使用C代码中的curl库连接到wit api url时出错

Question

目的：使用C

使用curl库获取Wit API的响应

源代码：

#include <stdio.h>
#include <string.h>
#include <curl/curl.h>

int main(void)
{
  CURL *curl;
  CURLcode res;
  struct curl_slist *list = NULL;

  static const char *postthis="q=hello";

  curl = curl_easy_init();
  if(curl) {
    curl_easy_setopt(curl, CURLOPT_URL, "https://api.wit.ai/message);

    list = curl_slist_append(list, "Authorization: Bearer $TOKEN");
    curl_easy_setopt(curl, CURLOPT_HTTPHEADER, list);

    curl_easy_setopt(curl, CURLOPT_POSTFIELDS, postthis);

/* if we don't provide POSTFIELDSIZE, libcurl will strlen() by
   itself */ 
   curl_easy_setopt(curl, CURLOPT_POSTFIELDSIZE, (long)strlen(postthis));

/* Perform the request, res will get the return code */ 
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_slist_free_all(list);
   curl_easy_cleanup(curl);
  }
return 0;
}

$ TOKEN是Wit Api的身份验证令牌

错误：验证错误，检查令牌/参数