PHP preg_match unknown modifier error

Question

Message: preg_match(): Unknown modifier 'p'

Filename: core/Router.php

Line Number: 399

Backtrace:

File: /home/spdcin/public_html/demo/no-waste/index.php Line: 292 Function: require_once iam getting this error on line 2

$key = str_replace(array(':any', ':num'), array('[^/]+', '[0-9]+'), $key);

        // Does the RegEx match?
         //line no 2
        if (preg_match('#^'.$key.'$#', $uri, $matches))
        {
            // Are we using callbacks to process back-references?
            if ( ! is_string($val) && is_callable($val))
            {
                // Remove the original string from the matches array.
                array_shift($matches);

                // Execute the callback using the values in matches as its parameters.
                $val = call_user_func_array($val, $matches);
            }
            // Are we using the default routing method for back-references?
            elseif (strpos($val, '$') !== FALSE && strpos($key, '(') !== FALSE)
            {
                $val = preg_replace('#^'.$key.'$#', $val, $uri);
            }

            $this->_set_request(explode('/', $val));
            return;
        }
    }

Possible duplicate of [Warning: preg\_replace(): Unknown modifier '\]'](https://stackoverflow.com/questions/20705399/warning-preg-replace-unknown-modifier) — Toto, Jul 04 '19 at 13:26

Gabriel Hautclocq · Answer 1 · 2016-05-07T09:19:08.507

1

There is a problem with your regex and PHP thinks you try to apply a 'p' modifier, which is not valid.

You will probably get to know what is wrong with your regex if you do :

echo '#^'.$key.'$#';

The fact that you try to program a router indicates that $key most probably contains '#p' (common in URLs).

Solution : In your case you can escape the character '#' with backslashes. Quoted from the php documentation : "If the delimiter needs to be matched inside the pattern it must be escaped using a backslash."

edited May 07 '16 at 09:19

answered May 07 '16 at 09:07

Gabriel Hautclocq

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i understood my problem but how to overcome from that – user_777 May 07 '16 at 09:11

score 0 · Answer 2 · answered May 09 '16 at 21:48

0

If I understand your problem correctly, surround $key with preg_quote() like this:

if (preg_match('#^'.preg_quote($key).'$#', $uri, $matches))

This function will automatically escape ALL regex commands in $key.

answered May 09 '16 at 21:48

Platinum Fire

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PHP preg_match unknown modifier error

2 Answers2