Question

I am trying to write a C program which is aware of the control / alt / shift key being pressed down. I found something that provides this functionality in Java, but that’s not helping me too much.

void CMousepresentView::OnDraw(CDC* pDC)
{
int shiftValue=::GetKeyState(VK_SHIFT);
if(!shiftValue)
pDC->TextOut(0,50,"Shift not pressed");
else
pDC->TextOut(0,50,"Shift pressed");

int ctrlValue=::GetKeyState(VK_CONTROL);
if(!ctrlValue)
pDC->TextOut(0,100,"Ctrl not pressed");
else
pDC->TextOut(0,100,"Ctrl pressed");
}

So what I have so far is quite rudimentary but I must start somewhere. It doesn’t work though, at all.

#include <stdio.h>
#include <ctype.h>

int main(void)
{
  char ch;

  do {
    ch = getchar();
    putchar(ch);
  } while(iscntrl(ch));
  return 0;
}

I was hoping that iscntrl would at least give me some reaction from the system to start debugging and identifying the control sequence keypresses. No such luck.

If I could see an example that outputs “control is pressed / control is released”, I could probably figure out the rest.

Update:
Have had some progress with this http://www.thelinuxdaily.com/2010/05/grab-raw-keyboard-input-from-event-device-node-devinputevent/

Update:

I think the answer is in using xlib. Thanks everyone.

Answer 1

You can not check for the silent keys in a console program, not just those keys. If using something like ncurses you might get them as modifiers on other keys.

If you want to make a program with a graphical user interface, it’s not a problem. Qt is a popular framework for that. Check the documentation for the framework you select.