Regex for names with special characters (Unicode)

Question

Okay, I have read about regex all day now, and still don't understand it properly. What i'm trying to do is validate a name, but the functions i can find for this on the internet only use [a-zA-Z], leaving characters out that i need to accept to.

I basically need a regex that checks that the name is at least two words, and that it does not contain numbers or special characters like !"#¤%&/()=..., however the words can contain characters like æ, é, Â and so on...

An example of an accepted name would be: "John Elkjærd" or "André Svenson"
An non-accepted name would be: "Hans", "H4nn3 Andersen" or "Martin Henriksen!"

If it matters i use the javascript .match() function client side and want to use php's preg_replace() only "in negative" server side. (removing non-matching characters).

Any help would be much appreciated.

Update:
Okay, thanks to Alix Axel's answer i have the important part down, the server side one.

But as the page from LightWing's answer suggests, i'm unable to find anything about unicode support for javascript, so i ended up with half a solution for the client side, just checking for at least two words and minimum 5 characters like this:

if(name.match(/\S+/g).length >= minWords && name.length >= 5) {
  //valid
}

An alternative would be to specify all the unicode characters as suggested in shifty's answer, which i might end up doing something like, along with the solution above, but it is a bit unpractical though.

Answer 1

Try the following regular expression:

^(?:[\p{L}\p{Mn}\p{Pd}\'\x{2019}]+\s[\p{L}\p{Mn}\p{Pd}\'\x{2019}]+\s?)+$

In PHP this translates to:

if (preg_match('~^(?:[\p{L}\p{Mn}\p{Pd}\'\x{2019}]+\s[\p{L}\p{Mn}\p{Pd}\'\x{2019}]+\s?)+$~u', $name) > 0)
{
    // valid
}

You should read it like this:

^   # start of subject
    (?:     # match this:
        [           # match a:
            \p{L}       # Unicode letter, or
            \p{Mn}      # Unicode accents, or
            \p{Pd}      # Unicode hyphens, or
            \'          # single quote, or
            \x{2019}    # single quote (alternative)
        ]+              # one or more times
        \s          # any kind of space
        [               #match a:
            \p{L}       # Unicode letter, or
            \p{Mn}      # Unicode accents, or
            \p{Pd}      # Unicode hyphens, or
            \'          # single quote, or
            \x{2019}    # single quote (alternative)
        ]+              # one or more times
        \s?         # any kind of space (0 or more times)
    )+      # one or more times
$   # end of subject

I honestly don't know how to port this to Javascript, I'm not even sure Javascript supports Unicode properties but in PHP PCRE this seems to work flawlessly @ IDEOne.com:

$names = array
(
    'Alix',
    'André Svenson',
    'H4nn3 Andersen',
    'Hans',
    'John Elkjærd',
    'Kristoffer la Cour',
    'Marco d\'Almeida',
    'Martin Henriksen!',
);

foreach ($names as $name)
{
    echo sprintf('%s is %s' . "\n", $name, (preg_match('~^(?:[\p{L}\p{Mn}\p{Pd}\'\x{2019}]+\s[\p{L}\p{Mn}\p{Pd}\'\x{2019}]+\s?)+$~u', $name) > 0) ? 'valid' : 'invalid');
}

I'm sorry I can't help you regarding the Javascript part but probably someone here will.

---

Validates:

• John Elkjærd
• André Svenson
• Marco d'Almeida
• Kristoffer la Cour

Invalidates:

• Hans
• H4nn3 Andersen
• Martin Henriksen!

---

To replace invalid characters, though I'm not sure why you need this, you just need to change it slightly:

$name = preg_replace('~[^\p{L}\p{Mn}\p{Pd}\'\x{2019}\s]~u', '$1', $name);

Examples:

• H4nn3 Andersen -> Hnn Andersen
• Martin Henriksen! -> Martin Henriksen

Note that you always need to use the u modifier.