libcurl将分享链接转化成视频链接

libcurl本身并不能将分享链接转化成视频链接，但是可以通过调用一些第三方API来实现这个功能。以下是一个示例代码，可以使用libcurl和Google的YouTube Data API将分享链接转换为视频ID并获取视频信息：

#include <stdio.h>
#include <curl/curl.h>
#include <json-c/json.h>

size_t write_callback(char *ptr, size_t size, size_t nmemb, void *userdata) {
    return fwrite(ptr, size, nmemb, (FILE*)userdata);
}

int main(int argc, char **argv) {
    if (argc < 2) {
        printf("Usage: %s <share_link>\n", argv[0]);
        return 1;
    }

    char url[256];
    sprintf(url, "https://www.googleapis.com/youtube/v3/videos?part=snippet&id=%s&key=YOUR_API_KEY", argv[1]);

    CURL *curl = curl_easy_init();
    if (!curl) {
        printf("Failed to initialize libcurl.\n");
        return 1;
    }

    FILE *fp = fopen("response.json", "w");
    if (!fp) {
        printf("Failed to open file for writing.\n");
        return 1;
    }

    curl_easy_setopt(curl, CURLOPT_URL, url);
    curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1L);
    curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, write_callback);
    curl_easy_setopt(curl, CURLOPT_WRITEDATA, fp);

    CURLcode res = curl_easy_perform(curl);
    if (res != CURLE_OK) {
        printf("Failed to perform request: %s\n", curl_easy_strerror(res));
        return 1;
    }

    fclose(fp);

    fp = fopen("response.json", "r");
    if (!fp) {
        printf("Failed to open file for reading.\n");
        return 1;
    }

    char buffer[1024];
    fread(buffer, 1, 1024, fp);
    fclose(fp);

    json_object *root = json_tokener_parse(buffer);
    if (!root) {
        printf("Failed to parse JSON response.\n");
        return 1;
    }

    json_object *items = NULL;
    if (json_object_object_get_ex(root, "items", &items)) {
        if (json_object_get_type(items) == json_type_array) {
            json_object *item = json_object_array_get_idx(items, 0);
            json_object *snippet = NULL;
            if (json_object_object_get_ex(item, "snippet", &snippet)) {
                json_object *title = NULL;
                if (json_object_object_get_ex(snippet, "title", &title)) {
                    printf("Title: %s\n", json_object_get_string(title));
                }
            }
        }
    }

    json_object_put(root);

    curl_easy_cleanup(curl);

    return 0;
}

在这个示例中，我们使用了Google的YouTube Data API来获取视频信息。您需要在Google Cloud Console中创建一个项目并启用YouTube Data API，然后为该项目创建一个API密钥，并将密钥替换为代码中的“YOUR_API_KEY”。