converting CURL command line to libcurl code

[rozick1]

Hi

I can successfully POST data using the libcurl utility:

curl -v -X POST -d "{\"temperature\": 25}" http://localhost:8080/api/v1/MY_ACCESS_TOKEN/telemetry --header "Content-Type:application/json" 

I would like to post exactly the same data using libcurl. My code is as follows:

#include <iostream>
#include <curl/curl.h>

#define HOST_NAME "http://localhost:8080/api/v1/"
#define ACCESS_TOKEN "MY_ACCESS_TOKEN"
#define HOST_SUFFIX "/telemetry"

#define JSON_DATA "{\"temperature\": 25}"

int main()
{
   
  CURL *curl;
  CURLcode res;
 
  curl_global_init(CURL_GLOBAL_ALL);
 
  /* get a curl handle */
  curl = curl_easy_init();
  if(curl) {

    std::string myURL = std::string(HOST_NAME) += std::string(ACCESS_TOKEN) += std::string(HOST_SUFFIX);  // build the url
    curl_easy_setopt(curl, CURLOPT_URL, myURL.c_str() ); // set the url

    struct curl_slist *headers = NULL;
    headers = curl_slist_append(headers, "Content-Type: application/json"); // json header

    curl_easy_setopt(curl, CURLOPT_CUSTOMREQUEST, "POST");
    curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headers);

    /* Now specify the POST data */
    curl_easy_setopt(curl, CURLOPT_POSTFIELDS, JSON_DATA);
 
    /* Perform the request, res will get the return code *
  curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L);

    res = curl_easy_perform(curl);
    /* Check for errors */
    if(res != CURLE_OK)
      fprintf(stderr, "curl_easy_perform() failed: %s\n",
              curl_easy_strerror(res));
 
    /* always cleanup */
    curl_easy_cleanup(curl);
  }
  curl_global_cleanup();
  return 0;
  
  return 0;
}

This code generates the following output:

curl_easy_perform() failed: Unknown error

Does anyone know what I might be doing wrong?

Thanks very much

[dutch]

Try adding a / at the end of HOST_SUFFIX

#define HOST_SUFFIX "/telemetry/" 

Also, you should be using + not += when constructing your url (although it won't make a difference in the final url).

And maybe comment this out:

curl_easy_setopt(curl, CURLOPT_CUSTOMREQUEST, "POST");