RegEx Match only first part of URL and use this as variable

Question

Always been struggeling with RegEx, help is much appreciated. I want to match parts of a URL with Regex but cannot get my head around it.

Domains are:

https:// name .secondpart.thirdpart.com

I want my regex to match

name How would I achieve this?

Started with (?<=^|\.) and (?<=^|\.)secondpart\.thirdpart\.com$ but it didn't work.

Answer 1

Note that I escaped the slashes using leading backslashes, assuming you use slash as your regex delimiter. If you use no or a different delimiter (eg #) you can just use / instead of \/ .

---

If you only care about the first part, then

^[^.:\/]+:\/\/([^.]+)

should do the trick.

https://regex101.com/r/CXXOOD/1

---

If you for also need to enforce a specific domain after that then capture it in a group like this

^[^.:\/]+:\/\/([^.]+)\.secondpart\.thirdpart\.com$

https://regex101.com/r/gjfYhC/1

---

If you want to make sure that at exactly 3 parts come after the sub-domain part, but don't care what they are:

^[^.:\/]+:\/\/([^.]+)(?:\.[^.]+){3}$

https://regex101.com/r/lUYBkT/1

Answer 2

As you tagged pcre, you can use:

^https?://\K[^\s./]+

Explanation

• ^ Start of string
• https?:// Match the protocol with an optional s
• \K Forget what is matched so far
• [^\s./]+ Match 1+ times a non whitespace char except . and /

See a regex demo .

Answer 3

You can use it,

(?:http[s]*\:\/\/)*(.*?)\.(?=[^\/]*\..{2,5})