I am trying get a regex to match a url with following rules:

• https - mandatory
• www - optional
• subdomain, empty or any of sub1 and sub2
• domain - fixed, mandatory. google.com

So far I got: ^https:\/\/(w{0,3})(sub1|sub2)\.google\.com$

Can't make it work to allow empty subdomain, i tried (^$|sub1|sub2) in subdomain capturing group, but doesn't work. Also . after www or before domain name, it's conditional.

examples:

• https://google.com - match
• https://www.google.com - match
• https://sub1.google.com - match
• https://www.sub1.google.com - match
• https://sub2.google.com - match
• https://www.sub2.google.com - match
• http:<anything> - do not match
• https://sub3.google.com - do not match

CodePudding user response：

Try this: ^https:\/\/(w{0,3}\.)?(sub1\.|sub2\.)?google\.com$

Test here: https://regex101.com/r/imwunj/1

In your regex dots after www and sub's were not being matched, so once you make them optional, the regex works.