More Regular Expressions

Anon

I am trying to learn regular expressions, as it is helping me implement UBBcode in my forum I have built. I have successfully done simple str_replace for to make it and stuff like that, but, to make it easier I would like to search for chunks of messages that start with and end with and make it the HTML bold, for example, as then it would be one statement rather than two... I can't seem to figure that out...can somebody help?

Anon

OK, the forum took my HTML code literally apparantly, but what I am trying to do should have still been understandable. maybe?

van__

preg_replace allows arrays to match multiple items.

$text = preg_replace(array('/[b]/','/[\/b]/'),array('',''),$text);

van__

haha...
I forgot to use the html chars for those bold tags.

Just enter in the open and close tags in their respective spots in the replacement array.

Anon

Oh, that works great! Now, if a may be so bold, one more issue I am trying to do in relation to this UBBcode as well, I want to make a size thing so would make the font size "4" how can I find that in one statement so I don't have to look for , , etc. so that can be turned into an HTML font tag and closing font tag?

Any more I am trying to learn more about these regular expressions as it seems they can be quite powerful...if I can learn this one last thing by example, I think I will have a great base to grow on, thansk for your help...these forums are awesome!

van__

Pretty basic with the use of backreferencing.

<?
$text = "some text here";
$text = preg_replace('/[(size=+[0-9]{1})](.*[^{[]+)[\/size]/is',"</font} \1>\2",$text);
echo $text;
?>

read up in the manual, they have some pretty good examples of usage.
http://www.php.net/manual/en/ref.pcre.php

van__

woops, that replacement string has a closing font tag instead of an open tag...

<?
$text = "some text here";
$text = preg_replace('/[(size=+[0-9]{1})](.*[^{[]+)[\/size]/is',"<font} \1>\2",$text);
echo $text;
?>

...all fixed.
You probably would have fig'd it out anyway.

Anon

Thanks, that is pretty much what I expected to see...I just didn't know how to get the data out and save it to put back in, so whatever is in parenthases is the \1 and \2 in the order they are found in the expression...is that right?

Thnaks, this is getting a little les funfusing all the time, I read a bit on php.net and the article here about regex and some things I just can't get without doing them I guess...thanks again!

Anon

Lastly (hopefully:-) is there a way to keep the integer input to a 1-7? because 0, 8 and 9 are invalid HTML syntax anyway...

not necessary, ya just got me curious now 🙂

van__

yes...
just change from [0-9] to [1-7]

and you're right on about the use of parenthesis. They create memory called a "backreference" that allows you to extract key portions and play with them.

They are also handy for preg_match() where you can store them all to a 2D array for use throughout your code.

If you just play with different patterns to match, you'll get the hang of it. Better to go through the agony and learn than rely on free help, since regex is very powerful when used correctly.

Anon

I figured that was it, the 1-7 thing...I suppose I could tried it before asking :-) thanks for all your help, this is great stuff to know!