CURLOPT_POST(3)

NAME
CURLOPT_POST - make an HTTP POST

SYNOPSIS
#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_POST, long post);

DESCRIPTION
A parameter set to 1 tells libcurl to do a regular HTTP post. This also makes libcurl use a "Content-Type: application/x-www-form-urlencoded" header. This is the most commonly used POST method.

Use one of CURLOPT_POSTFIELDS(3) or CURLOPT_COPYPOSTFIELDS(3) options to specify what data to post and CURLOPT_POSTFIELDSIZE(3) or CURLOPT_POSTFIELDSIZE_LARGE(3) to set the data size.

Optionally, you can provide data to POST using the CURLOPT_READFUNCTION(3) and CURLOPT_READDATA(3) options but then you must make sure to not set CURLOPT_POSTFIELDS(3) to anything but NULL. When providing data with a callback, you must transmit it using chunked transfer-encoding or you must set the size of the data with the CURLOPT_POSTFIELDSIZE(3) or CURLOPT_POSTFIELDSIZE_LARGE(3) options. To enable chunked encoding, pass in the appropriate Transfer-Encoding header, see the post-callback.c example.

You can override the default POST Content-Type: header by setting your own with CURLOPT_HTTPHEADER(3).

Using POST with HTTP 1.1 implies the use of a "Expect: 100-continue" header. You can disable this header with CURLOPT_HTTPHEADER(3) as usual.

If you use POST to an HTTP 1.1 server, you can send data without knowing the size before starting the POST if you use chunked encoding. You enable this by adding a header like "Transfer-Encoding: chunked" with CURLOPT_HTTPHEADER(3). With HTTP 1.0 or without chunked transfer, you must specify the size in the request. libcurl automatically uses chunked encoding for POSTs if the size is unknown.

When setting CURLOPT_POST(3) to 1, libcurl automatically sets CURLOPT_NOBODY(3) and CURLOPT_HTTPGET(3) to 0.

If you issue a POST request and then want to make a HEAD or GET using the same reused handle, you must explicitly set the new request type using CURLOPT_NOBODY(3) or CURLOPT_HTTPGET(3) or similar.

When setting CURLOPT_POST(3) to 0, libcurl resets the request type to the default to disable the POST. Typically that means gets reset to GET. Instead you should set a new request type explicitly as described above.

DEFAULT
0, disabled

PROTOCOLS
This functionality affects http only

EXAMPLE
int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    CURLcode result;
    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/foo.bin");
    curl_easy_setopt(curl, CURLOPT_POST, 1L);

    /* set up the read callback with CURLOPT_READFUNCTION */

    result = curl_easy_perform(curl);

    curl_easy_cleanup(curl);
  }
}

AVAILABILITY
Added in curl 7.1

RETURN VALUE
curl_easy_setopt(3) returns a CURLcode indicating success or error.

CURLE_OK (0) means everything was OK, non-zero means an error occurred, see libcurl-errors(3).

SEE ALSO
CURLOPT_HTTPPOST(3), CURLOPT_POSTFIELDS(3), CURLOPT_UPLOAD(3)