This expression can be used for identifying if a string (such as a dialed number using a cloud based telephony service) matches one of the known North American US N11 Service Numbers. It will match if the number is in e.164 format or not, and only matches when the string begins and ends with the des...

Valid format YYYY-MM-DD

Find emoji's in strings.

Usernames are used everywhere on the internet. They are what give users a unique identity on their favorite sites. You need to check all the usernames in a database. Here are some simple rules that users have to follow when creating their username. 1) The only numbers in the username have to be at...

This is regex for website url matching scheme,host,port,path and query. I did it because in c#, class Uri does not understand urls without scheme and says that 'google.com' is invalid url.

parses accept language http header groups: language code iso-693-1 without country specification preference quality value

Pipe tables format for R Markdown

Regex for date in ISO 8601 format that also check the number of day in a month to be sure the date is valid

Validates IPv4 IP Address

break the code to first opening parenthesis and then closing use the groups individually not entirely . This is 40% correct online pattern but mixing it with first open then close groups in two different matches result in 100% success