my $current = 5;

my %hash = ( "1" => "one",
             "2" => "two",
             "3" => "three",
             "4" => "four",
             "5" => "five",
             "8" => "eight"
            );

while ($current)
{
   $current++;
   if (exists $hash{$current})
   { 
      print "next: $hash{$current}";
      last;
   }

}