Frustrating problem with QextSerialPort write()

[calhal]

while (inpSt.compare("quit") != 0)
    {
        std::getline(std::cin, inpSt);
        std::cerr << serialPort->write(inpSt.c_str());
        std::cerr << "Sent command: " << inpSt << std::endl;
    }

while (inpSt.compare("quit") != 0)
    {
        std::getline(std::cin, inpSt);
        std::cerr << serialPort->write(inpSt.c_str());
        std::cerr << "Sent command: " << inpSt << std::endl;
    }

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What do you get from this on stderr?
And am I missing something or you're not opening the port in your code?
The rest as wysota wrote

[kachofool]

Thanks to all for the replies.

@wysota
Emit seems to be working. I downloaded the latest source from the project website and read under their 'issues' section that event based I/O had been implemented (in POSIX at least, and I'm on linux).

@calhan
For some odd reason (maybe copy/paste) the line of code for opening the port isn't in my original post. The line is actually

//	open serial port
    port->open(QIODevice::ReadWrite);

//	open serial port
    port->open(QIODevice::ReadWrite);

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And it's right after I set up the port parameters, before I launch the helper threads.

The output of stderr is the expected number of characters I write. An example of a command string I'm outputting to the device is "1 RN".
The return value of the write command is 4.

EDIT:
The issue was with the command string I was sending to the device. The string needed to be terminated with *both* newline and carriage return characters... everything seems okay now. Thanks!

EDIT (EDIT):
@kuzulis: I've tried your library and it works as well (since the error was on my part). Thank you for providing the community with a Qt serial i/o library, however I want to agree with what calhan said in that you've advertised your library often (already in another thread of mine!) without really replying to the question.