preg_match acting very strange

Question

I am using preg_match() to extract pieces of text from a variable, and let's say the variable looks like this:

[htmlcode]This is supposed to be displayed[/htmlcode]

middle text

[htmlcode]This is also supposed to be displayed[/htmlcode]

i want to extract the contents of the [htmlcode]'s and input them into an array. i am doing this by using preg_match().

preg_match('/\[htmlcode\]([^\"]*)\[\/htmlcode\]/ms', $text, $matches);
foreach($matches as $value){
return $value . "<br />";
}

The above code outputs

[htmlcode]This is supposed to be displayed[/htmlcode]middle text[htmlcode]This is also supposed to be displayed[/htmlcode]

instead of

[htmlcode]This is supposed to be displayed[/htmlcode]
[htmlcode]This is also supposed to be displayed[/htmlcode]

and if have offically run out of ideas

@hjpotter92 good point, however the problem is in the regex, rather than the PHP function used. — Stefano Sanfilippo, May 09 '13 at 23:25
@hjpotter92 ah, sorry :P been trying to solve this all day, been working with preg_match and preg_replace and its now very late so my brain is a little confused :P Edited — Simon Andersson, May 09 '13 at 23:25
Everyone is saying add a `?` which is true but you could also use the `U` modifier, note that it's a capital letter. — HamZa, May 09 '13 at 23:30

score 3 · Answer 1 · answered May 09 '13 at 23:22

3

A * grouper is greedy, i.e. it will eat everything until last [/htmlcode]. Try replacing * with non-greedy *?.

answered May 09 '13 at 23:22

Stefano Sanfilippo

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score 3 · Accepted Answer · answered May 09 '13 at 23:27

As explained already; the * pattern is greedy. Another thing is to use preg_match_all() function. It'll return you a multi-dimension array of matched content.

preg_match_all('#\[htmlcode\]([^\"]*?)\[/htmlcode\]#ms', $text, $matches);
foreach( $matches[1] as $value ) {

And you'll get this: http://codepad.viper-7.com/z2GuSd

score 2 · Answer 3 · edited May 23 '17 at 12:29

2

* is by default greedy, ([^\"]*?) (notice the added ?) should make it lazy.

What do lazy and greedy mean in the context of regular expressions?

edited May 23 '17 at 12:29

Community

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answered May 09 '13 at 23:22

kapa

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score 2 · Answer 4 · answered May 09 '13 at 23:22

Look at this piece of code:

preg_match('/\[htmlcode\]([^\"]*)\[\/htmlcode\]/ms', $text, $matches);
foreach($matches as $value){
return $value . "<br />";
}

Now, if your pattern works fine and all is ok, you should know:

return statement will break all loops and will exit the function.
The first element in matches is the whole match, the whole string. In your case $text

So, what you did is returned the first big string and exited the function.

I suggest you can check for desired results:

$matches[1] and $matches[2]

preg_match acting very strange

4 Answers4