits. One bank uses 7 digits so in the validation error message you should instruct the user to prefix with a zero of their code is too short. If you want to allow the 7 digit codes as well use this regex: http://regexlib.com/REDetails.aspx?regexp_id=2707

UK Bank Account. One bank account issues 7 digit bank codes and you should prefix a 0 yourself after input. If you want strict validation of 8 characters use this regex: http://regexlib.com/REDetails.aspx?regexp_id=2706

No whitespace is allowed in a string

This might seem like a contrived example but it was written to answer a question on a forum. For regex newbies you can just change the numbers in {} to change the number of required digits to suit your requirements

This is a simple regular expression which allows 1 to 99 in .5 increments which I originally developed for a forum post

Based on the source listed below. I have added in the 05 prefix for allowing UK voip landlines. I dont know if the spacings are all ofcom approved like the original regex but the patterns it supports are: 029 99999999 or 029 9999 9999; 0199 9999999 or 0199 999 9999; 01999 99999; 01999 999999; 019999 9999; 019999 99999; 0599 9999999 or 0599 999 9999; 05999 99999; 05999 999999; 059999 9999; 059999 99999;

Based on ip regex listed in source. Expanded to require udp:// or norm:// protocol at the start and :12345 port number at the end (1-5 digits). Written to answer a forum question. Current limitations - only allows lowercase protocol names and doesn't block ports that start with 0.

This was based on the regex in the source but it was buggy so I fixed it and then optimized it. It matches port numbers in the form of :1 to :65535 This is designed to be plugged onto the end of your favourite url regex because when I was looking for a IPv4 regex I noticed that a lot of them either didn't match the port or matched it badly (allowing the port number to start with a 0 or be higher than 65535) This regex solves those two problems.

This is the same as my regex listed in the source except that it is wrapped in (regex)? which makes it optional. The intended use for this regex is to be combined with buggy url/ip regex's to strengthen the port matching. It matches port numbers in the form of :1 to :65535 and also allows no port to be entered. I noticed that a lot of url/ip regexs either didn't match the port or matched it badly (allowing the port number to start with a 0 or be higher than 65535) This regex solves those two problems.

This uses named groups to extract the user and domain portions of an Active Directory user in user@domain format. You can use the following c# code to convert this into domain\user format: public string ConvertUserAtDomainToDomainUser(string userAtDomain) { return Regex.Replace(userAtDomain, @"^(?<user>.+)@(?<domain>.+)$", @"${domain}\${user}"); } This regex is intended to provide extraction from valid user@domain strings rather than validate its format.

This will match a youtube url and pull the video id out into a named capture group called VideoID. It is intentionally loose on the length and content of the video id so that it doesn't break in the future if YouTube change the format.

Allows http and https, bans www prefix, username portion is clamped to the rules it gives you at signup and also allows an optional trailing slash. [UPDATED] allows the #! notation that twitter used.