PHP : Constructor And Destructor

 Constructor And Destructor

PHP : Constructor And Destructor :

Php constructors(version 4) :

1.      A constructor is a function .

2.      Name of the constructor function is same as that of class name.

3.      A constructor function will gets automatically called when an object of a class is created.

4.      A constructor is used to initialize the member datas of an object.

Php Constructor(version 5) :

1.      In php5 a constructor is defined by implementing  _constructor() method, when an object is created , php5 searches for __construct() first. If __construct is not defined them it searches for a method with a name same that of the class.

Php5 destructor :

A destructor is a special function of a class that is automatically executed whenever an object of a class is destroyed.

 An object of a class is destroyed when :

1.      The program execution is over.

2.      It goes out of scope.

3.      You specifically set it to null.

4.      You unset it.

A php5 destructor is defined by implementing the __destruct() method.

<?php

class constrdestr

{

    private $empno,$ename,$sal;

    //php4 constructor

    function constrdestr($a=0,$b="na" ,$c=0)

    {

        echo "******<br>";

        $this->empno=$a;

        $this->ename=$b;

        $this->sal=$c;

       

    }

    //php5 constructor

    function __construct($a=0,$b="na" ,$c=0)

    {

        echo "??????<br>";

        $this->empno=$a;

        $this->ename=$b;

        $this->sal=$c;

       

    }

    //php5 destructor

    function __destruct() {

        echo "inside destructor<br>";

    }

    function getData()

    {

        echo $this->empno."--".$this->ename."--".$this->sal."<br>";

    }

}

?>

<?php

echo "<h1>";

$emp1 =new constrdestr();

$emp2 =new constrdestr(101,"penna");

$emp3 = new constrdestr(102,"lpo",123.45);

$emp1->getData();

$emp2->getData();

$emp3->getData();

unset($emp1);

$emp2 =11;

$emp3=NULL;

echo "application completed!!!";

?>

OutPut:

??????

??????

??????

0--na--0

101--penna--0

102--lpo--123.45

inside destructor

inside destructor

inside destructor

application completed!!!