Question

I have the following pattern and subject

$pattern = "\[item\s*id=['\"](.*?)['\"]\s*\]";
$subject = "[item id=\"40\"]";

Basically, I want to get the id attribute from a string, [item id="30"].

And I’ve tested my pattern and subject on different preg_match and preg_match_all websites and they all return the correct matches.

However, the following code I wrote seems to always return NULL for matches.

preg_match_all($pattern, $subject, $matches);
var_dump($matches);

What’s wrong? How can I do this?

Answer 1

You’re missing delimiters:

Warning: preg_match_all(): Delimiter must not be alphanumeric or backslash in /data/1.php on line 4 NULL

So $pattern should look like:

$pattern = "~\[item\s*id=['\"](.*?)['\"]\s*\]~";

It returns:

array(2) { [0]=> array(1) { [0]=> string(14) "[item id="40"]" } [1]=> array(1) { [0]=> string(2) "40" } }