Create regex to check domain and URL

Question

Can someone please help me build regex to make sure that a string starts with one of the following?

https://www.youtube.com
https://www.youtube.be
http://www.youtube.com
http://www.youtube.be
https://youtube.com
https://youtube.be
http://youtube.com
http://youtube.be
www.youtube.com
www.youtube.be
youtube.com
youtube.be

I am working in on PHP system that allows people to add a YouTube video to a web page, I only need to make sure that the link users add begins appropriately and is also a valid URL. That should be then be safe enough for the string to be stored after the user has entered it and also embedded as a YouTube video when viewed later.

regexr.com is a very well made site to learn regex and try out this kind of things — Florian Moser
– Florian Moser, Commented Jul 31, 2016 at 13:35

nicael · Accepted Answer · 2016-07-31 13:17:51Z

1

That's as simple as

^(https?:\/\/)?(www\.)?youtube\.(be|com)

Little bit of explanation:

^ - start of the string
https? - http with optional s
:\/\/ - ://
(www\.)? - optional www.
youtube\. - youtube.
(be|com) - be or com

If you also want to match youtu.be, use this:

^(https?:\/\/)?(www\.)?(youtube\.(be|com)|youtu\.be)

edited Jul 31, 2016 at 13:17

answered Jul 31, 2016 at 12:25

nicael

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4 Comments

Peter Bushnell Over a year ago

Does that check for http and https?

Peter Bushnell Over a year ago

Thanks. Will test later when back on the job and report back.

nicael Over a year ago

@Peter added explanation in case you don't understand something immediately.

Peter Bushnell Over a year ago

That's perfect, thanks for your answer and the additional explanation.

Andrew Nodermann · Accepted Answer · 2016-07-31 13:49:54Z

0

((?:https?:\/\/)?(?:www.)?youtu(?:\.?be)?\.(?:com|be))

Includes:

https://www.youtube.com
https://www.youtube.be
http://www.youtube.com
http://www.youtube.be
https://youtube.com
https://youtube.be
http://youtube.com
http://youtube.be
www.youtube.com
www.youtube.be
youtube.com
youtube.be
youtu.be
www.youtu.be
http://www.youtu.be
https://www.youtu.be
http://youtu.be
https://youtu.be

PHP:

$re = "/((?:https?:\\/\\/)?(?:www.)?youtu(?:\\.?be)?\\.(?:com|be))/"; 
$str = "https://www.youtube.com\nhttps://www.youtube.be\nhttp://www.youtube.com\nhttp://www.youtube.be\nhttps://youtube.com\nhttps://youtube.be\nhttp://youtube.com\nhttp://youtube.be\nwww.youtube.com\nwww.youtube.be\nyoutube.com\nyoutube.be\nyoutu.be\nwww.youtu.be\nhttp://www.youtu.be\nhttps://www.youtu.be\nhttp://youtu.be\nhttps://youtu.be\n\n\nbsadf.fds\n\nyoutube\.(be|com)"; 

preg_match_all($re, $str, $matches);

UPD: Yes, @nicael is right, but I would change so:

((?:https?:\/\/)?(?:www\.)?(?:youtube\.(?:be|com)|youtu\.be))

edited Jul 31, 2016 at 13:49

answered Jul 31, 2016 at 12:45

Andrew Nodermann

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1 Comment

nicael Over a year ago

OP didn't really ask for youtu.be. Although, you've implemented it incorrectly anyway. Matches youtu.com, for example.

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