$ perl -wle 'my $a=[2,3,4]; delete($a->[1]); print scalar @$a'
3
$ perl -wle 'my $a=[2,3,4]; delete($a->[1]); print scalar @$a'
3
$ perl -wle 'my $a=[2,3,4]; delete($a->[2]); print scalar @$a'
2