php - Regular expression for checking website url

Question

I need to check the web address, using regular expression.

if user type url as

1. www.test.com
2. http://www.test.com
3. https://www.test.com

i have a regular expression like

/^(http://[a-zA-Z0-9_-]+(?:.[a-zA-Z0-9_-]+)*.[a-zA-Z]{2,4}(?:/[a-zA-Z0-9_]+)*(?:/[a-zA-Z0-9_]+.[a-zA-Z]{2,4}(?:?[a-zA-Z0-9_]+=[a-zA-Z0-9_]+)?)?(?:&[a-zA-Z0-9_]+=[a-zA-Z0-9_]+)*)$/

but it will only allow the second option only. how can i modify the regular expression so that , it should accept 1st and 3rd option too

Answer 1

This is a pretty basic expression for testing domain names:

@^(http://|https://)?([a-z0-9][a-z0-9-]*.)+[a-z0-9][a-z0-9-]*$@i

Should match:

domain.com
www.domain.com
http://domain.com
https://domain.com