messing up $line?

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

Let's say I have this


my $line = $_;

if($line =~ s/^.+\/\.(.*)$/$1/)
 { print ". extension ".$line."\n"; }
elsif ( $line =~ s/^.+\.(.*)$/$1/)
 { print "Extension ".$line."\n"; }
[download]

Now then, does $line end up altered after the first if so that the 2nd if is less effective?

Comment on messing up $line? Download Code

Replies are listed 'Best First'.
Re: messing up $line? by chromatic (Archbishop) on Apr 27, 2007 at 17:19 UTC
No; the conditions are exclusive.	[reply]
Re^2: messing up $line? by perlNinny (Beadle) on Apr 27, 2007 at 20:26 UTC
So line doesn't change because the first check is more limited than the second and the substitution isn't fired if it doesn't match. COOL	[reply]
Re: messing up $line? by jettero (Monsignor) on Apr 27, 2007 at 17:17 UTC
I would say the second if (er, elsif in this case) isn't going to fire if the first if actually does a replacement. So no... If they were separate if statements, then yes (possibly). I don't believe the string is ever altered unless an actual replacement happens. -Paul	[reply]
Re: messing up $line? by johngg (Canon) on Apr 27, 2007 at 20:36 UTC
Minor code point, to save yourself some typing take advantage of variable interpolation inside double-quoted strings. `my $line = $_; if($line =~ s/^.+\/\.(.)$/$1/) { print ". extension $line\n"; } elsif ( $line =~ s/^.+\.(.)$/$1/) { print "Extension $line\n"; }` [download] Note that no interpolation takes place inside single-quoted strings. Cheers, JohnGG	[reply] [d/l]
Re: messing up $line? by cengineer (Pilgrim) on Apr 27, 2007 at 17:18 UTC
You're just testing for a match. $line is not being altered.	[reply]
Re^2: messing up $line? by cengineer (Pilgrim) on Apr 27, 2007 at 17:20 UTC
I take that back. I missed the s/	[reply]