Dear all,

I can't figure out how to optimally do the following in PHP: In a database, I have messages with a unique ID, like 19041985. Now, I want to refer to these messages in a short-url service but not using generated hashes but by simply 'calculate' the original ID.

In other words, for example: http://short.url/sYsn7 should let me calculate the message ID the visitor would like to request.

To make it more obvious, I wrote the following in PHP to generate these 'alphanumeric ID versions' and of course, the other way around will let me calculate the original message ID.

The question is: Is this the optimal way of doing this? I hardly think so, but can't think of anything else.

$alphanumString = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ-_'; for($i=0;$i < strlen($alphanumString);$i++) { $alphanumArray[$i] = substr($alphanumString,$i,1); }

$id = 19041985;

$out = ''; for($i=0;$i < strlen($id);$i++) {

if(isset($alphanumString["".substr($id,$i,2).""]) && strlen($alphanumString["".substr($id,$i,2).""]) > 0) { $out.=$alphanumString["".substr($id,$i,2).""]; } else { $out.=$alphanumString["".substr($id,$i,1).""]; $out.=$alphanumString["".substr($id,($i+1),1).""]; } $i++; }

print $out;