这个正则表达式有什么问题？ （适用于regex101.com）

Question

Can any of you spot my error - I have a regex that works just fine when I test it online - see https://www.regex101.com/r/tG2fI5/2

But it doesn't work in my code below. It outputs nothing when I print the $match array...

$output =   '<h2>Køretøj</h2>                       
            <div class="pairName">Mærke</div>
            <div class="pairValue">PEUGEOT</div>
            <div class="pairName">Model</div>
            <div class="pairValue">607</div>
            <div class="pairName">Stelnummer</div>
            <div class="pairValue">VFDDD4TZE92104255</div>
            <div class="pairName">Seneste reg.nr.</div>
            <div class="pairValue">YE45522</div>';

$pattern = '/(?<=pairValue">)(.*?)(?=<)/g'; 
$match = array();

preg_match_all($pattern, $output, $match);

print_r($match);

Answer 1

It looks like preg_match_all() automatically performs a global expression match.

See http://php.net/manual/en/function.preg-match-all.php.

So change

$pattern = '/(?<=pairValue">)(.*?)(?=<)/g';

to

$pattern = '/(?<=pairValue">)(.*?)(?=<)/';

I tested this with PHP 5.5 and it output the following:

Array
(
    [0] => Array
        (
            [0] => PEUGEOT
            [1] => 607
            [2] => VFDDD4TZE92104255
            [3] => YE45522
        )

    [1] => Array
        (
            [0] => PEUGEOT
            [1] => 607
            [2] => VFDDD4TZE92104255
            [3] => YE45522
        )

)

The first element in the array holds all matches. The second holds "is an array of strings matched by the first parenthesized subpattern" (also from the above link).

So you could also change the regex to /(?<=pairValue">).*(?=<)/ if that suits your needs.