struct curl_slist *headers=NULL; // init to NULL is important

headers = curl_slist_append(headers, "Accept: application/json");
headers = curl_slist_append(headers, "Content-Type: application/json");
headers = curl_slist_append(headers, "charsets: utf-8");

curl = curl_easy_init();
if(curl) {
    curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L);
    curl_easy_setopt(curl, CURLOPT_URL, "https://m360-prototype.herokuapp.com/sessions.json");
    curl_easy_setopt(curl, CURLOPT_POSTFIELDS, "username=testuser&password=12345");

    curl_easy_setopt(curl, CURLOPT_HTTPGET,1);
    curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headers);
    res = curl_easy_perform(curl);

    if(CURLE_OK == res) {
        char *ct;
        /* ask for the content-type */
        res = curl_easy_getinfo(curl, CURLINFO_CONTENT_TYPE, &ct);
        if((CURLE_OK == res) && ct)
            printf("We received Content-Type: %sn", ct);
    }
}

std::string data = "username=testuser&password=12345";
curl_easy_setopt(curl, CURLOPT_POSTFIELDS, data.c_str());
curl_easy_setopt(curl, CURLOPT_POSTFIELDSIZE, data.length());
curl_easy_setopt(curl, CURLOPT_POST, 1);

std::string data = "{"username":"testuser","password":"12345"}";
curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, 0);  // for --insecure option
curl_easy_setopt(curl, CURLOPT_POSTFIELDS, data.c_str());
curl_easy_setopt(curl, CURLOPT_POSTFIELDSIZE, data.length());
curl_easy_setopt(curl, CURLOPT_POST, 1);

CURLcode ret;
  CURL *hnd;
  struct curl_slist *slist1;
  std::string jsonstr = "{"username":"bob","password":"12345"}";

  slist1 = NULL;
  slist1 = curl_slist_append(slist1, "Content-Type: application/json");

  hnd = curl_easy_init();
  curl_easy_setopt(hnd, CURLOPT_URL, "http://u/r/l");
  curl_easy_setopt(hnd, CURLOPT_NOPROGRESS, 1L);
  curl_easy_setopt(hnd, CURLOPT_POSTFIELDS, jsonstr.c_str());
  curl_easy_setopt(hnd, CURLOPT_USERAGENT, "curl/7.38.0");
  curl_easy_setopt(hnd, CURLOPT_HTTPHEADER, slist1);
  curl_easy_setopt(hnd, CURLOPT_MAXREDIRS, 50L);
  curl_easy_setopt(hnd, CURLOPT_CUSTOMREQUEST, "POST");
  curl_easy_setopt(hnd, CURLOPT_TCP_KEEPALIVE, 1L);

  ret = curl_easy_perform(hnd);

  curl_easy_cleanup(hnd);
  hnd = NULL;
  curl_slist_free_all(slist1);
  slist1 = NULL;