Learning more about preg_*, eregi_*

[The Red Guy]

Hi

Can someone recommend some online resources to learn the above mentioned php functions? I read the php manual about the two and found it too advanced for me, with all the slashes and wildcards. Is there any tutorial which breaks down everything step by step? Thanks!

[The New Guy]

Try this
http://www.zend.com/zend/tut/tutorial-delin2.php

[The Red Guy]

Thanks for the resource, that was very kind of you! However all the article did was to introduce preg_match, are there some which teaches *_replace? I know I can use the concepts, but I'm still unclear about things such as []. Are they seperators like ()?

[Technosailor]

What you should know (and where you should begin your searching) is tha preg_* functions use Perl Compatible Regular Expressions (aka PCRE) and the ereg_* functions use POSIX functions. Reality is you should really only concern yourself with PCRE's because, aside from Apache 1.3, everything else pretty much uses PCRE. [url=http://regexlib.com/]Here[/url is a resource you should bookmark. It is geared toward DOT-NET, but DOT-NET uses PCRE as well so syntax is identical.

Now how to use the actual preg_* functions? This is something you will look at php.net for.

Say you have a preg_match.

preg_match('#\[some text](.+)\[goes here]#i',$text); 

That will hypothetically match:

1. Some Text about me goes here.
2. Some text describing ridiculous matters of life and death goes here
3. SoMe TeXt make me go blah goes hERE too

But not just:

Some text goes here.

Now say you wanted to search a whole paragraph for a single phrase and echo it into a string. You'd use preg_replace because you are replacing the whole block of text with something else.

$snippet = preg_replace('#\[some text](.+)\[goes here]#i',"$1",$paragraph); 

Now:

There's plenty of things to consider. Really, the bottom line is that the decision isn't yours to make. You may want some text that you feel goes here to reflect those sentiments.

Becomes:

that you feel

By using $1, in the replace area, I am saying that I want to take the first matched grouping (which was the (.+)).

It's all very complex and you'll have to read about it, but that's a brief overview...

Aaron

[Jeff Lange]

MySQL uses POSIX too .

[Technosailor]

Point well taken.

[The Red Guy]

Alright thanks, (I do not wish to start another thread), can someone point me to a resource which teaches on JOINS in mysql? I've learnt the basics, I need something more in dept.

[Technosailor]

you should start another thread