PERL Beginners - Problem using "my" to protect scope

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Author

Problem using "my" to protect scope

careybunks@gmail.com

2005-07-24, 8:29 pm

Hi All,

I've written a program that passes an array of arrays (a very simple
one) to a subroutine. In the sub, a locally scoped copy is made using
"my". However, changing the value of the copy in the sub also changes
the value in the calling program. I thought this wasn't supposed to
happen. Can anyone help me explain why?

Here is the program:

-------------------------------------------------------------

#!/usr/bin/perl -w

@p = ([1, 7]);
print "@{$p[0]}\n";
modval(@p);
print "@{$p[0]}\n";

sub modval {
my @p = @_;

$p[0]->[0]++;
}

-------------------------------------------------------------

I'm expecting the output of the program to be:

1 7
1 7

But what I get is:

1 7
2 7

Any ideas?

Thanks,

CB

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