Range out of order in character class - php

Question

I'm getting this odd error in the preg_match() function:
Warning: preg_match(): Compilation failed: range out of order in character class at offset 54
The line which is causing this is:
preg_match("/<!--GSM\sPER\sNUMBER\s-\s$gsmNumber\s-\sSTART-->(.*)<!--GSM\sPER\sNUMBER\s-\s$gsmNumber\s-\sEND-->/s", $fileData, $matches);
What this regular expression does is parse an HTML file, extracting only the part between:
<!--GSM PER NUMBER - 5550101 - START-->
and:
<!--GSM PER NUMBER - 5550101 - END-->
Do you have a hint about what could be causing this error?

Answer 1

Hi I got the same error and solved it:
Warning: preg_match(): Compilation failed: range out of order in character class at offset <N>
Research Phase:
.. Range out of order .. So there is a range defined which can't be used.
.. at offset N .. I had a quick look at my regex pattern. Position N was the "-". It's used to define ranges like "a-z" or "0-9" etc.
Solution
I simply escaped the "-".
\-
Now it is interpreted as the character "-" and not as range!

Answer 2

If $gsmNumber contains a square bracket, backslash or various other special characters it might trigger this error. If that's possible, you might want to validate that to make sure it actually is a number before this point.
Edit 2016:
There exists a PHP function that can escape special characters inside regular expressions: preg_quote().
Use it like this:
preg_match(
'/<!--GSM\sPER\sNUMBER\s-\s' .
preg_quote($gsmNumber, '/') . '\s-\sSTART-->(.*)<!--GSM\sPER\sNUMBER\s-\s' .
preg_quote($gsmNumber, '/') . '\s-\sEND-->/s', $fileData, $matches);
Obviously in this case because you've used the same string twice you could assign the quoted version to a variable first and re-use that.

Answer 3

This error is caused for an incorrect range. For example: 9-0 a-Z
To correct this, you must change 9-0 to 0-9 and a-Z to a-zA-Z
In your case you are not escaping the character "-", and then, preg_match try to parse the regex and fail with an incorrect range.
Escape the "-" and it must solve your problem.

Answer 4

I was receiving this error with the following sequence:
[/-.]
Simply moving the . to the beginning fixed the problem:
[./-]

Answer 5

While the other answers are correct, I'm surprised to see that no-one has suggested escaping the variable with preg_quote() before using it in a regex. So if you're looking to match an actual bracket or anything else that means something in regex, that'll be converted to a literal token:
$escaped = preg_quote($gsmNumber);
preg_match( '/<!--GSM\sPER\sNUMBER\s-\s'.$escaped.'\s-\sSTART-->(.*)<!--GSM\sPER\sNUMBER\s-\s'.$escaped.'\s-\sEND-->/s', $fileData, $matches);

Answer 6

You probably have people insert mobile numbers including +, -, ( and/or ) characters and just use these as is in your preg_match, so you might want to sanitize the data provided before using it (ie. by stripping these characters out completely).

Answer 7

This is a bug in several versions of PHP, as I have just verified for the current 5.3.5 version, as packaged with XAMPP 1.7.4 on Windows XP home edition.
Even some very simple examples exhibit the problem, e.g.,
$pattern = '/^[\w_-. ]+$/';
$uid = 'guest';
if (preg_match($pattern, $uid)) echo
("<style> p { text-decoration:line-through } </style>");
The PHP folks have known about the bug since 1/10/2010.
See http://pear.php.net/bugs/bug.php?id=18182.
The bug is marked "closed" yet persists.