下面我們來看一下如何使用c語言發送json http請求。

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <curl/curl.h>
static size_t write_callback(char *data, size_t size, size_t nmemb, void *userdata) {
printf("%s", data);
return size * nmemb;
}
int main() {
CURL *curl;
CURLcode res;
curl = curl_easy_init();
if (curl) {
const char *url = "https://jsonplaceholder.typicode.com/posts";
const char *json_data = "{\"title\":\"foo\",\"body\":\"bar\",\"userId\":1}";
struct curl_slist *headers = NULL;
headers = curl_slist_append(headers, "Content-Type: application/json");
curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headers);
curl_easy_setopt(curl, CURLOPT_URL, url);
curl_easy_setopt(curl, CURLOPT_POSTFIELDS, json_data);
curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, write_callback);
res = curl_easy_perform(curl);
if (res != CURLE_OK) {
printf("curl_easy_perform() failed: %s\n", curl_easy_strerror(res));
}
curl_easy_cleanup(curl);
}
return EXIT_SUCCESS;
}

上述代碼中，我們使用了curl庫來發送http請求。首先我們初始化了一個curl對象，然后設置了請求url和請求體(json格式)。接著我們設置請求頭部，其中Content-Type為application/json。最后我們設置了回調函數來接收響應結果并打印輸出。