C / C++ / MFC

#include <windows.h> // windows.h
#include <math.h>    // math.h
#include <process.h> // process.h

typedef struct
{
	HWND hwnd;
	int cxClient;
	int cyClient;
	int cyChar;
	BOOL bKill;
}
PARAMS, *PPARAMS;

LRESULT APIENTRY WndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam); 

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, 
						 PSTR szCmdLine, int iCmdShow)
{
	static TCHAR szAppName[] = TEXT("Multi2");
	HWND hwnd;
	MSG msg;
	WNDCLASS wc;

	wc.style				= CS_HREDRAW | CS_VREDRAW;
	wc.lpfnWndProc		= WndProc;
	wc.cbClsExtra		= 0;
	wc.cbWndExtra		= 0;
	wc.hInstance		= hInstance;
	wc.hIcon				= LoadIcon(NULL, IDI_APPLICATION);
	wc.hCursor			= LoadCursor(NULL, IDC_ARROW);
	wc.hbrBackground	= (HBRUSH) GetStockObject(WHITE_BRUSH);
	wc.lpszMenuName	= NULL;
	wc.lpszClassName	= szAppName;

	if (!RegisterClass(&wc))
	{
		MessageBox(NULL, TEXT("This Program Requires Windows NT!"),
					  szAppName, MB_ICONERROR);
		return 0;
	}

	hwnd = CreateWindow(szAppName, TEXT("Multitasking Demo using Threads"),
							  WS_OVERLAPPEDWINDOW,
							  CW_USEDEFAULT, CW_USEDEFAULT,
							  CW_USEDEFAULT, CW_USEDEFAULT,
							  NULL, NULL, hInstance, NULL);

	ShowWindow(hwnd, iCmdShow);
	UpdateWindow(hwnd);

	while (GetMessage(&msg, NULL, 0, 0))
	{
		TranslateMessage(&msg);
		DispatchMessage(&msg);
	}
	return msg.wParam;
}

int CheckBottom(HWND hwnd, int cyClient, int cyChar, int iLine)
{
	if (iLine * cyChar + cyChar > cyClient)
	{
		InvalidateRect(hwnd, NULL, TRUE);
		UpdateWindow(hwnd);
		iLine = 0;
	}
	return iLine;
}

/*----------------------------------------------------
    Window 2: Display increasing sequence of numbers
  ----------------------------------------------------*/
void Thread1(PVOID pvoid)
{
	HDC hdc;
	int iNum = 0, iLine = 0;
	PPARAMS pparams;
	TCHAR szBuffer[16];

	pparams = (PPARAMS) pvoid;

	while (!pparams->bKill)
	{
		if (iNum < 0)
			iNum = 0;

		iLine = CheckBottom(pparams->hwnd, pparams->cyClient, 
								  pparams->cyChar, iLine);

		hdc = GetDC(pparams->hwnd);

		TextOut(hdc, 0, iLine * pparams->cyChar, szBuffer,
				  wsprintf(szBuffer, TEXT("%d"), iNum++));

		ReleaseDC(pparams->hwnd, hdc);
		iLine++;
	}
	_endthread();
}

LRESULT APIENTRY WndProc1(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
	static PARAMS params;

	switch (message)
	{
		case WM_CREATE:
			params.hwnd = hwnd;
			params.cyChar = HIWORD(GetDialogBaseUnits());
			_beginthread(Thread1, 0, ¶ms);	
			return 0;

		case WM_SIZE:
			params.cyClient = HIWORD(lParam);
			return 0;

		case WM_DESTROY:
			params.bKill = TRUE;
			return 0;
	}
	return DefWindowProc(hwnd, message, wParam, lParam);
}

/*---------------------------------------------------------
    Window 2: Display incresing sequence of prime numbers
  ---------------------------------------------------------*/
void Thread2(PVOID pvoid)
{
	HDC hdc;
	int iNum = 1, iLine = 0, i, iSqrt;
	PPARAMS pparams;
	TCHAR szBuffer[16];

	pparams = (PPARAMS) pvoid;

	while (!pparams->bKill)
	{
		do
		{
			if (++iNum < 0)
				iNum = 0;

			iSqrt = (int) sqrt(iNum);
			for (i = 2; i <= iSqrt; i++)
				if (iNum % i == 0)
					break;
			}
			while (i <= iSqrt);

		iLine = CheckBottom(pparams->hwnd, pparams->cyClient,
								  pparams->cyChar, iLine);

		hdc = GetDC(pparams->hwnd);

