Detailed introduction to PHP's curl function (summary)

This article brings you a detailed introduction (summary) about PHP's curl function. It has certain reference value. Friends in need can refer to it. I hope it will be helpful to you.

To use cURL to send url requests, the specific steps are roughly divided into the following Four steps:

1.Initialization
2.Set request options
3 .Execute a cURL session and get related replies
4. Release the cURL handle and close a cURL session

curl basic example:

<?php
// 创建一个新cURL资源
$ch = curl_init();

// 设置URL和相应的选项
curl_setopt($ch, CURLOPT_URL, "http://www.example.com/");
curl_setopt($ch, CURLOPT_HEADER, false);

// 抓取URL并把它传递给浏览器
curl_exec($ch);

//关闭cURL资源，并且释放系统资源
curl_close($ch);
?>

Recommended related practical tutorials: 《PHP uses CURL to capture pages》, can be operated online!

##curl function summary:

• curl_close — Close a cURL session

• curl_copy_handle — Copy a cURL handle and all its options

• curl_errno — Return to last Error number

• curl_error — Returns a string that protects the most recent error in the current session.

• curl_escape — URL-encodes the given characters String

• curl_exec — Execute a cURL session

• curl_file_create — Create a CURLFile object

• curl_getinfo — Obtain information about a cURL connection resource handle

• curl_init — Initialize a cURL session

• curl_multi_add_handle — Add a separate cURL session to a curl batch session curl handle

• curl_multi_close — Close a group of cURL handles

• curl_multi_exec — Run a sub-connection of the current cURL handle

• curl_multi_getcontent — If CURLOPT_RETURNTRANSFER is set, return the text stream of the obtained output

• curl_multi_info_read — Get the relevant transport information of the currently parsed cURL

• curl_multi_init — Returns a new cURL batch handle

• curl_multi_remove_handle — Removes a handle resource in the curl batch handle resource

• curl_multi_select — Wait for active connections in all cURL batches

• curl_multi_setopt — Set an option for cURL parallel processing

• curl_multi_strerror — Return string describing error code

• curl_pause — Pause and unpause a connection

• curl_reset — Resets all options for a libcurl session handle

• curl_setopt_array — Set options for a cURL transfer session in batches

• curl_setopt — Set a cURL transfer option

• curl_share_close — Close a cURL share handle

• curl_share_init — Initialize a cURL share handle

##curl_share_setopt — Set an option for a cURL share handle.
curl_strerror — Return string describing the given error code
curl_unescape — Decode the given URL encoded string
curl_version — Get cURL version information

CURLOPT_INFILESIZE: When you upload a file to the remote site, this option tells PHP the size of the file you uploaded.
CURLOPT_VERBOSE: If you want CURL to report every unexpected event, set this option to a non-zero value.
CURLOPT_HEADER: If you want to include a header in the output, set this option to a non-zero value.
CURLOPT_NOPROGRESS: If you do not want PHP to display a progress bar for CURL transfers, set this option to a non-zero value.

PHP automatically sets this option to a non-zero value, you should change this option only for debugging purposes.

CURLOPT_NOBODY: If you do not want to include the body part in the output, set this option to a non-zero value.
CURLOPT_FAILONERROR: If you want PHP not to display when an error occurs (HTTP code return greater than or equal to 300), set this option to a non-zero value. The default behavior is to return a normal page and ignore the code.
CURLOPT_UPLOAD: If you want PHP to prepare for uploading, set this option to a non-zero value.
CURLOPT_POST: If you want PHP to do a regular HTTP POST, set this option to a non-zero value. This POST is of the ordinary application/x-www-from-urlencoded type, mostly used by HTML forms.
CURLOPT_FTPLISTONLY: Set this option to a non-zero value and PHP will list the directory names for FTP.
CURLOPT_FTPAPPEND: Set this option to a non-zero value and PHP will apply the remote file instead of overwriting it.

