PHP Manual: serialize

Description

string serialize ( mixed value )

serialize() returns a string containing a byte-stream representation of value that can be stored anywhere.

This is useful for storing or passing PHP values around without losing their type and structure.

To make the serialized string into a PHP value again, use unserialize(). serialize() handles all types, except the resource-type. You can even serialize() arrays that contain references to itself. Circular references inside the array/object you are serialize()ing will also be stored. Any other reference will be lost.

When serializing objects, PHP will attempt to call the member function __sleep() prior to serialization. This is to allow the object to do any last minute clean-up, etc. prior to being serialized. Likewise, when the object is restored using unserialize() the __wakeup() member function is called.

Note: This didn't work correctly until 4.0.7.

Note: In PHP 3, object properties will be serialized, but methods are lost. That limitation was removed in PHP 4 as both properties and methods are now restored. Please see the Serializing Objects section of Classes and Objects for more information.
It is not possible to serialize PHP built-in objects.

Example 1. serialize() example

<?php
// $session_data contains a multi-dimensional array with session
// information for the current user.  We use serialize() to store
// it in a database at the end of the request.

$conn = odbc_connect("webdb", "php", "chicken");
$stmt = odbc_prepare($conn,
      "UPDATE sessions SET data = ? WHERE id = ?");
$sqldata = array (serialize($session_data), $PHP_AUTH_USER);
if (!odbc_execute($stmt, &$sqldata)) {
    $stmt = odbc_prepare($conn,
     "INSERT INTO sessions (id, data) VALUES(?, ?)");
    if (!odbc_execute($stmt, &$sqldata)) {
        /* Something went wrong.. */
    }
}
?>