c:\@Work\Perl>perl -wMstrict -le
"use Data::Dumper;
  my %hash;
  my @data = ('0', 'zero', 'foo',1, 'bar',2, 'foo',3, 'baz',4);
  while (my $key = shift @data) {
      my $value = shift @data;
      push @{$hash{$key}}, $value;
  }
  print Dumper \%hash
"
$VAR1 = {};

##</code><code>##

c:\@Work\Perl>perl -wMstrict -le
"use Data::Dumper;
 ;;
 my @data = ('0', 'zero', 'foo',1, 'bar',2, 'foo',3, 'baz',4);
 ;;
 my %hash;
 while (@data) {
   my $k = shift @data;
   die qq{no value for key '$k'} unless @data;
   my $v = shift @data;
   push @{$hash{$k}}, $v;
   }
 print Dumper \%hash
"
$VAR1 = {
          'bar' => [
                     2
                   ],
          'baz' => [
                     4
                   ],
          '0' => [
                   'zero'
                 ],
          'foo' => [
                     1,
                     3
                   ]
        };