use strict;
use Data::Dumper;

my %h = (
            'John'         => 'P9111',
            'Bob'          => 4711,
            'xavier'       => '20040610',
            'alice'        => '20040610',
        );

my %sk = map ({$_, ($_ =~ m/^[a-z]/) ? 0 : 1} (keys %h));
print Dumper %sk;

my @xk = (sort {$sk{$a} <=> $sk{$b} || $a cmp $b} keys %sk);

print Dumper @xk;

___OUTPUT___
$VAR1 = 'Bob';
$VAR2 = 1;
$VAR3 = 'alice';
$VAR4 = 0;
$VAR5 = 'John';
$VAR6 = 1;
$VAR7 = 'xavier';
$VAR8 = 0;


$VAR1 = 'alice';
$VAR2 = 'xavier';
$VAR3 = 'Bob';
$VAR4 = 'John';