下面的代码输出的txt文件为空请修改代码：#include iostream#include fstream#include string#include vector#include boostasiohppusing boostasioiptcp; 下载accession号并保存到文件void downloadAccessionNumbersconst stdstring& geneName

#include #include #include #include #include <boost/asio.hpp>

using boost::asio::ip::tcp;

// 下载accession号并保存到文件 void downloadAccessionNumbers(const std::string& geneName, const std::string& outputFile) { try { // 创建IO上下文 boost::asio::io_context io_context;

    // 解析NCBI服务器的IP地址和端口号
    tcp::resolver resolver(io_context);
    tcp::resolver::results_type endpoints = resolver.resolve("www.ncbi.nlm.nih.gov", "http");

    // 创建socket并连接到NCBI服务器
    tcp::socket socket(io_context);
    boost::asio::connect(socket, endpoints);

    // 发送HTTP GET请求
    std::string request = "/bioproject/?term=" + geneName + "&report=docsum&format=text";
    boost::asio::write(socket, boost::asio::buffer("GET " + request + " HTTP/1.1\r\n"
                                                   "Host: www.ncbi.nlm.nih.gov\r\n"
                                                   "Connection: close\r\n\r\n"));

    // 读取服务器响应
    std::ofstream outputFileStream(outputFile);
    std::string response;
    std::vector<char> responseBuffer(1024);
    std::size_t bytesRead = 0;
    boost::system::error_code error;
    do
    {
        bytesRead = socket.read_some(boost::asio::buffer(responseBuffer), error);
        if (error == boost::asio::error::eof)
        {
            break; // 到达文件末尾
        }
        else if (error)
        {
            throw boost::system::system_error(error); // 其他错误
        }
        // 将响应缓冲区中的数据追加到字符串
        response.append(responseBuffer.data(), bytesRead);
    } while (true);

    // 在响应中搜索accession号，并将其写入文件
    size_t found = response.find("ACCESSION ");
    while (found != std::string::npos)
    {
        size_t end = response.find("\n", found);
        std::string accession = response.substr(found + 10, end - found - 10);
        outputFileStream << accession << std::endl;
        found = response.find("ACCESSION ", found + 1);
    }

    // 关闭文件和socket
    outputFileStream.close();
    socket.close();
}
catch (std::exception& e) {
    std::cerr << "Exception: " << e.what() << std::endl;
}

}

int main() { std::string geneName = "phoD"; std::string outputFile = "accession_numbers.txt";

downloadAccessionNumbers(geneName, outputFile);

return 0;

}