C語言是一門面向過程的編程語言，通常被用來編寫系統(tǒng)軟件。在C語言中，如何調(diào)用API接口并解析返回的JSON格式數(shù)據(jù)呢？下面我們通過一個(gè)小例子來講解。

#include <stdio.h>
#include <stdlib.h>
#include <curl/curl.h>
#include <jansson.h>
struct MemoryStruct {
char *memory;
size_t size;
};
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) {
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(void) {
CURL *curl;
CURLcode res;
struct MemoryStruct chunk;
chunk.memory = malloc(1);
chunk.size = 0;
curl = curl_easy_init();
if (curl) {
curl_easy_setopt(curl, CURLOPT_URL, "https://api.github.com/users/github");
curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, WriteMemoryCallback);
curl_easy_setopt(curl, CURLOPT_WRITEDATA, (void *)&chunk);
res = curl_easy_perform(curl);
if (res != CURLE_OK) {
fprintf(stderr, "curl_easy_perform() failed: %s\n",
curl_easy_strerror(res));
}
else {
printf("%lu bytes retrieved\n", (unsigned long)chunk.size);
json_error_t error;
json_t *root;
root = json_loads(chunk.memory, 0, &error);
if (!root) {
printf("error: on line %d: %s\n", error.line, error.text);
return 1;
}
const char *name;
json_unpack(root, "{s:s}", "name", &name);
printf("name: %s\n", name);
json_decref(root);
}
curl_easy_cleanup(curl);
}
free(chunk.memory);
return 0;
}

在代碼中，我們使用curl庫實(shí)現(xiàn)HTTP請(qǐng)求，并將返回的數(shù)據(jù)保存到內(nèi)存中。然后，我們使用jansson庫解析JSON數(shù)據(jù)，并提取出name屬性的值。

以上就是通過C語言調(diào)用API接口并解析JSON數(shù)據(jù)的示例。希望這樣的例子能夠幫助您更好地理解C語言的相關(guān)知識(shí)。