Using __sleep()

Object serialization is another important aspect of OOP. PHP provides a serialize() function that allows us to serialize a value passed to it. The result is a string containing a byte-stream representation of any value that can be stored in PHP. Serializing the scalar data types and simple objects is pretty straightforward, as per the following example:

<?php

$age = 34;
$name = 'John';

$obj = new stdClass();
$obj->age = 34;
$obj->name = 'John';

var_dump(serialize($age));
var_dump(serialize($name));
var_dump(serialize($obj));

The resulting output is shown as follows:

string(5) "i:34;"
string(11) "s:4:"John";"
string(56) "O:8:"stdClass":2:{s:3:"age";i:34;s:4:"name";s:4:"John";}"

Even a simple custom class can be easily :

<?php

class User
{
  public $name = 'John';
  private $age = 34;
  protected $salary = 4200.00;
}

$user = new User();

var_dump(serialize($user));

The preceding code results in the following output:

string(81) "O:4:"User":3:{s:4:"name";s:4:"John"...