"Its Late & I Cant Spot The Error

[CrYpTiC_MauleR]

<?php 

preg_match("/\x5C([^\x5C]+)\.txt\n(\d{2,3})\n([\d:]{8})/", $data, $match);

?>

is causing the following error "Warning: preg_match(): Compilation failed: unmatched parentheses at offset 33"
But I seem to be blind and can't find whats wrong with it.

[GrandSchtroumpf]

how about changing the double quotes to single quotes... or using double escaping?

[CrYpTiC_MauleR]

double quotes should work though, also double escaping and just using hex value should be the same. Why does it errors about an unclosed parentheses...weird. I'll try your suggestion, but if it works I will be even more confused.

preg_match('/\x5C([^\x5C]+)\.mp3\n(\d{2,3})\n([\d:]{8})/', $data, $match);

that worked, but why?

[GrandSchtroumpf]

It's only a matter of correctly escaping your characters and correctly using PHP's automatic string evaluation (string declarations with 'double quotes')...
I always use single quotes when defining regexps, it's much safer.


Here is a little test i wrote to illustrate the differences:

Code

Language: php (GeSHi-highlighted)
<?php 
 
$data = '
\\dummy.txt
664
05:42:18
';
 
echo "<pre>
 
 
";
 
echo "data = $data <br>";
 
 
Echo '
<h2>PATTERN 1</h2>';
 
 
$pattern = '/\\\\([^\\\\]+)\\.txt\\n(\\d{2,3})\\n([\\d:]{8})/';
 
echo "\n\n<b>pattern 1 = $pattern</b>";
preg_match($pattern, $data, $match);
echo "\n\nmatch = ". $match[0];
echo "<blockquote>
This is the pattern with all backslashes escaped, to remove all ambiguities.
In this case, we can replace the 'single quotes' with 'double quotes' and the string remains identical.
To match a backslash character, the pattern uses an escaped backslash.
This means quadruple backslash in the string declaration.
Here, the pattern uses 'backslash-n' to match a new line.
</blockquote>";
 
 
$pattern = "/\x5C\x5C([^\x5C\x5C]+)\.txt\x5Cn(\x5Cd{2,3})\x5Cn([\x5Cd:]{8})/";
 
echo "\n\n<b>pattern 1 = $pattern</b>";
preg_match($pattern, $data, $match);
echo "\n\nmatch = ". $match[0];
echo "<blockquote>
This is exactly the same pattern but using 'double quotes' and 'hex values' in the string declaration.
</blockquote>
";
 
 
Echo '
<h2>PATTERN 2</h2>';
 
 
$pattern = '/\x5C([^\x5C]+)\\.txt\\n(\\d{2,3})\\n([\\d:]{8})/';
 
echo "\n\n<b>pattern 2 = $pattern</b>";
preg_match($pattern, $data, $match);
echo "\n\nmatch = ". $match[0];
echo "<blockquote>
This is a different pattern.
It uses the 'hex value' to match the backslash character instead of using an escaped backslash.
</blockquote>";
 
 
Echo '
<h2>PATTERN 3</h2>';
 
$pattern = "/\\\\([^\\\\]+)\\.txt\n(\\d{2,3})\n([\\d:]{8})/";
 
echo "\n\n<b>pattern 3 = $pattern</b>";
preg_match($pattern, $data, $match);
echo "\n\nmatch = ". $match[0];
echo "<blockquote>
This is yet a different pattern.
It uses the 'line-feed' character to match a new line instead of using a 'backslash-n'.
</blockquote>";
 
 
echo "
 
 
</pre>";
 
?>

Here is a summary of the code here-above:

Code

Language: php (GeSHi-highlighted)
$pattern = '/\\\\([^\\\\]+)\\.txt\\n(\\d{2,3})\\n([\\d:]{8})/';
$pattern = "/\x5C\x5C([^\x5C\x5C]+)\.txt\x5Cn(\x5Cd{2,3})\x5Cn([\x5Cd:]{8})/";
$pattern = '/\x5C([^\x5C]+)\\.txt\\n(\\d{2,3})\\n([\\d:]{8})/';
$pattern = "/\\\\([^\\\\]+)\\.txt\n(\\d{2,3})\n([\\d:]{8})/";

[VGR]

arf arf arf regexps :D

[GrandSchtroumpf]

Actually, to be consistant, i should have escaped all the backslashes in the third pattern declaration:

Code

Language: php (GeSHi-highlighted)
$pattern = '/\\x5C([^\\x5C]+)\\.txt\\n(\\d{2,3})\\n([\\d:]{8})/';

This way it should not matter if we use single or double quotes.

Regexps are great... when used appropriately.

IMHO, the most confusing part is how PHP automatically escapes backslashes.  Java does not do that, so you end up with a lot more backslashes in you string declarations, but at least you make less mistakes.

[VGR]

il y a deux options magic_quotes dans php.ini