regexing my brain...

Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

i've got the source code from an html document read into $pagecode, and the code should replace a portion surrounded by special comment tags with $content, after which the source is written back to the html document. now, when i run the script for some reason, nothing is changed between the comment tags...any idea why?

$pagecode =~ s/<!--BeginContent-->(.*)<!--EndContent-->/<!--BeginConte
+nt-->$content<!--EndContent-->/;
$pagecode =~ s/<!--BeginPages-->(.*)<!--EndPages-->/<!--BeginPages--><
+!--EndPages-->/;
[download]

Comment on regexing my brain... Download Code

Replies are listed 'Best First'.
Re: regexing my brain... by ysth (Canon) on Nov 17, 2003 at 03:59 UTC
Just a guess - do you need to add the s flag (e.g. s/foo/bar/s;) so that (.*) will include newline characters?	[reply]
Re: Re: regexing my brain... by Anonymous Monk on Nov 17, 2003 at 04:05 UTC
YES!!!! thankyouthankyouthankyouthankyouthankyouthankyouthankyou!!!	[reply]
Re: regexing my brain... by sgifford (Prior) on Nov 17, 2003 at 08:16 UTC
Something else to keep in mind is that `.*` is greedy, so if you have: `<!--BeginContent-->Content 1 Here<!--EndContent--> <!--BeginContent-->Content 2 Here<!--EndContent-->` [download] it will match all of it, not just the first one. Especially when you're doing multi-line matching, that can bite you sometimes.	[reply] [d/l] [select]
Re: regexing my brain... by BUU (Prior) on Nov 17, 2003 at 04:07 UTC
Omg. Use HTML::Template now. NOW!	[reply]
Re: regexing my brain... by Roger (Parson) on Nov 17, 2003 at 04:15 UTC
I suspect that the text you want to replace contains '\n' characters. I have created the following code to inspect your code - #!/usr/local/bin/perl -w use strict; my $pagecode; { local $/; $pagecode = <DATA>; } my $content = "Roger"; print "before:\n---------\n$pagecode\n"; # fix 1 $pagecode =~ s/<!--BeginContent-->(?:.\|\n)<!--EndContent-->/<!--Begin +Content-->$content<!--EndContent-->/; # fix 2 $pagecode =~ s/<!--BeginPages-->.<!--EndPages-->/<!--BeginPages--><!- +-EndPages-->/s; print "after:\n---------\n$pagecode\n"; __DATA__ <!--BeginContent-->Hello World! This is a comment line <!--EndContent--> <!--BeginPages-->Hello World! <!--EndPages--> [download] Note that there are many ways to fix this problem. By the way, you can drop the capture ( .. ) in your regexp too. The first method - replace `(.)` in your regexp with `(?:.\|\n)`. The second method - add the 's' switch at the end of the regexp.	[reply] [d/l] [select]