curl向web服务器发送json数据

c++使用libcurl：

 /*
  *g++ demo.cpp  -g -Wall -lcurl
  */

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

 int getUrl(const char* filename)
 {
     CURL* curl;
     CURLcode res;
     FILE* fp;
     if((fp=fopen(filename, "w"))==NULL){
         return -;
     }
     struct curl_slist *headers = NULL;
     headers = curl_slist_append(headers, "Accept:Agent-007");
     curl = curl_easy_init();
     if(curl){
         curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headers);
         curl_easy_setopt(curl, CURLOPT_URL, "http://www.baidu.com");
         curl_easy_setopt(curl, CURLOPT_WRITEDATA, fp);
         curl_easy_setopt(curl, CURLOPT_HEADERDATA, fp);

         //0: success, other: failure
         res = curl_easy_perform(curl);
         if(res != ){
             std::cout <<"error:"<<curl_easy_strerror(res) << std::endl;
         }
         curl_slist_free_all(headers);
         curl_easy_cleanup(curl);
         fclose(fp);
     }
     return res;
 }

 /*
 int postUrl(const char* filename)
 {
     CURL* curl;
     CURLcode res;
     FILE* fp;

     if((fp=fopen(filename, "w"))==NULL){
         return 1;
     }
     curl = curl_easy_init();
     if(curl){

     }
 }
 */

 //typedef  int  (* func)(int,  int);
 typedef  size_t (*cb_func)(void*, size_t, size_t, void*);
 size_t write_data(void *buffer, size_t size, size_t nmemb, void *userp) {
     FILE *fptr = (FILE*)userp;
     fwrite(buffer, size, nmemb, fptr);
     return size*nmemb;
 }

 int PostData(const char* postdata, const char* url,
              cb_func write_data, void* fptr)
 //int PostData(const char* postdata, const char* url)
 {
     CURL* curl = NULL;
     CURLcode res;
     char tmp[] = {};
     struct curl_slist* headers = NULL;
     if(!url){
         return -;
     }
     std::cout <<"send data url:" << url << std::endl;
     snprintf(tmp, sizeof(tmp), "Content-Length: %d", (int)strlen(postdata));
     std::cout <<"Content-Length: " << tmp << std::endl;
     headers = curl_slist_append(headers, "Accept: application/json");
     headers = curl_slist_append(headers, "Content-Type: application/json");
     headers = curl_slist_append(headers, "charset: utf-8");
     headers = curl_slist_append(headers, tmp);

     curl_global_init(CURL_GLOBAL_ALL);
     curl = curl_easy_init();
     if(curl){
         curl_easy_setopt(curl, CURLOPT_URL,url);
         curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headers);
         curl_easy_setopt(curl, CURLOPT_TIMEOUT, ); //超时时间1s
         curl_easy_setopt(curl, CURLOPT_POST, 1L);
         curl_easy_setopt(curl, CURLOPT_POSTFIELDS, postdata);
         curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, write_data);
         curl_easy_setopt(curl, CURLOPT_WRITEDATA, fptr);
         //curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L);   //debug
         res = curl_easy_perform(curl);
         if(res!=){
             std::cout<<"error no:"<<curl_easy_strerror(res)<<std::endl;
         }
         curl_slist_free_all(headers);
         curl_easy_cleanup(curl);
         return res;
     }else{
         curl_slist_free_all(headers);
         return -;
     }
 }

 int main()
 {
     const char* tt = "./aa.out";
     int aa =  getUrl(tt);
     std::cout << "return :" << aa << std::endl;
     FILE* fptr;
     if((fptr=fopen("./result", "w"))==NULL){
         std::cout << "file open error" << std::endl;
         exit();
     }

     const char* jsondata = "{\"usrname\": \"cp\", \"passwd\": \"test\"}";
      const char* url = "http://192.168.2.163:8080/mystorage/mytest.php";
     aa = PostData(jsondata, url, write_data, fptr);
     return ;
 }