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Re^2: -> Is Optional ?

by roho (Canon)
on Dec 29, 2012 at 16:15 UTC ( #1010823=note: print w/replies, xml ) Need Help??

in reply to Re: -> Is Optional ?
in thread -> 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

"Its not how hard you work, its how much you get done."

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Re^3: -> Is Optional ?
by Athanasius (Chancellor) on Dec 29, 2012 at 16:34 UTC

    The line

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

    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

    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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