From php5 and later versions, classes can use magic methods. PHP stipulates that methods starting with two underscores (__) are reserved as magic methods, so it is recommended that function names do not start with __ unless it is to overload existing magic methods.
The existing magic methods in PHP include __construct, __destruct, __call, __get, __set, __isset, __unset, __sleep, __wakeup, __toString, __set_state and __clone.
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__isset() - When using the isset() method on a class attribute or a non-class attribute, if there is no or non-public attribute, the __isset() method will be automatically executed.
__unset() -When using the unset() method on a class attribute or a non-class attribute, if there is no or non-public attribute, the __unset() method will be automatically executed
<?php /** * 针对类中的魔术方法 __isset() 和 __unset() 的例子 */ class Example { public $public; protected $protected; private $private; public function __construct(){ $this->public = 'pub'; $this->protected = 'pro'; $this->private = 'pri'; } public function __isset($var){ echo '这里通过__isset()方法查看属性名为 '.$var."\n"; } public function __unset($var){ echo '这里通过__unset()方法要销毁属性名为 '.$var."\n"; } } $exa = new Example; echo '<pre class="brush:php;toolbar:false">'; var_dump(isset($exa->public)); echo "\n"; var_dump(isset($exa->protected)); echo "\n"; var_dump(isset($exa->private)); echo "\n"; var_dump(isset($exa->noVar)); echo "\n"; echo '<hr>'; unset($exa->public); var_dump($exa); echo "\n"; unset($exa->protected); echo "\n"; unset($exa->private); echo "\n"; unset($exa->noVar); echo "\n";
The result is as follows:
bool(<span>true</span><span>) 这里通过__isset()方法查看属性名为 protected bool(</span><span>false</span><span>) 这里通过__isset()方法查看属性名为 private bool(</span><span>false</span><span>) 这里通过__isset()方法查看属性名为 noVar bool(</span><span>false</span><span>) ------------------------------------------------------------------------------ </span><span>object</span>(Example)#<span>1</span> (<span>2</span><span>) { [</span><span>"</span><span>protected:protected"]=></span> <span>string</span>(<span>3</span>) <span>"</span><span>pro"</span> [<span>"</span><span>private:private"]=></span> <span>string</span>(<span>3</span>) <span>"</span><span>pri"</span> <span>} 这里通过__unset()方法要销毁属性名为 protected 这里通过__unset()方法要销毁属性名为 private 这里通过__unset()方法要销毁属性名为 noVar</span>
The above introduces the PHP magic methods: __isset and __unset, including the content of PHP magic methods. I hope it will be helpful to friends who are interested in PHP tutorials.

PHP is used to build dynamic websites, and its core functions include: 1. Generate dynamic content and generate web pages in real time by connecting with the database; 2. Process user interaction and form submissions, verify inputs and respond to operations; 3. Manage sessions and user authentication to provide a personalized experience; 4. Optimize performance and follow best practices to improve website efficiency and security.

PHP uses MySQLi and PDO extensions to interact in database operations and server-side logic processing, and processes server-side logic through functions such as session management. 1) Use MySQLi or PDO to connect to the database and execute SQL queries. 2) Handle HTTP requests and user status through session management and other functions. 3) Use transactions to ensure the atomicity of database operations. 4) Prevent SQL injection, use exception handling and closing connections for debugging. 5) Optimize performance through indexing and cache, write highly readable code and perform error handling.

Using preprocessing statements and PDO in PHP can effectively prevent SQL injection attacks. 1) Use PDO to connect to the database and set the error mode. 2) Create preprocessing statements through the prepare method and pass data using placeholders and execute methods. 3) Process query results and ensure the security and performance of the code.

PHP and Python have their own advantages and disadvantages, and the choice depends on project needs and personal preferences. 1.PHP is suitable for rapid development and maintenance of large-scale web applications. 2. Python dominates the field of data science and machine learning.

PHP is widely used in e-commerce, content management systems and API development. 1) E-commerce: used for shopping cart function and payment processing. 2) Content management system: used for dynamic content generation and user management. 3) API development: used for RESTful API development and API security. Through performance optimization and best practices, the efficiency and maintainability of PHP applications are improved.

PHP makes it easy to create interactive web content. 1) Dynamically generate content by embedding HTML and display it in real time based on user input or database data. 2) Process form submission and generate dynamic output to ensure that htmlspecialchars is used to prevent XSS. 3) Use MySQL to create a user registration system, and use password_hash and preprocessing statements to enhance security. Mastering these techniques will improve the efficiency of web development.

PHP and Python each have their own advantages, and choose according to project requirements. 1.PHP is suitable for web development, especially for rapid development and maintenance of websites. 2. Python is suitable for data science, machine learning and artificial intelligence, with concise syntax and suitable for beginners.

PHP is still dynamic and still occupies an important position in the field of modern programming. 1) PHP's simplicity and powerful community support make it widely used in web development; 2) Its flexibility and stability make it outstanding in handling web forms, database operations and file processing; 3) PHP is constantly evolving and optimizing, suitable for beginners and experienced developers.


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