php - Call to undefined method Database::prepare() oop pdo -

i have constructor in users class:

            public function __construct($pdo)             {                 $this->pdo = $pdo;             } 

and that's how run it:

index.php:

include("config.php"); $users = new users($pdo); 

but don't want way, wanted have separated class database connection

created database.class.php

class database {     public function __construct()     {         try         {             $pdo = new pdo('mysql:host='.mysql_host.';dbname=driptone', mysql_user, mysql_password);             $pdo->setattribute(pdo::attr_errmode, pdo::errmode_exception);             echo 'connected';         }         catch(pdoexception $e)         {             echo $e->getmessage();         }     } } 

and used this:

$users = new users(new database()); 

i error:

connected fatal error: call undefined method database::prepare() in c:\xampp\htdocs\drip\class\users.class.php on line 75 

i tried static, same problem.

why happening? how can fix it? , secure injections/xss attacks?

            /**             * public method register             *             * registers user system, checking errors.             * if error found, throw new exception.             *             * @parm username username user posted.             * @parm password password user posted.             * @parm repassword validated password user posted.             * @parm email email user posted.             * @parm reemail validated email user posted.             * @parm day day user posted (for date of birth).             * @parm month month user posted (for date of birth).             * @parm year year user posted (for date of birth).             *             * @return return true means correct, register successfully.             **/              public function register($username, $password, $repassword, $email, $reemail, $day, $month, $year)             {                     global $pdo;                      // check if passwords matching.                     if ($password != $repassword)                     {                             throw new exception ("passwords not match.");                     }                     // check if emails matching.                     else if ($email != $reemail)                     {                             throw new exception ("emails not match.");                     }                      // main insert query                     $this->insert = $this->pdo->prepare                     ("                             insert users                             (user_name, user_password, user_email, user_birth)                             values                             (:username, :password, :email, :birth)                     ");                      //query check if username taken.                     $this->user = $this->pdo->prepare("select * users user_name = :name");                     $this->user->execute(array(":name" => $username));                      //query check if email taken.                     $this->email = $this->pdo->prepare("select * users user_email = :email");                     $this->email->execute(array(":email" => $email));                                            // checking if username taken using query.                     if ($this->user->rowcount())                     {                             throw new exception ("username in use");                     }                     // checking if email taken using query.                                      else if ($this->email->rowcount())                     {                             throw new exception ("email in use");                     }                     // checking if birth of date valid.                     else if ($day > 31 || $month > 12 || $year > date('y') || $year < 1925)                     {                             throw new exception ("invalid birth of date");                     }                     // checking if password more 5 characters long.                     else if (strlen($password) < 5)                     {                             throw new exception ("password short");                     }                     else                     {                             // fine, insert data.                              $this->insert->execute(array                             (                                     ":username" => $username,                                     ":password" => $password,                                     ":email" => $email,                                     ":birth" => $day.'/'.$month.'/'.$year                             ));                              //send verification                              $this->sendverification($username, $email);                             //finished processing, return true.                             return true;                     }             }