Match Special Letters with PHP Regular Expressions

By  on  

Regular expressions come with all sorts of peculiarities, one of which I recently ran into when creating a regex within PHP and preg_match.  I was trying to parse strings with the format "Real Name (:username)" when I ran into a problem I would see a lot at Mozilla:  my regular expression wasn't properly catching "special" or "international" letters, like à, é, ü, and the dozens of others.

My regular expression was using A-z in the real name matching piece of the regex, which I assumed would match special letters, but it did not:

preg_match(
  "/([A-Za-z -]+)?\s?\[?\(?:([A-Za-z0-9\-\_]+)\)?\]?/", 
  "Yep Nopé [:ynope]", $matches);

// 0 => '[:ynope]', 1 => 'Yep Nopé', 2 => 'ynope'

To match international letters, I needed to update my regular expression in two ways:

  • Change A-z to \pL within the matching piece
  • Add the u modifier makes the string treated as UTF-8

The updated regex would be:

preg_match(
  "/([\pL -]+)?\s?\[?\(?:([\pL0-9\-\_]+)\)?\]?/u", 
  "Yep Nopé [:ynope]", $matches);

// 0 => 'Yep Nopé [:ynope]', 1 => 'Yep Nopé', 2 => 'ynope'

You can see my simple test bed here. If you're afraid that other characters might seep in, or don't trust \pL, you could list every special letter manually (i.e. [A-zàáâä....])

One of the nice parts of working at a truly global organization like Mozilla is that I'm exposed to many edge cases; in this case, a few special letters!

Recent Features

  • By
    Send Text Messages with PHP

    Kids these days, I tell ya.  All they care about is the technology.  The video games.  The bottled water.  Oh, and the texting, always the texting.  Back in my day, all we had was...OK, I had all of these things too.  But I still don't get...

  • By
    Animated 3D Flipping Menu with CSS

    CSS animations aren't just for basic fades or sliding elements anymore -- CSS animations are capable of much more.  I've showed you how you can create an exploding logo (applied with JavaScript, but all animation is CSS), an animated Photo Stack, a sweet...

Incredible Demos

Discussion

  1. [A-z] doesn’t do what you seem to quite what you think it does. That character range includes the characters in the ASCII table between Z and a: [\]^_. It looks like you should be using [A-Za-z].

Wrap your code in <pre class="{language}"></pre> tags, link to a GitHub gist, JSFiddle fiddle, or CodePen pen to embed!