A brief analysis of the usage of serialize and unserialize in php

PHP is a popular programming language commonly used for web development. Among them, serialize and unserialize are two very useful functions that can convert PHP objects into strings and deserialize them.

1. Usage of serialize

serialize is a PHP function used to convert PHP objects into strings that can be stored or transmitted. The basic syntax is as follows:

$serialized_string = serialize($object);

Among them, $object is the PHP object to be serialized, and $serialized_string is the string obtained after serializing the object.

For example, suppose we have a PHP object named $person whose properties include name, age, and gender:

$person = new stdClass;
$person->name = "Tom";
$person->age = 30;
$person->gender = "male";

We can use serialize to serialize it into a string:

$serialized_person = serialize($person);

You can use the echo statement to output $serialized_person to view the string obtained after serialization:

echo $serialized_person;

The output result is:

O:8:"stdClass":3:{s:4:"name";s:3:"Tom";s:3:"age";i:30;s:6:"gender";s:4:"male";}

You can see that the $person object was successfully converted for a long string. This string contains all the properties of the object, as well as the type and length of each property.

However, it should be noted that the serialized string cannot be directly used for display or storage, because it contains many special characters and is difficult to read and process.

2. Usage of unserialize

unserialize is the inverse function of serialize, used to convert serialized strings into PHP objects. The basic syntax is as follows:

$object = unserialize($serialized_string);

Among them, $serialized_string is the string to be deserialized, and $object is the PHP object obtained after deserialization.

For example, we can use the serialized string $serialized_person in the previous example and deserialize it into a new PHP object:

$unserialized_person = unserialize($serialized_person);

We can use the var_dump($unserialized_person) function Check whether the object obtained after deserialization is correct.

The output result is:

object(stdClass)#2 (3) {
  ["name"]=>
  string(3) "Tom"
  ["age"]=>
  int(30)
  ["gender"]=>
  string(4) "male"
}

You can see that the deserialization is successful and a new stdClass object $unserialized_person is obtained, whose attributes are exactly the same as $person.

3. Serializing arrays and objects

In the above example, we demonstrated how serialize and unserialize are used for stdClass objects. However, they can also handle other PHP arrays and objects.

For example, suppose we have an array containing multiple student information:

$students = array(
  array("name" => "Tom", "age" => 20, "gender" => "male"),
  array("name" => "Alice", "age" => 22, "gender" => "female"),
  array("name" => "Bob", "age" => 21, "gender" => "male"),
);

We can serialize $students into a string:

$serialized_students = serialize($students);

and pass the unserialize function It is deserialized into a new array:

$unserialized_students = unserialize($serialized_students);

You can also use the var_dump($unserialized_students) function to check whether the array obtained after deserialization is consistent.

4. Things to note when serializing

When using serialize and unserialize, you need to pay attention to the following points:

（ 1) Only objects with public properties can be serialized.

(2) The serialized string is related to the PHP version and operating system. Different versions of PHP may produce different serialization results.

(3) The serialization result contains all properties and methods of the object, so you need to pay attention to protecting private properties and methods.

5. Summary

serialize and unserialize are two very important functions in PHP, which can convert PHP objects into strings and deserialize them change. They can help us conveniently store and transmit data in web development. When using it, you need to pay attention to the properties and access rights of the object, as well as the serialization differences between different PHP versions.

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