What's a foolproof method to allow code posting?

[Prismatic]

Working on my forums again and I need a foolproof method of getting code (any kind, if it's code, it can go) transformed into a safe version to be processed and regurgatated back when someone views a post.

For instance, I have a [bbcode][/bbcode] tag on my forums which, when you use it, produces a code block very similar to the forums here currently (Actually identical, I really liked your code blocks  :P ). I need a way to make all code "safe" in that it wont be run when I want to show it back, it also has to be able to pass through preg_replace without causing any errors (it likes to fail evaluation on some characters)

Any help is appreciated :)

[kenrbnsn]

Use the function htmlentities() on any string you display back to the screen.

What do mean by:
[quote]t also has to be able to pass through preg_replace without causing any errors (it likes to fail evaluation on some characters)[/quote]

Ken

[Daniel0]

[quote author=kenrbnsn link=topic=99929.msg393836#msg393836 date=1152416357]
What do mean by:
[quote]t also has to be able to pass through preg_replace without causing any errors (it likes to fail evaluation on some characters)[/quote]
[/quote]

I think he is using it for his BBCodes.

Here is an example of the [b]bold[/b], [i]italic[/i] and [u]underline[/u] BBCodes: [code]$t = preg_replace("`\[b\](.*)\[/b\]`sUi","<b>\\1</b>",$t);
$t = preg_replace("`\[i\](.*)\[/i\]`sUi","<i>\\1</i>",$t);
$t = preg_replace("`\[u\](.*)\[/u\]`sUi","<u>\\1</u>",$t);[/code]

[Prismatic]

I dont need all BB codes, I already have those done. I mean accepting php, html, all those kinds of code and processing them so I can safely store them in the database without the fear of them getting run and causing issues.

[Daniel0]

Ahh, just run the through htmlentities() as Ken said ;)

[kenrbnsn]

Also, always process all text with mysql_real_escape_string() when inserting/updating the text into the database.

Ken