現在，越來越多的網絡應用程序需要與服務器端進行交互。而JSON（JavaScript Object Notation）被廣泛應用于這種交互方式中。

C JSON是一種用于解析和生成JSON數據的C語言庫。它的基本結構如下：

typedef struct json_object_struct {
enum json_type o_type;
union data {
struct array_list* array;
struct lh_table* object;
char* string;
double dbl;
int64_t int64;
uint64_t uint64;
int boolean;
} o;
} json_object;

通過使用C JSON，我們可以通過HTTP請求向服務器端發送JSON數據，并且解析服務器端返回的JSON數據。具體代碼實現如下：

#include "json.h"
#include#includestatic size_t WriteMemoryCallback(void* contents, size_t size, size_t nmemb, void* userp) {
size_t realsize = size * nmemb;
char* ptr = realloc(userp, strlen(userp) + realsize + 1);
if (ptr == NULL) {
printf("Not enough memory\n");
return 0;
}
memcpy(ptr + strlen(ptr), contents, realsize);
*(ptr + strlen(ptr) + realsize) = '\0';
return realsize;
}
int main(void) {
CURL* curl_handle;
CURLcode res;
char* read_data = (char*)malloc(1);
*read_data = '\0';
json_object* read_obj;
char* post_data = "{ \
\"name\": \"John Smith\", \
\"age\": 25, \
\"address\": \"Los Angeles, CA 90001\" \
}";
curl_global_init(CURL_GLOBAL_DEFAULT);
curl_handle = curl_easy_init();
if (curl_handle) {
curl_easy_setopt(curl_handle, CURLOPT_URL, "http://example.com");
curl_easy_setopt(curl_handle, CURLOPT_POSTFIELDS, post_data);
curl_easy_setopt(curl_handle, CURLOPT_WRITEFUNCTION, WriteMemoryCallback);
curl_easy_setopt(curl_handle, CURLOPT_WRITEDATA, (void*)read_data);
res = curl_easy_perform(curl_handle);
if (res != CURLE_OK) {
fprintf(stderr, "curl_easy_perform() failed: %s\n", curl_easy_strerror(res));
}
else {
read_obj = json_tokener_parse(read_data);
printf("name: %s\n", json_object_get_string(json_object_object_get(read_obj, "name")));
printf("age: %d\n", json_object_get_int(json_object_object_get(read_obj, "age")));
printf("address: %s\n", json_object_get_string(json_object_object_get(read_obj, "address")));
}
curl_easy_cleanup(curl_handle);
}
curl_global_cleanup();
return 0;
}

上面的代碼首先使用cURL庫向服務器端發送HTTP請求，將post_data作為數據發送。同時，將服務器響應的數據通過WriteMemoryCallback函數寫入read_data中，最后使用json_tokener_parse函數解析read_data，獲取服務器返回的JSON數據。在這里，我們以"name"、"age"、"address"三個字段的值作為樣例進行解析，并打印出來。