Using gets() in a thread

[macgowan]

Hi --

I have a Win32 console application that takes user input using gets(). When the user presses the ESC key I would like to exit the current 'thing' the user is doing.

gets() seems to 'take over' until the user presses the RETURN key.

I am attempting to create two threads. The first thread is a UI thread that will do the get() functions and the second thread will monitor keypresses or messages for the ESC key.

I am having problems with thread priority. I have tryed some different priority settings and either get the user input and not the ESC key - or I get the ESC key and there is not user input.

Any comments ?
Thanks,
Chris


///////////////////////////////////////////////
// Starting the threads in the main()

// Create the monitor thread
Threadhandle = CreateThread(NULL, 0, ThreadprocESCMonitor, 0, 0, &Threadid);

// Set the priority
SetThreadPriority(Threadhandle, THREAD_PRIORITY_ABOVE_NORMAL);

// create the user interface thread
Threadhandle = CreateThread(NULL, 0, ThreadprocUserInterface, 0, 0, &Threadid);

// Set the priority
SetThreadPriority(Threadhandle, THREAD_PRIORITY_HIGHEST);


///////////////////////////////////////////////
// Thread ThreadprocUserInterface
DWORD WINAPI ThreadprocUserInterface(LPVOID lpParameter)
{
while (bLoop)
{
if (gfkbhit())
{
// The gets() are in the HandleCommands Function
HandleCommand(getkey());
}
}
return 0;
}



///////////////////////////////////////////////
// Thread ThreadprocESCMonitor
DWORD WINAPI ThreadprocESCMonitor(LPVOID lpParameter)
{
while (bLoop)
{
// Test for a key press
if (gfkbhit())
{
if (getkey() == ESC)
{
Beep(1000, 10);
}
}
}
return 0;
}

[kuphryn]

What is "ESC" in this line?

if (getkey() == ESC)

VK_ESCAPE

Kuphryn

[j0nas]

gets() blocks until return is pressed.

CreateThread() isn't good to use together with C run-time library functions (like gets(), printf() etc). You should be using _beginthread or _beginthreadex instead of CreateThread (and compile with /MD).

I don't know how the keyboard buffer queue is handled, but I would maybe create my on input function (similar to gets()) that doesn't block and then skip the ESC key check in the other thread. I think you have made it more complicated than it really is.

[Bassman]

Or, your one thread can grab _all_ the keystrokes including ESC, and use Create/Reset/SetEvent() and WaitForSingleObject() to signal the other thread that ESC has been pressed.

That way you don't have the two threads fighting for the input buffer and your second thread doesn't have to spin forever. (Or your first one, either, since you'll now be free to use blocking input methods in that thread.)

HANDLE hESC = CreateEvent(NULL, TRUE, FALSE, NULL);

...

DWORD WINAPI ThreadprocUserInterface(LPVOID lpParameter)
{
...
  if (getkey() == ESC)
     SetEvent(hESC);
...
}

DWORD WINAPI ThreadprocESCMonitor(LPVOID lpParameter)
{
...
WaitForSingleObject(hESC, INFINITE);
// ESC has been pressed!
...
}

HTH,
Bassman