在php中，如何从不同类中的另一个类调用函数？

如何从不同类中的另一个类调用函数

以下是我当前的代码：

    <?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
}



?>

尝试类似的方法（粗略示例）：


您可以扩展它们

class department extends database {
    function test() {
        $this->getdbfunction();
    }
}

或者你把它们交给构造器：

class department {
    private $db;

    public function __construct(Database db) {
        $this->db = $db
    }
}

$department = new department($database);

创建“database”类型的对象，然后使用以下方法调用该方法：

$database = new database();
$connection = $database->connect();

您可以定义一个属性，该属性是第一个类的实例，然后在第二个类示例中将方法应用于已定义的属性：

class A {
function a () {
}
...
}

class B {
$attClassA;
function __construct(A objA) {
$this->attClassA = objA;
}
// you can use the attClassA in any class you want and then apply the chosen method
...
}

您可以在department类中声明数据库实例，如下所示：

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

include 'database.php'

$database = new database();

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

如果您不想直接在department类中使用它，您可以使用
全局
系统声明它，假设包含所需的文件，如下所示：

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

include 'database.php'

$database = new database();

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

请参见您可以这样做：

如果不想手动包含PHP文件，请使用spl\u autoload\u register（）函数
否则，您需要包含PHP文件，该文件包含要从中导入方法的类

file-A.php-包含类A的php文件

<?php

class A{

   function DoSquare($x){
      return $x*$x;
    }

}

?>




file-B.php-包含类B的php文件

假设您使用的是spl_autoload_register（）：



如果手动包含PHP文件：

<?php

require("file-A.php");

class B{
   
   private $ObjectA = NULL;

   public function __construct(){
        $this->ObjectA = new A();
    }

   public function PrintSquare($x){
       echo $this->ObjectA->DoSquare($x);      
   }

}
?>


不要鼓励人们使用
global
！我不鼓励他使用它，我只是告诉他，这也是他想做什么的另一种方式，即使这不是最正确的方式。在大多数人看来，依赖注入方法是首选方法；）当您查看性能时，您应该查看并使用设计模式，因此这个示例非常简单。