s///g and capturing all matches

[Random_Walk]

good $localtime fellow monks,

I am tearing my hair out over a small oddity. Why will this work:

perl -nle "my (@c) = /\:(\w+)\:/g; print join '.', @c"
 input> out:caputure1:out:capture2:out
output> caputure1.capture2

But this behaves so differently

perl -nle "my (@c) = s/\:(\w+)\:/X/g; print join '.', @c"
 input> out:caputure1:out:capture2:out
output> 2

I am trying to extract comments from a file I have in a buffer read in with local $/;. The comments are marked by a ; and continue to the end of the line. For various reasons I want the file as a sinlge line and want to extract the comments. The comments will be added back in later so I substiture them for a marker. I realise I could break the file into lines and put it back together again later but I would love to be able to do it in one line

Cheers,
R.

[johngg]

Rather than a global match you could use a while statement modifier.

knoppix@Microknoppix:~$ perl -E '
> $file = <<EOD;
> some data; comment 1
> more data; comment 2
> even more data; comment 3
> EOD
> push @comments, $1 while $file =~ s{(;[^\n]*)}{*MARKER*};
> say $file;
> say for @comments;'
some data*MARKER*
more data*MARKER*
even more data*MARKER*

; comment 1
; comment 2
; comment 3
knoppix@Microknoppix:~$ 

I hope this is of interest.

[Random_Walk]

Hi JohnGG,

I had tried the while but could not get the syntax right. Thanks for pointing me down the right path.

Cheers,
R.

[Anonymous Monk]

:D Because m// and s/// are different operators that behave differently :D

s/// always returns the number of matches, unless you use /r, in which case it returns a string copy see perlop#s/PATTERN/REPLACEMENT/msixpodualgcer

my @c;
s/(...)/ push @c, $1; q[X]; /ge

[Random_Walk]

thank you anonymonk, very ellegant. I had forgoton the use of code in the RHS was possible.

Cheers,
R.

[jethro]

To quote the documentation of s/// it " returns the number of substitutions made". You made two substitutions, so the result is 2

[Random_Walk]

Hi Jethro,

and the answer to life, the universe and everything is 42 ;)

I was wondering why the implementations differ, as well as seeking an ellegant way to get the behaviour I wanted. If s///; returned a list of the items sub'd out then it would be easy enough to use that in scalar contect to have the number. Felt rather un-Perlish to miss out on potential utility.

Cheers,
R.