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list/array context mystery

by cajun2019 (Initiate)
on Apr 24, 2001 at 03:29 UTC ( #74912=perlquestion: print w/replies, xml ) Need Help??

cajun2019 has asked for the wisdom of the Perl Monks concerning the following question:

Apparently (undef)[0] is being interpreted as a null list. In the context of the other statements, why is that? Thanks...
%tmp= (nothing => undef, one => 1); # $tmp{nothing} is undef %tmp= (nothing => (0, undef)[0], one => 1); # $tmp{nothing} == 0 %tmp= (nothing => [undef, 0]->[0], one => 1); # $tmp{nothing} is undef %tmp= (nothing => scalar ((0, undef)[1]), one => 1); # $tmp{nothing} is undef %tmp= (nothing => (undef), one => 1); # $tmp{nothing} is undef %tmp= (nothing => (undef)[0], one => 1); # $tmp{nothing} eq 'one'*** Why not undef? %tmp= (nothing => (undef, 0)[0], one => 1); # $tmp{nothing} eq 'one'*** Why not undef? 1;

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Re: list/array context mystery
by clintp (Curate) on Apr 24, 2001 at 04:19 UTC
    For what it's worth, under 5.6 the last two examples do result in undef.

    Under 5.00503 (the only older version I had laying around) it produces "one". You might want to wander through the changelogs for 5.6 and see what might have fixed this if you're really curious.

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