c - 使用 libcurl 和 C 访问 Twitter Streaming API

Question

我正在尝试用 C 编写一个程序，它将从流式 API 中获取每条推文并将其存储在数据库中。但是，我无法让它工作，我正在使用以下代码:

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


size_t callback_func(void *ptr, size_t size, size_t count, void *stream) {
  /* ptr - your string variable.
  stream - data chuck you received */
printf("res %s \n \n", (char*)ptr); //prints chunck of data for each call.

}

int main(void)
{
  CURL *curl;
  CURLcode res;

  curl = curl_easy_init();
  if(curl) {
   curl_easy_setopt(curl, CURLOPT_URL, "http://google.com/");
    //curl_easy_setopt(curl, CURLOPT_USERPWD, "JEggers2:password");
    curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, callback_func);
    curl_easy_perform(curl);

    /* always cleanup */ 
     curl_easy_cleanup(curl);


  }


  return 0;
}

此代码仅输出一条 JSON 格式的推文。我究竟做错了什么？谢谢

Answer 1

问题是 callback_func 没有返回任何东西。

根据spec ，如果读取成功，您应该返回 size。

Function pointer that should match the following prototype: size_t function( void *ptr, size_t size, size_t nmemb, void *userdata); This function gets called by libcurl as soon as there is data received that needs to be saved. The size of the data pointed to by ptr is size multiplied with nmemb, it will not be zero terminated. Return the number of bytes actually taken care of. If that amount differs from the amount passed to your function, it'll signal an error to the library. This will abort the transfer and return CURLE_WRITE_ERROR.