如何用c语言，curl，cjson获取codeforces api

Codeforces API提供了RESTful API，可以使用curl和cjson库来获取API数据。以下是一个示例程序，该程序使用curl和cjson库来获取Codeforces API数据：

#include <stdio.h>
#include <curl/curl.h>
#include <cjson/cJSON.h>

#define API_URL "https://codeforces.com/api/user.rating?handle="

struct MemoryStruct {
  char *memory;
  size_t size;
};

// 回调函数，用于处理curl获取到的数据
static size_t WriteMemoryCallback(void *contents, size_t size, size_t nmemb, void *userp) {
  size_t realsize = size * nmemb;
  struct MemoryStruct *mem = (struct MemoryStruct *)userp;

  mem->memory = realloc(mem->memory, mem->size + realsize + 1);
  if (mem->memory == NULL) {
    /* out of memory! */
    printf("not enough memory (realloc returned NULL)\n");
    return 0;
  }

  memcpy(&(mem->memory[mem->size]), contents, realsize);
  mem->size += realsize;
  mem->memory[mem->size] = 0;

  return realsize;
}

int main(int argc, char **argv) {
  CURL *curl_handle;
  CURLcode res;

  struct MemoryStruct chunk;

  chunk.memory = malloc(1);  /* will be grown as needed by the realloc above */
  chunk.size = 0;            /* no data at this point */

  if (argc < 2) {
    printf("Usage: %s <handle>\n", argv[0]);
    exit(1);
  }

  char url[1024];
  snprintf(url, sizeof(url), "%s%s", API_URL, argv[1]);

  curl_global_init(CURL_GLOBAL_ALL);

  curl_handle = curl_easy_init();
  curl_easy_setopt(curl_handle, CURLOPT_URL, url);
  curl_easy_setopt(curl_handle, CURLOPT_WRITEFUNCTION, WriteMemoryCallback);
  curl_easy_setopt(curl_handle, CURLOPT_WRITEDATA, (void *)&chunk);

  res = curl_easy_perform(curl_handle);

  if (res != CURLE_OK) {
    fprintf(stderr, "curl_easy_perform() failed: %s\n", curl_easy_strerror(res));
    exit(1);
  }

  curl_easy_cleanup(curl_handle);

  cJSON *json = cJSON_Parse(chunk.memory);

  if (json == NULL) {
    printf("Error parsing JSON data.\n");
    exit(1);
  }

  cJSON *result = cJSON_GetObjectItemCaseSensitive(json, "result");
  
  if (cJSON_IsArray(result)) {
    int count = cJSON_GetArraySize(result);
    for (int i = 0; i < count; i++) {
      cJSON *item = cJSON_GetArrayItem(result, i);
      cJSON *contestId = cJSON_GetObjectItemCaseSensitive(item, "contestId");
      cJSON *contestName = cJSON_GetObjectItemCaseSensitive(item, "contestName");
      cJSON *rank = cJSON_GetObjectItemCaseSensitive(item, "rank");
      cJSON *ratingChange = cJSON_GetObjectItemCaseSensitive(item, "newRating") - cJSON_GetObjectItemCaseSensitive(item, "oldRating");
      printf("Contest %d: %s (Rank: %d, Rating Change: %d)\n", contestId->valueint, contestName->valuestring, rank->valueint, ratingChange->valueint);
    }
  }

  cJSON_Delete(json);
  free(chunk.memory);
  
  return 0;
}

这个程序会获取指定Codeforces用户的比赛评级历史记录，并输出到控制台上。你可以根据自己的需要修改代码，以便访问不同的Codeforces API端点和处理不同的数据。