regexp help

iBuddy

<td class="lName" colspan=2 width="100%">

									DESERT FOOTHILLS MECHANICAL
								</td>

The reg exp I am using is not working....I think it's because there is so much white space?

<td class=\"lName\" colspan=2 width=\"100%\">(.*)<\/td>

Anyone notice what is wrong with my regexp?

wilku

< and > are metacharacters as well and therfore must be escaped as well. Double quote on the other hand isn't so unless you write your regex inside double quotes, don't escape them:

$regex = '\<td class="lName" colspan=2 width="100%"\>(.*)\<\/td\>';

I didn't check if it actually works.

suntra

Actually "<" and ">" are NOT special characters, and you need to add the s modifier after your pattern...

ALSO, add a question mark after ".*". This way, PREG will stop at the closet </td> found...

$strREGEX = '#<td class="lName" colspan=2 width="100%">(.*?)</td>#s';

http://ca3.php.net/manual/en/reference.pcre.pattern.modifiers.php

s (PCRE_DOTALL)
If this modifier is set, a dot metacharacter in the pattern matches all characters, including newlines. Without it, newlines are excluded. This modifier is equivalent to Perl's /s modifier. A negative class such as [^a] always matches a newline character, independent of the setting of this modifier.

wilku

Oh, yeah, I've forgotten about newlines 🙂
As for < and >, I checked in google and it they aren't indeed mentioned as metacharacters. Nevertheless, check out this cheat sheet I got somewhere from the net - < and > are listed as needed to be escaped. Does that mean this cheat sheet is bull sh*t instead?

http://www.ilovejackdaniels.com/cheat-sheets/regular-expressions-cheat-sheet/

NogDog

Well, that cheat sheet contradicts itself in that at the top left it shows < and > as being "anchors", then at the bottom right shows them being "escaped" as literal characters for HTML tags.

The only special use of either of them that I can think of in PCRE regexp's in PHP is in look-behind assertions and named sub-patterns. In those cases, the position in relation to other characters determines if they are being used for those special purposes.

That being said, it doesn't particularly hurt to escape them if you think there could be any ambiguity/confusion, but in most cases it won't be necessary. And you can always let PHP do the work by using the [man]preg_quote[/man] function to escape characters used in string literals:

$search = "a bunch of text with lots of characters: <>.,/^!@#";
if(preg_match('/'.preg_quote($search).'/i', $text)) {