c++ - 多次调用 CreateFileA 时为 INVALID_HANDLE_VALUE

Question

我正在使用 CreateFileA，我第一次调用它时，它按预期工作。但是当我第二次调用它时，它返回句柄 INVALID_HANDLE_VALUE。可能是什么问题呢？仅供引用，每次我需要检查我的 USB 设备是否已连接时我都会调用它..

int port = 500;
char port_name [MAX_CAR] = {0};

sprintf_s (port_name, MAX_CAR, "\\\\.\\COM%d", port);

com->id = CreateFileA (port_name,
                       GENERIC_READ | GENERIC_WRITE,
                       0,
                       NULL,
                       OPEN_EXISTING,
                       FILE_FLAG_OVERLAPPED,
                       NULL);

编辑:我确实尝试像 CloseHandle(com->id); 这样使用 CloseHandle；但这没有帮助。

Answer 1

来自documentation :

When an application is finished using the object handle returned by CreateFile, use the CloseHandle function to close the handle. This not only frees up system resources, but can have wider influence on things like sharing the file or device and committing data to disk. Specifics are noted within this topic as appropriate.