I have a very small image viewer script which has a database full of id numbers from 1 - infinity. I delete a few of them from the database and my script knows how to ++ or -- to the next eligible entry in case there's a gap in ids.

I wrote the code quite a few years ago and now I'm thinking there's GOT to be a better way to do this. Here's a sample of my script finding the next available image 

  # determine next eligible image
  my $next_cnt = 0;
  while ($lowest)
  {  
     $next_cnt++;
     if (exists $upload{$next_cnt})
     { 
        last;
     }

  } 
  $next_cnt = $next_cnt + 2; # jump one ahead

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I want to know if there's a way to determine what index a certain number is, inside my hash. Now I know indexes are used with arrays, but is there a similar way to do this in hashes if the keys are numbers?

Ie: 

1,2,3,5,9,10

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We are on image 5 and want to find out what the previous and next number in sequence would be.. 
my $prev = $db{$picid}..

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There just has to be a way to automatically determine, in a sorted hash, what the previous and next items would be. Right?

In reply to how to check which index $x is in an hash by Anonymous Monk

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