note 114999 added to function.mt-rand

I was seeing how much unique and random 5-digits number I can use/generate in one-second's interval of time. (I had another logic for myself to make my number unique based on the date/time stamp value as well). I found that the mt_rand() numbers are not quite unique. The repetitions will often occur a lot of times even in the first 50 random numbers generated in a loop. <?php header('Content-Type: text/plain'); $errors = array(); $uniques = array(); for($i = 0; $i < 500; ++$i) { $random_code = mt_rand(10000, 99999); if(!in_array($random_code, $uniques)) { $uniques[] = $random_code; } else { $errors[] = $random_code; } } /** * If you get any data in this array, it is not exactly unique * Run this script for few times and you may see some repeats */ print_r($errors); ?> ---- Server IP: 72.52.91.14 Probable Submitter: 92.97.207.228 ---- Manual Page -- http://php.net/manual/en/function.mt-rand.php Edit -- https://master.php.net/note/edit/114999 Del: integrated -- https://master.php.net/note/delete/114999/integrated Del: useless -- https://master.php.net/note/delete/114999/useless Del: bad code -- https://master.php.net/note/delete/114999/bad+code Del: spam -- https://master.php.net/note/delete/114999/spam Del: non-english -- https://master.php.net/note/delete/114999/non-english Del: in docs -- https://master.php.net/note/delete/114999/in+docs Del: other reasons-- https://master.php.net/note/delete/114999 Reject -- https://master.php.net/note/reject/114999 Search -- https://master.php.net/manage/user-notes.php