以下是C++實現HTTPClient的基本步驟：

1. 包含必要的頭文件：

#include <iostream>
#include <string>
#include <sstream>
#include <curl/curl.h>

2. 定義HTTPClient類：

class HTTPClient {
public:
    HTTPClient();
    ~HTTPClient();
    std::string get(const std::string& url);
private:
    static size_t writeCallback(void* contents, size_t size, size_t nmemb, void* userp);
    CURL* curl;
};

3. 實現HTTPClient類的構造函數和析構函數：

HTTPClient::HTTPClient() {
    curl_global_init(CURL_GLOBAL_ALL);
    curl = curl_easy_init();
}

HTTPClient::~HTTPClient() {
    curl_easy_cleanup(curl);
    curl_global_cleanup();
}

4. 實現HTTPClient類的get方法：

std::string HTTPClient::get(const std::string& url) {
    std::string response;
    if(curl) {
        curl_easy_setopt(curl, CURLOPT_URL, url.c_str());
        curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, writeCallback);
        curl_easy_setopt(curl, CURLOPT_WRITEDATA, &response);
        CURLcode res = curl_easy_perform(curl);
        if(res != CURLE_OK) {
            std::cerr << "Error during GET request: " << curl_easy_strerror(res) << std::endl;
        }
    }
    return response;
}

5. 實現HTTPClient類的靜態寫回調函數：

size_t HTTPClient::writeCallback(void* contents, size_t size, size_t nmemb, void* userp) {
    size_t realsize = size * nmemb;
    std::string* response = (std::string*)userp;
    response->append((char*)contents, realsize);
    return realsize;
}

6. 在主函數中使用HTTPClient類實現HTTP GET請求：

int main() {
    HTTPClient client;
    std::string url = "https://jsonplaceholder.typicode.com/posts/1";
    std::string response = client.get(url);
    std::cout << "Response: " << response << std::endl;
    return 0;
}

通過以上步驟，我們可以實現一個簡單的C++ HTTPClient，可以用來發送GET請求并獲取響應數據。