$ perl -E'%h=(a=>1,b=>1,c=>1); while (my ($k) = each(%h)) { say $k; }'
c
a
b

$ perl -E'%h=(a=>1,b=>1,c=>1); while (my ($k) = each(%h)) { say $k; delete $h{d}; }'
c
a
b

##</code><code>##

$ perl -E'my @a = (4,5); say 0+@a; delete $a[10]; say 0+@a;'
2
2

##</code><code>##

$ perl -E'my %h; delete $h{x}; say "ok";'
ok

##</code><code>##

$ perl -E'my %h = (x=>1); delete $h{x}; delete $h{x}; say "ok";'
ok