In php how do I call function from another class inside a different class?

Question

how do I call function from another class inside a different class?

Here's my current code:

    <?php

    class database
    {
        private $host = "localhost";
        private $user = "root";
        private $password = "";
        private $db = "9dot";

        //connect to database
        public function connect()
        {
            $connect =  mysql_connect($this->host,$this->user,$this->password);
            $database = mysql_select_db($this->db,$connect);

        }



        //Get exam headers
        public function GetExam()
        {
            $this->connect();
            $select = "SELECT e.ExamHeaderID, CONCAT(e.Firstname,' ',e.Lastname) AS Fullname e.Age, e.Position, e.Date FROM examheader e";
            $result = mysql_query($select);
            $table = "";
            $table .= "<th>ExamID</th>";
            $table .= "<th>Name</th>";
            $table .= "<th>Age</th>";
            $table .= "<th>Position</th>";
            $table .= "<th>Date</th>";

            $exam_id = "";
            $fullname = "";
            $age = "";
            $position = "";
            $date = "";
            while($row = mysql_fetch_array($select))
            {
                $exam_id = mysql_real_escape_string($row['ExamHeaderID']);
                $fullname = mysql_real_escape_string($row['Fullname']);
                $age = mysql_real_escape_string($row['Age']);
                $position = mysql_real_escape_string($row['Position']);
                $date = mysql_real_escape_string($row['Date']);
            }

        }

        public function GetExamDetails($ExamID)
        {
            $this->connect();
            //$select = "SELECT ed.ExamDetailsID, ed.";
        }


        //Save Exam header
        public function SaveExam($firstname,$lastname, $age, $position)
        {
            $this->connect();
            $date = date("m/d/Y");
            mysql_real_escape_string($firstname);
            mysql_real_escape_string($lastname);
            mysql_real_escape_string($age);
            mysql_real_escape_string($position);
            $insert = "INSERT INTO examheader (Firstname,Lastname, Age, Position, Date) VALUES ('$firstname','$lastname','$age','$position')";
            $result = mysql_query($insert);
            $exam_id = mysql_insert_id();
            //return exam id for insertion of exam details
            return $exam_id;

        }

        public function SaveExamAnswer()
        {


        }



    }

?>





<?php

include 'database.php';
$database = new $database();

class department
{
    $database->//property or function
}



?>

How do I call functions from database class

Answer 1

You can declare the instance of database in the department class like below :

class department
{
    public function __construct() 
    {
        $database = new database();
        $database->someFunction();
    }
}

If you don't wanna have it directly in your department class, you can declare it using the global system, assuming that the file needed is included, like below :

include 'database.php'

$database = new database();

class department
{
    public function __construct() 
    {
        global $database;
        $database->someFunction();
    }
}

See PHP: Variable scope