PHP's serialize() serialization function_PHP tutorial

The explanation of serialize() and unserialize() in the PHP manual is:

serialize — Generates a storable representation of a value, generates a storable representation of a value.

unserialize — Creates a PHP value from a stored representation, creates a PHP value from a stored representation.

serialize() returns a string, which contains a byte stream representing value and can be stored anywhere. This facilitates storing or passing PHP values ​​without losing their type and structure.

To convert a serialized string back into a PHP value, use unserialize() . serialize() can handle any type except resource. You can even serialize() arrays that contain references to themselves. References in the array/object you are serializing() will also be stored.

When serializing an object, PHP will attempt to call the object's member function __sleep() before the sequence action. This allows any cleanup operations to be done before the object is serialized. Similarly, when an object is restored using unserialize(), the __wakeup() member function will be called.

Let’s try how to use this function:

<?php
//声明一个类
class dog {
    var $name;
    var $age;
    var $owner;
    function dog($in_name="unnamed", $in_age="0", $in_owner="unknown") {
        $this->name = $in_name;
        $this->age = $in_age;
        $this->owner = $in_owner;
    }
    function getage() {
        return ($this->age * 365);
    }
    
    function getowner() {
        return ($this->owner);
    }
    
    function getname() {
        return ($this->name);
    }
}
//实例化这个类
$ourfirstdog = new dog("Rover",12,"Lisa and Graham");
//用serialize函数将这个实例转化为一个序列化的字符串
$dogdisc = serialize($ourfirstdog);
print $dogdisc; //$ourfirstdog 已经序列化为字符串 O:3:"dog":3:{s:4:"name";s:5:"Rover";s:3:"age";i:12;s:5:"owner";s:15:"Lisa and Graham";}
print '<br />';
/* 
-----------------------------------------------------------------------------------------
    在这里你可以将字符串 $dogdisc 存储到任何地方如 session,cookie,数据库,php文件 
-----------------------------------------------------------------------------------------
*/
//我们在此注销这个类
unset($ourfirstdog);
/*    还原操作   */
/* 
-----------------------------------------------------------------------------------------
    在这里将字符串 $dogdisc 从你存储的地方读出来如 session,cookie,数据库,php文件 
-----------------------------------------------------------------------------------------
*/
//我们在这里用 unserialize() 还原已经序列化的对象
$pet = unserialize($dogdisc); //此时的 $pet 已经是前面的 $ourfirstdog 对象了
//获得年龄和名字属性
$old = $pet->getage();
$name = $pet->getname();
//这个类此时无需实例化可以继续使用,而且属性和值都是保持在序列化之前的状态
print "Our first dog is called $name and is $old days old<br />";
print '<br />';
?>

An official program example:

<?php 
// $session_data 是包含了当前用户 session 信息的多维数组。 
// 我们使用 serialize() 在请求结束之前将其存储到数据库中。 
$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 )) { 
     /* 出错 */ 
     } 
} 
?>

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