HTTP protocol and status codes in PHP

PHP is a widely used server-side scripting language used to build web applications. In web applications, HTTP protocol and status codes are necessary basic knowledge, in this article we will explore the basic knowledge of HTTP protocol and status codes in PHP.

HTTP protocol is a protocol used to transmit hypertext and is widely used in Web development. Through the HTTP protocol, web browsers and web servers interact over the Internet. The web browser sends an HTTP request to the web server, and the web server receives the request and returns an HTTP response to the web browser. The HTTP protocol is a stateless protocol. It does not remember previous requests or responses, and each request and response is independent.

HTTP protocol is used in PHP by using the built-in HTTP function. The main HTTP functions are as follows:

1. file_get_contents: used to read content from a URL and return string type data.
2. get_headers: used to obtain the header information of an HTTP or HTTPS and return array type data.
3. stream_context_create: used to create a context for an HTTP request and return data of a resource type.
4. fopen: Used to open an HTTP or HTTPS URL and return resource type data.

Let’s take a look at the commonly used HTTP status codes in PHP. HTTP status codes are important signs of communication between web browsers and web servers. HTTP status codes represent what happened when the web server processed the request and the web server passed its response to the web browser. Common HTTP status codes include the following:

1. 200 OK: Indicates that the web server has successfully processed the request and returned the request result.
2. 301 Moved Permanently: Often used for website redirection, indicating that the requested resource has been permanently moved to a new address.
3. 302 Found: Often used for temporary redirection, indicating that the requested resource has been temporarily moved to a new address.
4. 404 Not Found: Indicates that the requested resource does not exist.
5. 500 Internal Server Error: Indicates that an error occurred when the web server processed the request.

In PHP, HTTP status codes can be sent through the header() function. For example, to send a 404 Not Found status code, you can use the following code:

header('HTTP/1.0 404 Not Found');

In this example, the header() function can Sets a text string in the HTTP response that specifies the HTTP status code that the web server should return.

Summary:

HTTP protocol and status code are inevitable basic knowledge in Web development. PHP uses the HTTP protocol by using the built-in HTTP function, and sends HTTP through the header() function. status code. Web developers need to carefully study and understand the HTTP protocol and status codes, which will help develop high-quality web applications.

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