Re^2: -> Is Optional ?

Thanks for your sample code roboticus. I copied and ran it and discovered that an extra level of dereferencing is required. This was a good exercise in reference accessing. Below is your code with the modifications for the extra level of dereferencing. (Note: I commented out the line labeled "Wrong" so it would compile and run) Thanks again!

my @a = [ 1, 4, 9, 16];  # squares
my @b = [ 1, 8, 27, 64]; # cubes
my @c = [ \@a, \@b ];    # two arrays

my $d = \@a;
my $e = \@c;

# OK: @a is an array
print "Sample1: ", $a[0]->[0], "\n";

# Wrong: "Sample1: ", $d is a reference, not an array!
#print "Sample2: ", $d[0], "\n";

# OK: Both of these are fine, though
print "Sample3: ", $d->[0]->[0], "\n";
print "Sample4: ", $$d[0]->[0],  "\n";

# with multiple subscripts:
print "Sample5: ", $e->[0]->[0]->[0]->[0], "\n";
print "Sample6: ", $e->[0][0][0][0],       "\n";  # same as above, sin
+ce -> is optional between subscripts
print "Sample7: ", $$e[0][0][0][0],        "\n";  # also same as above
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Re^3: -> Is Optional ?
by Athanasius (Archbishop) on Dec 29, 2012 at 16:34 UTC

The line

my @a = [ 1, 4, 9, 16 ];  # squares
[download]

creates an anonymous array with 4 elements, and assigns a reference to this anonymous array — i.e., a single, scalar value — to be the first (and only) element of the named array @a.

I suspect that parentheses were intended rather than square brackets:

my @a = ( 1, 4,  9, 16 );  # squares
my @b = ( 1, 8, 27, 64 );  # cubes
my @c = ( \@a, \@b );      # two arrays
[download]

and then the rest of the original code behaves as intended.

Hope that helps,

Athanasius <°(((>< contra mundum Iustus alius egestas vitae, eros Piratica,

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