How do I POST a buffer of JSON using libcurl?

Question

My C++ program currently invokes curl through a pipe (popen(\"curl ...\")) to POST a file of JSON data to a web server. This has obvious performance limitations due

Answer 1

You can use CURLOPT_POSTFIELDS:

CURL *curl = curl_easy_init();

curl_easy_setopt(curl, CURLOPT_URL, "http://example.com/api/endpoint");
curl_easy_setopt(curl, CURLOPT_POSTFIELDS, "{\"hi\" : \"there\"}");

curl_easy_perform(curl);

Since CURLOPT_POSTFIELDS does not modify the payload in any way, it is very convenient for POSTing JSON data. Also note that, when CURLOPT_POSTFIELDS is supplied, it automatically enables CURLOPT_POST so there is no need to provide CURLOPT_POST in the request.