[Resolved] Regular Expressions Help

Silverlime

I am trying to remove tags from a string of HTML in the following format:

if{ranks}This is the ranking system!endif{ranks}

Now, in that scenario I would want to remove everything between if{ranks} and endif{ranks}, including the tags themselves. If I have multiple tags, however, it gets tricker. Here's an example:

if{games}games1endif{games}Testing this!if{games}endif{games}

If I wanted to remove everything between the if{games} and endif{games} tags, but not what's in between. What is a regular expression which will not jump to the end and take everything from the first if{games} and the second endif{games} out - leaving nothing in the middle?

I have the following right now:

$template = ereg_replace('if{' . $statement . '}+(.*)+endif{' . $statement . '}','',$template);

But that removes everything between the two farthest tags. Thanks for your help!

shavas

I have had this exact same proiblem. And after going though the dam manual and reading up on it i got an explanasion on the error. By default regular excpressions are greedy in matching their stuff. So it will go though the document and match it 2 it cant match it any more. Thus it goes to the very end and takes out everything inbetween you start clause and end clause(last match).

By default, the quantifiers are "greedy", that is, they
match as much as possible (up to the maximum number of permitted
times), without causing the rest of the pattern to
fail. The classic example of where this gives problems is in
trying to match comments in C programs. These appear between
the sequences / and / and within the sequence, individual
* and / characters may appear. An attempt to match C comments
by applying the pattern

   /\*.*\*/

 to the string

   /* first command */  not comment  /* second comment */

 fails, because it matches  the  entire  string  due  to  the
 greediness of the .*  item.

 However, if a quantifier is followed  by  a  question  mark,
 then it ceases to be greedy, and instead matches the minimum
 number of times possible, so the pattern

   /\*.*?\*/

 does the right thing with the C comments. The meaning of the
 various  quantifiers is not otherwise changed, just the preferred
 number of matches.  [/I]

That is fromt he manual.
Now the problem i had was this just spat out errors for me. But their is the section from PHP manual. Find it and read up might work for u

Silverlime

I just get

Warning: ereg_replace() [function.ereg-replace]: REG_BADRPT

using that system but I will keep working at it.

shavas

That is the exact same dam thing i got. Dont know wether manual is wrong or you just haev to switch something else on. But as u can see they manual cearly defines the problem, just their solution doesnt seem to work.

Hope somone else has a way to actually to implement the manuals command

Weedpacket

I think it's because ereg_replace doesn't do ungreedy matching - which means that it has no idea what "*?" is supposed to mean.

preg_replace() is faster and has a more powerful (if slightly less straightforward) syntax (and there is some documentation in the PHP manual, instead of having it assume that you can just man 7 regex to find out the syntax for ereg's expressions.

For preg_replace(), the regexp is

#/\*.*?\*/#

(Look familiar? The only difference is that preg_*() regexps need a character at the start and end of the regexp to show where it starts and ends. That's because it can be followed by various letters that alter the regexp's behaviour.)

There's a deeper problem to Silverlime's situation - let's put it this way: there's a reason why HTML closing tags are different from opening tags.

Silverlime

There's a deeper problem to Silverlime's situation - let's put it this way: there's a reason why HTML closing tags are different from opening tags.

If you look closely, my tags are also different 🙂 And my problem is solved now, thanks a lot!