String 下载字符串C++；返回空

我一直在使用这个在互联网上找到的downloadstring函数，但它一直没有返回任何内容。有什么想法吗

std::string replaceAll(std::string subject, const std::string& search,
    const std::string& replace) {
    size_t pos = 0;
    while ((pos = subject.find(search, pos)) != std::string::npos) {
        subject.replace(pos, search.length(), replace);
        pos += replace.length();
    }
    return subject;
}

std::string DownloadString(std::string URL) {
    HINTERNET interwebs = InternetOpenA("Mozilla/5.0", INTERNET_OPEN_TYPE_DIRECT, NULL, NULL, NULL);
    HINTERNET urlFile;
    std::string rtn;
    if (interwebs) {
        urlFile = InternetOpenUrlA(interwebs, URL.c_str(), NULL, NULL, NULL, NULL);
        if (urlFile) {
            char buffer[2000];
            DWORD bytesRead;
            do {
                InternetReadFile(urlFile, buffer, 2000, &bytesRead);
                rtn.append(buffer, bytesRead);
                memset(buffer, 0, 2000);
            } while (bytesRead);
            InternetCloseHandle(interwebs);
            InternetCloseHandle(urlFile);
            std::string p = replaceAll(rtn, "|n", "\r\n");
            return p;
        }
    }
    InternetCloseHandle(interwebs);
    std::string p = replaceAll(rtn, "|n", "\r\n");
    return p;
}

std:：string str=DownloadString（“127.0.0.1/document.txt”）；
标准：：cout
std::string str = DownloadString("127.0.0.1/document.txt");
std::cout << str << std::endl;