if(! function_exists ('get_rand_string') ) {

    function get_rand_string($len=6,$format='ALL') {

         switch($format) {

             case 'ALL':

                 $chars='ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-@#~'; break;

             case 'CHAR':

                 $chars='ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz-@#~'; break;

             case 'NUMBER':

                 $chars='0123456789'; break;

             default :

                 $chars='ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-@#~';

                 break;

         }

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

         $password="";

         while(strlen($password)<$len)

            $password.=substr($chars,(mt_rand()%strlen($chars)),1);

         return $password;

     }

}