Algorithms

creating unique ids (strings)

Type:	code fragment
Added by:	charles_killian
Entered:	04/10/2000
Last modified:	01/12/2000
Rating:	(4 votes)
Views:	9111

Below are two functions I use to create unique ids: The first uses unique_id() and md5(). (I think I copied it from the manual). The second is useful if you want to restrict the unique id to a specific length and character set ( I think I copied it from Core PHP).

<?php
function get_md5_unique_id(){

                             mt_srand ((double) microtime() * 1000000);

                             return $unique_id = md5(uniqid(mt_rand(),1));

                            }// end get_md5_unique_id

                            
 function get_unique_id($length=32, $pool=""){

                             // set pool of possible char

                             if($pool == ""){

                              $pool = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";

                              $pool .= "abcdefghijklmnopqrstuvwxyz";

                              $pool .= "0123456789";

                             }// end if

                             mt_srand ((double) microtime() * 1000000);

                             $unique_id = "";

                             for ($index = 0; $index < $length; $index++) {

                              $unique_id .= substr($pool, (mt_rand()%(strlen($pool))), 1);

                             }// end for

                             return($unique_id);

                            }// end get_unique_id

                            
 ?>

Usage Example

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