Preg_match help

[mifflin]

can someone explain a few things for me?  and yes I googled it, but I just had a few questions. 

 

In preg_match, "(.+?)" could be basically anything, "/^" means no slash, but what does "\|\|\|/" mean? slash or slash or slash or forward slash?  I'm not getting what this does....  look.

 

[pre]

preg_match("/^(.+?)\|\|\|/", $obj->images, $matches);

if (!isset($matches[1])) {

preg_match("/^(.+?)\|(.+?)\|\|/", $obj->images, $matches);

$img = $matches[1];

$img_align = $matches[2];

[/pre]

 

 

and, I know this is a dumb question, but what does the " $obj->images, $matches);" do after the preg_match

 

 

Thanks in advance. 

[nrg_alpha]

No, you misunderstand..

 

(.+?) - the dot is a wildcard that matches a single character (other than a newline  by default). the + is a one or more times quantifier, and the ? makes the + lazy (it will not be greedy) The parenthesis that encases this all is a capture, which means whatever it matches in .+? will be stored into the value $1.

 

/^ The / is actually the beginning delimiter (you'll notice that the pattern starts and ends with /.. so after the opening delimiter, the ^ means from the start of the string.

 

\|\|\| is a way of saying, match 3 consecutive pipes... which could be re-wirtten as \|{3}.. the backslash escapes the pipe character so that the pattern doesn't see it as OR, as the pipe is used for such purposes, as in (ab|bc) which would mean, capture the letters ab OR bc.

 

As far as $obj->images is concerned, this is an object containing a property called images (google OOP - Object Oriented Programming).

The $matches means what ever the pattern matches, it will be stored into the array called, well, $matches. The complete pattern would be stored as $matches[0]. So if there is parenthesis involved, the first set will be stored into $matches[1], if there is a second set of parenthesis, this will be stored into $matches[2], etc.. (which runs in parellel with $1, $2, etc.. (hope I'm clear in my explanations here).

 

You can have a look at these regex resources to better understand what's going on:

 

http://www.regular-expressions.info/

http://weblogtoolscollection.com/regex/regex.php

http://www.amazon.com/Mastering-Regular-Expressions-Jeffrey-Friedl/dp/0596528124/ref=pd_bbs_sr_1?ie=UTF8&s=books&qid=1239475391&sr=8-1

pcre

http://www.phpfreaks.com/forums/index.php/topic,127902.0.html

http://www.phpfreaks.com/tutorial/regular-expressions-part1---basic-syntax

 

This will be more than enough to get you started.