foreach questions

Hello; I have this section of code: @include('tmp_index.php'); foreach($index as $key -> $value)

          {
           if($input == $key)
             {
              $target_file = $value;
             }
          }

And I am getting this error: Fatal error: Cannot access empty property in <path>/confirmation.php on line 131 Several questions: How long can an index be in an associative array? (the indexes I use in this array are 32 character hashes) Can it start with a number (since a hash can start with a number) Can I use $index as an array name? (I do not remember off hand what the reserved key words are) I am not sure what the "empty property" is that it is referring to. Thank you in advance for info; Jeff K