preg_quote() bug or strange behavior?

I used preg_quote() to escape some special characters. But in the test below, there is something I can’t understand.

Why ‘date:1111aaa’ doesn’t match ???

<?php
$PregArray = ['date:1111aaa', ':222aaa', '@odia tvled'];


$array['attract (step-date:1111aaa)'] = 'OK';
$array['type (step-date:222aaa)'] = 'OK';
$array['@odia tvled'] = 'OK';


foreach ($PregArray as $key_1 => $val_1) {
    echo "n--------------";
    foreach ($array as $key_2 => $val_2) {
        if (preg_match("~$val_1~", preg_quote($key_2))) {
            echo "nOK => $val_1 - ".preg_quote($key_2);
            break;
            }
        else {
            echo "nNOK !!! => $val_1 - ".preg_quote($key_2);
            }
        }
    }

http://sandbox.onlinephpfunctions.com/code/9ef36e2b010ac1f4f0eaf08881004892bd0cd9c4

Answer

You’re using preg_quote in the wrong place, it is intended for escaping characters in the pattern, not the test string (see the manual). Change your code to this and it works fine:

foreach ($PregArray as $key_1 => $val_1) {
    echo "n--------------";
    foreach ($array as $key_2 => $val_2) {
        if (preg_match('~' . preg_quote($val_1) . '~', $key_2)) {
            echo "nOK => $val_1 - $key_2";
            break;
            }
        else {
            echo "nNOK !!! => $val_1 - $key_2";
            }
        }
    }

Output:

--------------
OK => date:1111aaa - attract (step-date:1111aaa)
--------------
NOK !!! => :222aaa - attract (step-date:1111aaa)
OK => :222aaa - type (step-date:222aaa)
--------------
NOK !!! => @odia tvled - attract (step-date:1111aaa)
NOK !!! => @odia tvled - type (step-date:222aaa)
OK => @odia tvled - @odia tvled

Demo on 3v4l.org