Error during a preg_match_all in PHP

Question

I need to check if a string contains a particular words.

My code is the following:

// Get index.html source
$html = file_get_contents('extract/index.html');

// Bad words checker
$badWords = array("iframe", "alert");
$matches = array();
$matchFound = preg_match_all("/\b(" . implode($badWords,"|") . ")\b/i", $html, $matches);

if ($matchFound) {
    $words = array_unique($matches[0]);
    foreach($words as $word) {
        $results[] = array('Error' => "Keyword found : ". $word);
    }
}
else {
    $results[] = array('Success' => "No keywords found.");
}

Each time I want to execute this, I have the following warning:

Warning: preg_match_all(): Unknown modifier 'w' in /home/public_html/upload.php on line 131

Line 131:

$matchFound = preg_match_all("/\b(" . implode($badWords,"|") . ")\b/i", $html, $matches);

Do you know why ?

Thanks.

Update your code so you can output the regular expression and see what it *really* is at runtime. — Jason McCreary, Feb 10 '15 at 19:44
@AbraCadaver The arguments are in the [wrong order](http://php.net/implode). — Sverri M. Olsen, Feb 10 '15 at 19:47
`Note: implode() can, for historical reasons, accept its parameters in either order. For consistency with explode(), however, it may be less confusing to use the documented order of arguments.` — AbraCadaver, Feb 10 '15 at 19:48
I'm sure if you echo what that regex evaluates to, you will have a good idea where the problem lies. — Dan, Feb 10 '15 at 19:50
It's a HTML page code (`file_get_contents('extract/index.html')`). — , Feb 10 '15 at 19:56
Is `file_get_html` is a official PHP function? I do not find any doc on it. — , Feb 10 '15 at 20:06
`file_get_html()` is not a PHP built in function. @Opentuned http://stackoverflow.com/q/14962359/ - http://stackoverflow.com/a/14970732/ <= custom function. — Funk Forty Niner, Feb 10 '15 at 20:11
Apologies, I misread another article, this has a few suggestions: http://htmlparsing.com/php — Opentuned, Feb 10 '15 at 20:16

score 1 · Accepted Answer · answered Feb 10 '15 at 20:13

If one of the bad words is '/w', it can cause this problem. The example below demonstrates this:

$html = 'foobar';

// Bad words checker
$badWords = array("iframe", "alert", '/w');
$matches = array();
$matchFound = preg_match_all("/\b(" . implode($badWords,"|") . ")\b/i", $html, $matches);

Variations of '/w' such as 'foo/wbar' or '/wfoo' would also cause this issue. Go through the badWords and remove the problematic ones.

Edit: Another solution is to use a different delimiter like #. Like this:

$matchFound = preg_match_all("#\b(" . implode($badWords,"|") . ")\b#i", $html, $matches);

You get it! I will accept your answer in few moments! Thanks! — , Feb 10 '15 at 20:20

Error during a preg_match_all in PHP

1 Answers1