Using text file as pattern preg_match_all PHP

Question

error:preg_match_all(): Compilation failed: nothing to repeat at offset 59

Hello everyone, I am trying to make a word filter for a client and i have ran into the issue that my code witch is pulling words from a text file can not read the $ character from my text file, mycode is below.

 $lines=array();
  $fp=fopen('/opt/lampp/htdocs/Comments/Classes/Bad.txt', 'r');
  while (!feof($fp))
  {
    $line=fgets($fp);
    //process line however you like
    $line=trim($line);
    //add to array
    $lines[] = preg_quote(trim($line));
  }
    fclose($fp);
    $string = Input::get('comments');
    $matches = array();
    $matchFound = preg_match_all(
      "/\b(" . implode("|", $lines) . ")\b/i", 
            $string, 
            $matches
          );
    if ($matchFound) {
      $this->addError("The following is not allowed please change it.");
      $words = array_unique($matches[0]);
      foreach($words as $word) {
        echo "<li>" . $word . "</li>";
      }
      echo "</ul>";
    }

Oswald · Accepted Answer · 2014-08-20 21:54:16Z

2

Use preg_quote on each line while reading in the text file.

answered Aug 20, 2014 at 21:54

Oswald

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Comments

Marc B · Accepted Answer · 2014-08-20 21:55:34Z

0

You're probably inserting text that happen contains regex metacharacters, and inserting them in such a way that they're actually treated as metachars. You need to preg_quote() the text you're inserting to escape all of those metachars.

answered Aug 20, 2014 at 21:55

Marc B

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10 Comments

Charles Over a year ago

So it would would look something like this $line=trim(preg_quote($line));

Marc B Over a year ago

don't manipulate the quoted string in any way once it's been quoted. trim() won't do much, but any other manipulations COULD undo the quoting. trim THEN quote.

Charles Over a year ago

I did the preg_quote after the then and it still isnt searching for the special character i may be doing something wrong i updated the code above

Marc B Over a year ago

You've got preg_quote($lines), and $lines is your array. so you're using an array in string context, and PHP will politely convert that array into the literal word Array. try $lines[] = preg_quote(trim($line)).

Charles Over a year ago

So i echo the array and found that the line isn't $$ in the array it is \$\$ could that be because of my sanitize function htmlentities(string)($string, ENT_QUOTES, 'UTF-8');

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