Using nested foreach loop on same array

Question

Is it ok to loop array again in nested loop and also change the array?

I've an URL's array with entries(as array key) of either an URL or domain:example.com

In case of this entry : domain:example.com I want to remove all URLS containing example.com as domain:

foreach (array_keys($urls1) as $line) {
        if (preg_match('/domain:(.*)/i', $line, $matches)) {
            $domain = $matches[1];
            foreach (array_keys($urls1) as $line2) {
                if ($url_domains[$line2] == $domain) {
                    unset($urls1[$line2]);
                }
            }
        }
    }

Answer 1

There is no problem looping over it a second time, however you will get yourself and your code into a big knot if you start removing items. My suggestion would be to save a copy and modify that.

This is not ideal, but I'm not sure what you wish to do.

//Make a copy of your array
$URLCopy  = $urls1;

foreach (array_keys($urls1) as $line) {
    if (preg_match('/domain:(.*)/i', $line, $matches)) {
        $domain = $matches[1];
        foreach (array_keys($urls1) as $line2) {
            if ($url_domains[$line2] == $domain) {
                unset($URLCopy[$line2]);
            }
        }
    }
 }