I have the following function that I am using to initialize a HANDLE to a serial port

int initSerialPort(HANDLE* hSerialPort, string portName){
    *hSerialPort = CreateFile(
        _T(portName),
        GENERIC_READ | GENERIC_WRITE,
        0,
        0,
        OPEN_EXISTING,
        FILE_ATTRIBUTE_NORMAL,
        0
    );

    return 0;
}

I want to be able to hand this function a string as a parameter. When I use

_T("COM1"),

as the parameter it works, however, when I try to hand a string in I get an error “Lportname is undefined”.

How can I easily do this, and why am I getting this error?