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I did an online Perl exam today and it made we wonder: Is the answer to this question really deterministic?
# Enter the output of the following: use strict; use warnings; my %hash = ("Zero","0","One","1","Two","2"); my @array = keys %hash; print "$array[0]\n"; __END__
keys says:
The keys are returned in an apparently random order. The actual random order is subject to change in future versions of perl, but it is guaranteed to be the same order as either the "values" or "each" function produces (given that the hash has not been modified). Since Perl 5.8.1 the ordering is different even between different runs of Perl for security reasons (see "Algorithmic Complexity Attacks" in perlsec).
Nevertheless, I'm not able to see the that the keys are returned in random order. What am I missing?
$ cat foo.t use strict; use warnings; use Test::More; plan tests => 10_000; sub get { my %hash = ("Zero","0","One","1","Two","2"); my @array = keys %hash; return $array[0]; } for (1 .. 10_000) { ok(get() eq 'Zero', q{Expect Zero}); } __END__ $ /usr/bin/prove foo.t foo....ok All tests successful. Files=1, Tests=10000, 5 wallclock secs ( 2.18 cusr + 0.06 csys = 2. +24 CPU)
For the record:
This is perl, v5.8.5 built for i386-linux-thread-multi
No matter how great and destructive your problems may seem now, remember, you've probably only seen the tip of them. [1]

In reply to Deterministic or keys in random order by andreas1234567

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