C++ QueryDosDeviceA() return 0 但 COMX 已连接

Question

所以我正在执行一个函数来检索使用 QueryDosDeviceA

连接到系统的所有 COM 串行端口名称

我尝试将 CreatFileA 与 "\\.\COM6" 一起使用，但没有出现任何错误。但是 QueryDosDeviceA 与 "COM6" 或 "\\.\COM6"

Function.cpp

std::vector<std::string> SerialPort::_SerialList()
{
    std::vector<std::string> serialList;
    std::string COMName("\\.\COM"), queryName(COMName); //also tried with COMName("COM")
    CHAR bufferTragetPath[5000];
    std::string tmp;
    DWORD path_size(0);

    //test each COM name to get the one used by the system
    for (int i(0); i < 255; i++)
    {
        queryName = COMName + std::to_string(i);
        //Query the path of the COMName
        path_size = QueryDosDeviceA((LPCSTR)&queryName, (LPSTR)&bufferTragetPath, 5000);

        std::cout << std::endl << "Path for " << queryName << ":" << path_size;

        if (path_size != 0) {
            std::cout << "pushing..." << queryName << " on " << bufferTragetPath << std::endl;
            serialList.push_back(queryName);
        }
    }
    return serialList;
}

这是输出：

Path for \.\COM0:0
Path for \.\COM1:0
Path for \.\COM2:0
Path for \.\COM3:0
Path for \.\COM4:0
Path for \.\COM5:0
Path for \.\COM6:0
Path for \.\COM7:0
Path for \.\COM8:0
Path for \.\COM9:0
...
Path for \.\COM253:0
Path for \.\COM254:0Port name: \.\COM6
Hello World !

所以除了 COM6 端口可以被 CreateFileA 使用之外什么也没找到

Answer 1

感谢@user253751、@JohnnyMopp、@dresscherjm 还有@RemyLebeau

这是包含解决方案的代码：

std::vector<std::string> SerialPort::_SerialList()
{
    std::vector<std::string> serialList;
    std::string COMName("COM"), queryName("");
    CHAR bufferTragetPath[5000];
    std::string tmp;
    DWORD path_size(0);

    //test each COM name to get the one used by the system and get his description name
    for (int i(0); i < 255; i++)
    {
        queryName = COMName + std::to_string(i);

        //Query the path of the COMName
        path_size = QueryDosDeviceA(queryName.c_str(), bufferTragetPath, 5000);
        std::cout << std::endl << "Path for " << queryName << ":" << path_size << "   " << queryName;
        if (path_size != 0) {
            std::cout << "pushing..." << queryName << " on " << bufferTragetPath << std::endl;
            serialList.push_back(tmp);
        }
    }
    return serialList;
}

基本上我将 queryName 的转换从字符串更改为 LPCSTR

//LPCSTR => Long Pointer Const String(= const char)
queryName.c_str() //return queryName as const char*

我还从 bufferTragetPath 中删除了一个无用的转换

//from 
(LPSTR)&bufferTragetPath
//to
bufferTragetPath //cause bufferTragetPath is char *

C++ QueryDosDeviceA() return 0 但 COMX 已连接

C++ QueryDosDeviceA() return 0 but COMX is connected

c++

winapi

serial-port