ree:

Just a bit of clarification on RichardK's answer: Notice how it says 'between' subscripts. So after the first one, it's always optional. Before the first one, though, you need to tell perl that you're accessing a value through a reference, and there are two ways you can do so. Either add a '$' to the front, or use a '->' after the scalar:

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 $a[0];

# Wrong: $d is a reference, not an array!
print $d[0];

# OK: Both of these are fine, though
print $d->[0];
print $$d[0];

# with multiple subscripts:
print $e->[0]->[0];
print $e->[0][0];    # same as above, since -> is optional between sub
+scripts
print $$e[0][0];     # also same as above

[download]

You may find yourself preferring an extra '$' at the front (which is what I usually use) or using the '->' (which I use when I want to alert myself to the fact that I'm using a reference). You need to be comfortable with both, since you'll frequently encounter both notations.

Update: D'oh! I bungled my variable declarations, as caught by roho and explained by Athanasius. Corrected (converted square brackets to parenthesis in first three lines).

...roboticus

When your only tool is a hammer, all problems look like your thumb.

In reply to Re: -> Is Optional ? by roboticus
in thread -> Is Optional ? by vinoth.ree

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