getkey?...recognize key depression

[AndBack3]

Does anyone know how to get any key pressed by a user?

ie. in a loop, if user presses

, a variable is incremented, if a user presses,

, a variable is decremented. I also want this loop to continue running whether the user presses a button or not.​

 

[spirou]

I'll give you two function : getc(), getch().

If you need more help there are some example in other thread. Try a search with keyboard in C forums.

 

[Deathwish]

with Getc or Getch wouldnt the program wait untill you would have pressed a key?

i think thats not what he wants, heh. at least thats not what i want i need to let the program run (like the main_loop)

tnx in advance,
Deathwish

 

[spirou]

Here I am.
I hope you can use kbhit(). It doesn't work on UNIX, LINUX and ANSI.

See this simple program which print the code of the Key you pressed.


#include <stdio.h>
#include <conio.h>

int main()
{
char key=0;

while( key != 27 )
{
while( !kbhit() )
{
}
key = getch();
printf(&quot;%d&quot;,key);
}
return 0;
}

 

[AndBack3]

thx for pointing out the kbhit () function

looked around and found out exactly how to use it....for some reason i keep getting the error :implicit declaration of function `int kbhit(...)'


what this means, i have no idea, but i get it when i make my own program, copy yours, or copy others

 

[Deathwish]

There is only 1 little drawback of Kbhit():

This comes directly from the c++ builder help
Note: Do not use this function for Win32s or Win32 GUI applications.

so u cant use it for windows based programs.
Is there a way around this??

 

[spirou]

I agree, kbhit() work only in DOS or command application.
So my previous example work on Win9x an NT4.0 .

But if you're application is within a window, you'll have to learn more about Virtual Key and WNDPROC callback function.

Here is the same example but in a window format :

//-----------------------------------------------------------------------------
#define APPNAME  "GetKey2"
#define APPTITLE "GetKey2"
#include <windows.h>
#include <stdio.h>
#include <time.h>

HWND hWnd;

/* Print the virtual Key Code */
void PrintKey(WPARAM wParam)
{
  HDC pDc;
  RECT rct;
  char msg[10];
  
  sprintf(msg, &quot;%d\n&quot;, wParam );
  pDc = GetDC( hWnd );
  GetClientRect( hWnd, &rct );

  FillRect(pDc, &rct, (HBRUSH)GetStockObject(BLACK_BRUSH)); 

  DrawText( pDc, msg, strlen(msg), &rct, DT_LEFT	| DT_TOP);
 
  ReleaseDC(hWnd,pDc);
}

LRESULT CALLBACK WindowProc (HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
	switch (message)
	{
	case WM_KEYDOWN:
    PrintKey( wParam );
 	  break;

	case WM_DESTROY:
		PostQuitMessage (0);
		break;
	};
	return DefWindowProc(hWnd, message, wParam, lParam);
};

bool WindowInit (HINSTANCE hThisInst, int nCmdShow)
{
	WNDCLASSEX		    wcl;
	
	/* define the class of your main window */
  wcl.cbSize = sizeof(WNDCLASSEX);
	wcl.hInstance		= hThisInst;
	wcl.lpszClassName	= APPNAME;
	wcl.lpfnWndProc		= WindowProc;
	wcl.style			= 0;
	wcl.hIcon			= LoadIcon (hThisInst, IDC_ICON);
	wcl.hIconSm = LoadIcon (hThisInst, IDC_ICON);
	wcl.hCursor			= LoadCursor (hThisInst, IDC_ARROW);
	wcl.lpszMenuName	= NULL;
	wcl.cbClsExtra		= 0;
	wcl.cbWndExtra		= 0;
	wcl.hbrBackground	= (HBRUSH) GetStockObject (BLACK_BRUSH);

  /* Register class in Windows system */
	RegisterClassEx (&wcl);

  /* Create the window in memory */
	hWnd = CreateWindowEx( WS_EX_TOPMOST, APPNAME, APPTITLE, WS_OVERLAPPEDWINDOW, 75, 75, 320, 240, NULL, NULL, hThisInst, NULL);

	if(!hWnd) return false;
  
	return true;
};

bool AppInit (HINSTANCE hThisInst, int nCmdShow)
{
  if(!WindowInit (hThisInst, nCmdShow)) return false;

	ShowWindow (hWnd, nCmdShow);
	UpdateWindow (hWnd);

	return true;
};

int APIENTRY WinMain (HINSTANCE hThisInst, HINSTANCE hPrevInst, LPSTR lpCmdLine, int nCmdShow)
{
	MSG msg;
	if(!AppInit (hThisInst, nCmdShow)) return false;
	
	while (1)
	{
	  // Look if there are messages
		if(PeekMessage (&msg, NULL, 0, 0, PM_NOREMOVE))
		{
		  // Get the first message in the stack
			if(!GetMessage (&msg, NULL, 0, 0)) break;
			// Convert the message for WNDPROC functions
			TranslateMessage (&msg); 
			// Give the message to all applications
			DispatchMessage (&msg);
		}
		else
  	{
			// Do what you want when no message happens  
		}
	};

	return 0;
};

Hope I helped you.