What does the php curl request header field mean?

php The curl request header field is a PHP extension library that simulates the request and response data between the client and the server. It is mainly used for data interaction with various servers such as HTTP/HTTPS/FTP.

Operating system for this tutorial: Windows 10 system, PHP version 8.1, Dell G3 computer

1. Structure of HTTP request

Before learning the request header field, we need to first understand the basic structure of the HTTP request. An HTTP request consists of three parts: a request line, a request header field, and a request body. The request header field is an important part of the HTTP protocol and is used to describe information related to the HTTP request.

2. The use of curl function in PHP

PHP curl is a PHP extension library that simulates the request and response data between the client and the server. Its main application For data interaction with various servers such as HTTP/HTTPS/FTP. The calling format of the curl function is as follows:

$ch = curl_init(); // 初始化curl
curl_setopt($ch, CURLOPT_URL, $url); // 设置要请求的URL地址
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1); // 数据不直接输出
curl_setopt($ch, CURLOPT_HEADER, 0); // 不输出响应头部信息
curl_setopt($ch, CURLOPT_POST, 1); // 发送POST请求
curl_setopt($ch, CURLOPT_POSTFIELDS, $postdata); // POST数据
curl_setopt($ch, CURLOPT_HTTPHEADER, $headers); // 请求头域
$output = curl_exec($ch); // 发送请求并获得响应数据
curl_close($ch); // 关闭curl连接其中，curl_setopt()函数用于设置curl的各种参数选项。其中，CURLOPT_HTTPHEADER参数用于设置请求头域相关的信息。

3. The role of the request header field

Normally, the HTTP request header field includes the information that the client wants to send to the server. Various information, such as:

User-Agent: client device information, including operating system, browser version, etc.; Accept: client indicates the type of response data it can accept; Cookie: client saves cookie information.

In the curl function, you can set the request header field by setting the CURLOPT_HTTPHEADER parameter, for example:

$headers = array('User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:76.0) Gecko/20100101 Firefox/76.0',
                  'Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8',
                  'Cookie: PHPSESSID=abcdefg123456');
curl_setopt($ch, CURLOPT_HTTPHEADER, $headers); // 设置请求头域

In this way, when sending a request to the server, you can make a request with the HTTP header information you need. .

4. Summary

This article mainly introduces the meaning and function of the PHP curl request header field. As you can see, setting the request header field in PHP's curl function is very simple. Just call the curl_setopt() function and set the CURLOPT_HTTPHEADER parameter. I hope this article can provide a certain understanding and mastery of the PHP curl request header field and help developers better set HTTP request parameters and application development.

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