• CURLOPT_NETRC: Set this option to a non-zero value and PHP will look in your ~./netrc file for the username and password of the remote site you want to connect to.

• CURLOPT_FOLLOWLOCATION: Set this option to a non-zero header (like 'Location: ') and the server will send it as part of the HTTP header (note that this is recursive, PHP A header of the form 'Location: ' will be sent).

• CURLOPT_PUT: Set this option to a non-zero value to upload a file using HTTP. To upload this file you must set the CURLOPT_INFILE and CURLOPT_INFILESIZE options.

• CURLOPT_MUTE: Set this option to a non-zero value and PHP will be completely silent for the CURL function.

• CURLOPT_TIMEOUT: Set a long integer as the maximum number of seconds.

• CURLOPT_LOW_SPEED_LIMIT: Set a long integer to control how many bytes are transmitted.

• CURLOPT_LOW_SPEED_TIME: Set a long integer to control how many seconds to transmit the number of bytes specified by CURLOPT_LOW_SPEED_LIMIT.

• CURLOPT_RESUME_FROM: Pass a long parameter containing the byte offset address, (the start form you want to transfer to).

• CURLOPT_SSLVERSION: Pass a long parameter containing the SSL version. By default PHP will do its own hard work, in more security you have to set it manually.

• CURLOPT_TIMECONDITION: Pass a long parameter to specify how to handle the CURLOPT_TIMEVALUE parameter. You can set this parameter to TIMECOND_IFMODSINCE or TIMECOND_ISUNMODSINCE. This is only for HTTP.

• CURLOPT_TIMEVALUE: Pass a number of seconds from 1970-1-1 to now. This time will be used as the specified value by the CURLOPT_TIMEVALUE option, or by the default TIMECOND_IFMODSINCE.

The values ​​of the following options will be treated as strings:

• CURLOPT_URL: This is the value you want to retrieve using PHP URL address. You can also set this option during initialization with the curl_init() function.

• CURLOPT_USERPWD: Pass a string in the form of [username]:[password] and use PHP to connect.

• CURLOPT_PROXYUSERPWD: Pass a string in the format [username]:[password] to connect to the HTTP proxy.

• CURLOPT_RANGE: Pass a range you want to specify. It should be in 'X-Y' format, with X or Y being excluded. HTTP transfers also support several intervals, separated by commas (X-Y,N-M).

• CURLOPT_POSTFIELDS: Pass a string containing all the data as an HTTP "POST" operation.

• CURLOPT_REFERER: A string containing a 'referer' header in the HTTP request.

• CURLOPT_USERAGENT: A string containing a 'user-agent' header in the HTTP request.

• CURLOPT_FTPPORT: Pass an IP address containing the IP address used by the ftp ‘POST’ command. This POST command tells the remote server to connect to the IP address we specified. This string can be an IP address, a host name, a network interface name (under UNIX), or '-' (use the system default IP address).

• CURLOPT_COOKIE: Pass a header connection containing an HTTP cookie.

• CURLOPT_SSLCERT: Pass a string containing the certificate in PEM format.

• CURLOPT_SSLCERTPASSWD: Pass a password containing the necessary password to use the CURLOPT_SSLCERT certificate.

• CURLOPT_COOKIEFILE: Pass a string containing the name of the file containing cookie data. This cookie file can be in Netscape format, or it can be a stack of HTTP-style headers stored in the file.

• CURLOPT_CUSTOMREQUEST: When making an HTTP request, pass a character to be used by GET or HEAD. This is useful for doing or another, more obscure, HTTP request.

Note: Do not do this before confirming that your server supports the command.

• The following options require a file description (obtained by using the fopen() function):

• CURLOPT_FILE: This The file will be the output file you sent. The default is STDOUT.

• CURLOPT_INFILE: This file is the input file you sent.

• CURLOPT_WRITEHEADER: This file contains the header part of your output.

• CURLOPT_STDERR: This file has errors written to it instead of stderr.

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