#!/usr/bin/perl -W
use strict;
use warnings;
use diagnostics;
use Fcntl qw(:DEFAULT :flock);
use Data::Dumper;
local $Data::Dumper::Sortkeys = \&dumper_sort;
sub dumper_sort {
    my ($hash) = @_;
    return [(sort {lc $a cmp lc $b} keys %$hash)];
}

my %test = (
    1 => 'foo',
    2 => 'bar',
    3 => 'foobar',
    4 => 'barfoo',
);
my $loesche = 2;
print Dumper (\%test);
if ($loesche == keys %test) {
    delete $test{$loesche};
}
else {
    for ($loesche + 1..keys %test) {
        $test{$_ - 1} = $test{$_};
        delete $test{$_};
    }
}
print Dumper (\%test);