php function preg_replace regex not working, a syntax question

Question

im trying to remove unnessary comments with preg-replace in controlled script situations, but my regex is incorrect. Anyone any ideas whats wrong with my regex? (i have Apache/2.0.54 & PHP/5.2.9

BEFORE:

// Bla Bli Blue Blow Bell Billy Bow Bye
script var etc ();    // cangaroo cognac codified cilly celine cocktail couplet
script http://blaa.org    // you get the idea!

AFTER:

script var etc ();
script http://blaa.org

PROBLEM: what regex to use?

# when comment starts on a new line, delete this entire line
# find [a new line] [//] [space or no space] [comment]
$buffer = preg_replace('??', '??', $buffer);

# when comment is halfway in script (    //  comment)
# find [not beginning of a line] [1 TAB] [//] [1 space again] [comment]
$buffer = preg_replace('??', '??', $buffer);

Any and All suggestions will be valued +1 by me, cuase im so darn close to solve this riddle!

Have you considered using a proper tokenizer instead of a regex? You will be able to throw out only the comment tokens. — cdhowie
– cdhowie, Commented Dec 13, 2010 at 18:42
What about multi-line comments? Especially nested multi-line comments? That's hideously non-trivial for regex, but trivial for a tokenizer /* this is a /* nested comment */ — Marc B
– Marc B, Commented Dec 13, 2010 at 18:46
Writing comments consistently, means there is no room for such a strange thing Marc B, a comment within a commment. Nevertheless ironic that such a lecture on consistency comes from the mouth of a very incapable programmer, namely myself hahah! — Sam
– Sam, Commented Dec 13, 2010 at 21:04
Thanks CDHowie, what is a tokenizer? can you give an example how to use that? I have a general question about this regex thing: does it belong to PHP, to Apache or somethin else? and is a Tokenizer same as Regex but with only different syntax? — Sam
– Sam, Commented Dec 13, 2010 at 21:12

Bart Kiers · Accepted Answer · 2010-12-13 19:37:03Z

1

Try this regex:

/(?<!http:)\/\/[^\r\n]*/

Be cautious though, consider strings like:

<!-- 
// not a comment -->

or

/* 
// not a comment */

and

var s = "also // not // a // comment";

And you might want to work around https://... and ftp://... etc.

edited Dec 13, 2010 at 19:37

answered Dec 13, 2010 at 18:45

Bart Kiers

171k37 gold badges307 silver badges297 bronze badges

# BEAUTIFULL!!!! lacking those strange situations with comments in a comment gives space for even cleaner code: your regex worked first time out of the box! wish you a great weekend Bart!

Sam
– Sam

12/13/2010 21:09:02
Commented Dec 13, 2010 at 21:09
@Sam, you're welcome. Weekend? That will take a few more days, but thanks and you have a nice day too! :)

Bart Kiers
– Bart Kiers

12/14/2010 07:25:03
Commented Dec 14, 2010 at 7:25

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