should start with letter follow by letters and numbers and (-) - zero or more can't start or finish with (-) can't have two or more consecutive (-) char

This version matches any sentence that sounds like yelling even it doesnt end with ? or !

Bob answers 'Whoa, chill out!' if you yell at him. You can use this regex to match regexes like "WHAT THE HELL WERE YOU THINKING?"

Match a not-empty string. A string with only spaces or no characters is an empty-string. When match something, mathc all the string with the exception of the eventually space at the and

Validador de CPF

White space

correctly handle the case where the value is splitted on multiple lines.

A powerful regex (fewest steps possible) which gives you all the information about urls.

Fully qualified domain name validation