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Answer: Subroutine args by-value vs. by-ref

by Anonymous Monk
on Aug 24, 2002 at 01:40 UTC ( #192509=categorized answer: print w/replies, xml ) Need Help??

Q&A > subroutines > Subroutine args by-value vs. by-ref - Answer contributed by Anonymous Monk

All your previous experience is confusing you.

Read perldata, perlsyn, perlref and perlsub (if perlsub exists).

There are no pointers in perl, there are only scalar's hashes's and array's, and references. Some might say there are also lists, and they're right.

subroutines get arguments via the magical @_ variable, meaning every time you say Foo(1,2,3), inside of sub Foo, the @_ array will contain 1,2 and 3 as it's value.

That's pass-by-value.

my @Arra = ( 1, 2, 3, 4 ); PassByReference(\@Arra); sub PassByReference { die "@_"; }
Here are some more examples.
use Data::Dumper; DIE(1..10); DIE(1,2,3,4,5,6,,8,9); DIE( [ 1..10 ] ); DIE( { 1..10 } ); my @ARRAY = 1..10; my %HASH = @ARRAY; DIE( @ARRAY ); DIE( %HASH ); DIE( \@ARRAY ); DIE( \%HASH ); DIE( @ARRAY, \%HASH ); DIE( \@ARRAY, \%HASH ); DIE( \@ARRAY, %HASH ); DIE( \&DIE ); ¨ DIE(); sub DIE { print Dumper(@_) };

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