What are the built-in objects in php

php built-in objects are: 1. $_GET, obtain the parameters passed to the script through the HTTP GET method; 2. $_POST, obtain the parameters passed to the script through the HTTP POST method; 3. $_REQUEST, obtain the parameters passed to the script through the HTTP GET method; The parameters passed to the script by the GET and POST methods; 4. $_SESSION, stores and accesses session variables between different pages; 5. $_COOKIE, reads the cookies sent by the browser; 6. $_SERVER; 7. $_FILES, etc. wait.

The operating system of this tutorial: Windows10 system, PHP version 8.1.3, DELL G3 computer.

PHP is a widely used programming language that is widely used for web development. It provides many built-in objects to facilitate developers to perform various tasks, such as processing form data, accessing databases, and manipulating files.

1. $_GET: This is a built-in object used to obtain parameters passed to the script through the HTTP GET method. It is an associative array and the different parameters can be accessed by key name.

Example:

$id = $_GET['id']; // 获取名为“id”的参数值

2. $_POST: Similar to the $_GET object, $_POST is used to obtain the parameters passed to the script through the HTTP POST method. It is also an associative array, and different parameters can be accessed by key name.

Example:

$username = $_POST['username']; // 获取名为“username”的参数值

3. $_REQUEST: This built-in object can obtain parameters passed to the script through GET and POST methods at the same time. It is an associative array and the different parameters can be accessed by key name.

Example:

$name = $_REQUEST['name']; // 获取名为“name”的参数值

4. $_SESSION: This built-in object is used to store and access session variables between different pages. Session variables are accessible throughout the session and persist after the user closes the browser.

Example:

session_start(); // 启动会话
$_SESSION['username'] = 'John'; // 设置会话变量
$username = $_SESSION['username']; // 获取会话变量的值

5. $_COOKIE: This built-in object is used to read the Cookie sent by the browser. Cookies are small text files stored on your browser that are used to track and identify users.

Example:

$cookieValue = $_COOKIE['cookieName']; // 获取名为“cookieName”的Cookie的值

6. $_SERVER: This built-in object provides information about the server and execution environment of the current script. You can use this to get the script's file path, hostname, and other relevant information.

Example:

$filePath = $_SERVER['SCRIPT_FILENAME']; // 获取当前脚本文件的路径

7. $_FILES: This built-in object is used to handle files uploaded through the HTTP POST method. It provides some useful functions to obtain and process uploaded file information, such as file name, type, size, etc.

Example:

$fileName = $_FILES['file']['name']; // 获取上传文件的名称

In addition to some of the common built-in objects mentioned above, PHP also provides many other built-in objects, such as database-related objects (such as mysqli and PDO), date and time Related objects (such as DateTime) and image processing related objects (such as GD library and Imagick library), etc.

Built-in objects are one of the powerful features of PHP, allowing developers to easily handle and operate various tasks, improving development efficiency. Proficiency with these objects will help you better utilize PHP's capabilities.

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