shift @ARGV not working

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

Quick one here. If called as script.pl -s, why doesn't this print "-s"?

#!/usr/bin/perl
if ($ARGV[0] eq '-s') {
   my $argument = shift @ARGV;
}
print "$argument";
[download]

I know the comparison is true but the shift doesn't seem happy. If I type "print shift @ARGV", I can see the -s. However it doesn't want to be assigned to a variable.

Comment on shift @ARGV not working Download Code

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Re: shift @ARGV not working by toolic (Bishop) on May 09, 2013 at 18:44 UTC
Variables and Scoping: `#!/usr/bin/perl my $argument; if ($ARGV[0] eq '-s') { $argument = shift @ARGV; } print "$argument";` [download] Tip #1 from the Basic debugging checklist: use strict and warnings	[reply] [d/l]
Re^2: shift @ARGV not working by rayh (Initiate) on May 09, 2013 at 18:58 UTC
Derp. Duh. I was getting a little too fancy in a larger script and overlooked the use of "my" in a new block. Thanks!	[reply]
Re: shift @ARGV not working by blue_cowdawg (Monsignor) on May 09, 2013 at 18:47 UTC
`#!/usr/bin/perl -w use strict; foreach my $i(0..$#ARGV){ printf "\$ARGV[%d] = \"%s\"\n",$i,$ARGV[$i]; } while(my $arg=shift @ARGV){ printf "%s\n",$arg; } # # -------------- 8< snip! 8<------------- $ ./shifty.pl a b c d e f g $ARGV[0] = "a" $ARGV[1] = "b" $ARGV[2] = "c" $ARGV[3] = "d" $ARGV[4] = "e" $ARGV[5] = "f" $ARGV[6] = "g" a b c d e f g` [download] I think the issue you are a having is you didn't shift prior to setting $argument. Peter L. Berghold -- Unix Professional Peter -at- Berghold -dot- Net; AOL IM redcowdawg Yahoo IM: blue_cowdawg	[reply] [d/l]
Re^2: shift @ARGV not working by Anonymous Monk on May 09, 2013 at 19:15 UTC
Howdy blue_cowdawg, How could you miss that? The issue he was having is variable scope issue. How does the OP think he would be able to print the variable, when it was scoped to the if block? Moreover, if the OP has used strict and warnings, he would have seen the red gauge I think you need a break from the keyboard. You are working to hard...	[reply]
Re^3: shift @ARGV not working by Anonymous Monk on Apr 04, 2024 at 13:13 UTC
Also, the OP did "`shift` before setting `$argument`", because the assignment is processed from right to left.	[reply] [d/l] [select]