What is the difference between
myArr1 => \@existingarray
and
myArr2 => [
@existingarray
]
I am assigning the @existingarray to a element in a hash map.
I mean what exactly internally happens. Is it that for the first one, it points to the same array and for the second array it creates a new array with the elements in the @existingarray
Thanks in advance
Yes, the first one takes a reference, the second one does a copy and then takes a reference.
[ ... ] is the anonymous array constructor, and turns the list inside into an arrayref.
So with @a = 1, 2, 3,
[ @a ]
is the same as
[ 1, 2, 3 ]
(the array is flattened to a list) or
do {
my @b = @a;
\@b;
}
In effect, the elements get copied.
Also,
my ($ref1, $ref2) = (\@a, [@a]);
print "$ref1 and $ref2 are " . ($ref1 eq $ref2 ? "equal" : "not equal") . "\n";
would confirm that they are not the same. And if we do
$ref1->[0] = 'a';
$ref2->[0] = 'b';
then $a[0] would equal a and not b.
You can use
perl -e 'my @a=(1); my $ra=\@a; my $rca=[@a]; $ra->[0]=2; print @a, @{$ra}, @{$rca};'
221
to see that your assumption that [@existingarray] creates a reference to a copy of @existingarray is correct (and that myArray* isn't Perl).
WRT amon's revising my perl -e "..." (fails under bash) to perl -e '...' (fails under cmd.exe): Use the quotes that work for your shell.
The square brackets make a reference to a new array with a copy of what's in @existingarray at the time of the assignment.
