preg_match_all无法在php中工作，但在在线正则表达式测试中成功测试过

Question

I'm trying to match all lines in a string which start and end with a vertical bar "|". I have tried out different patterns and tested the pattern '/^\|.*\|$/m' successfully using the online tester https://regex101.com/.

However, when I put the same successfully tested pattern into my php script, it does not work. This is a sample code:

$re = '/^\|.*\|$/m';
$str = 'Why is this not working?

|Test|
|Test|
|Test|
|Test|
';

preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
var_dump($matches);

This code outputs

array(0) {
}

which means the pattern did not find any match. It is driving me crazy. What am I doing wrong?

Answer 1

With this regex should work

$re = '/^\|.*\|$/m';

http://sandbox.onlinephpfunctions.com/code/44c7d929742a58ca81f9e7ffad4587d9a4854b15