Regex to Match White Space or End of String

Question

I'm trying to find every instance of @username in comment text and replace it with a link. Here's my PHP so far:

$comment = preg_replace('/@(.+?)\s/', '<a href="/users/${1}/">@${1}</a> ', $comment);

The only problem is the regex is dependent upon there being whitespace after the @username reference. Can anyone help me tweak this so it will also match if it is at the end of the string?

Max Shawabkeh · Accepted Answer · 2010-03-22 07:20:05Z

14

To detect whitespace or end of string, you would use: /@(.+?)(?=\s|$)/, but unless your usernames contain non-alphanumeric characters, it's simpler to use the \w for word character or \b for word break, i.e.: /@(.+?)\b/ or /@(\w)+/.

edited Mar 22, 2010 at 7:20

answered Mar 22, 2010 at 7:06

Max Shawabkeh

38.7k10 gold badges85 silver badges92 bronze badges

Sign up to request clarification or add additional context in comments.

4 Comments

animuson Over a year ago

Or could we use that to determine whether to add a white-space at the end of the link? $comment = preg_replace('/@(.+?)(?:\s|$)/', '<a href="/users/${1}/">@${1}</a>${2}', $comment);

Max Shawabkeh Over a year ago

Yes, but in that case you'll have to use a capturing group (remove the ?:).

Kirk Ouimet Over a year ago

This actually was really helpful! Thanks for the white space fix

Kalle H. Väravas Over a year ago

(?=\s|$) a big big help for the regexly-challenged people! Thank you for that trick.

J-16 SDiZ · Accepted Answer · 2010-03-22 07:06:02Z

9

try /@(\w+)/ instead of /@(.+?)\s/.

answered Mar 22, 2010 at 7:06

J-16 SDiZ

27k4 gold badges67 silver badges86 bronze badges

2 Comments

Kirk Ouimet Over a year ago

Excellent - that worked perfectly! Can you tell me more about \w?

animuson Over a year ago

@Kirk: \w simply matches any 'word' character: A-Za-z0-9_

Collectives™ on Stack Overflow

Regex to Match White Space or End of String

2 Answers 2

4 Comments

2 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

4 Comments

2 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related