Detailed explanation of using CURL in PHP

In PHP, CURL can be used to send HTTP requests and receive HTTP responses. The CURL library offers a set of functions that make it easy to use CURL in PHP.

Here are the basic steps for using CURL:

1. Initialize a cURL session

$ch = curl_init();

1. set a curl option

curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
// 设置请求头
curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
// 设置请求体
curl_setopt($ch, CURLOPT_POSTFIELDS, $data);

1. execute the cURL request

$response = curl_exec($ch);

1. Retrieve information regarding a cURL transfer.

$status_code = curl_getinfo($ch, CURLINFO_HTTP_CODE);
$header_size = curl_getinfo($ch, CURLINFO_HEADER_SIZE);
$headers = substr($response, 0, $header_size);
$body = substr($response, $header_size);

1. Close the curl session.

curl_close($ch);

The above steps can be adjusted and expanded according to actual needs, such as setting the timeout for requests, configuring proxies, handling redirects, and so on.

Here is a complete example demonstrating the process of sending a POST request and receiving a response using CURL.

$ch = curl_init();
$url = 'http://example.com/api';
$data = array('name' => 'John', 'age' => 30);
$headers = array('Content-Type: application/json');
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode($data));
$response = curl_exec($ch);
$status_code = curl_getinfo($ch, CURLINFO_HTTP_CODE);
curl_close($ch);

if ($status_code == 200) {
    // 处理响应
    echo $response;
} else {
    // 处理错误
    echo '请求失败：' . $status_code;
}

Please note that when using CURL to send a POST request, you need to convert the request body data to the corresponding format, such as converting it to JSON format as shown in the example above.

The above is the basic usage of CURL in PHP. CURL makes it easy to communicate with other servers, call APIs, and more.