		TextOut(hdc, 0, iLine * pparams->cyChar, szBuffer,
				  wsprintf(szBuffer, TEXT("%d"), iNum));

		ReleaseDC(pparams->hwnd, hdc);
		iLine++;
	}
	_endthread();
}

LRESULT APIENTRY WndProc2(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
	static PARAMS params;

	switch (message)
	{
		case WM_CREATE:
			params.hwnd = hwnd;
			params.cyChar = HIWORD(GetDialogBaseUnits());
			_beginthread(Thread2, 0, ¶ms);
			return 0;

		case WM_SIZE:
			params.cyClient = HIWORD(lParam);
			return 0;

		case WM_DESTROY:
			params.bKill = TRUE;
			return 0;
	}
	return DefWindowProc(hwnd, message, wParam, lParam);
}

/*--------------------------------------------------------------
	 Window 3: Display incresing sequences of Fibonacci numbers
  --------------------------------------------------------------*/
void Thread3(PVOID pvoid)
{
	HDC hdc;
	int iNum = 0, iNext = 1, iLine = 0, iTemp;
	PPARAMS pparams;
	TCHAR szBuffer[16];

	pparams = (PPARAMS) pvoid;

	while (!pparams->bKill)
	{
		if (iNum < 0)
		{
			iNum = 0;
			iNext = 1;
		}
		iLine = CheckBottom(pparams->hwnd, pparams->cyClient,
								  pparams->cyChar, iLine);

		hdc = GetDC(pparams->hwnd);

		TextOut(hdc, 0, iLine * pparams->cyChar, szBuffer,
				  wsprintf(szBuffer, TEXT("%d"), iNum));

		ReleaseDC(pparams->hwnd, hdc);
		iTemp = iNum;
		iNum = iNext;
		iNext += iTemp;
		iLine++;
	}
	_endthread();
}

LRESULT APIENTRY WndProc3(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
	static PARAMS params;

	switch (message)
	{
		case WM_CREATE:
			params.hwnd = hwnd;
			params.cyChar = HIWORD(GetDialogBaseUnits());
			_beginthread(Thread3, 0, ¶ms);
			return 0;		

		case WM_SIZE:
			params.cyClient = HIWORD(lParam);
			return 0;

		case WM_DESTROY:
			params.bKill = TRUE;
			return 0;
	}
	return DefWindowProc(hwnd, message, wParam, lParam);
}

/*---------------------------------------------
	 Window 4: Display circles of random radii
  ---------------------------------------------*/
void Thread4(PVOID pvoid)
{
	HDC hdc;
	int iDiameter;
	PPARAMS pparams;

	pparams = (PPARAMS) pvoid;

	while (!pparams->bKill)
	{
		InvalidateRect(pparams->hwnd, NULL, TRUE);
		UpdateWindow(pparams->hwnd);

		iDiameter = rand() % (max (1, 
										min(pparams->cxClient, pparams->cyClient)));

		hdc = GetDC(pparams->hwnd);

		Ellipse(hdc, (pparams->cxClient - iDiameter) / 2,
						 (pparams->cyClient - iDiameter) / 2,
						 (pparams->cxClient + iDiameter) / 2,
						 (pparams->cyClient + iDiameter) / 2);

		ReleaseDC(pparams->hwnd, hdc);
	}
	_endthread();
}

LRESULT APIENTRY WndProc4(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
	static PARAMS params;

	switch (message)
	{
		case WM_CREATE:
			params.hwnd = hwnd;
			params.cyChar = HIWORD(GetDialogBaseUnits());
			_beginthread(Thread4, 0, ¶ms);
			return 0;	

		case WM_SIZE:
			params.cxClient = LOWORD(lParam);
			params.cyClient = HIWORD(lParam);
			return 0;

		case WM_DESTROY:
			params.bKill = TRUE;
			return 0;
	}
	return DefWindowProc(hwnd, message, wParam, lParam);
}

/*---------------------------------------
	 Main window to create child windows
  ---------------------------------------*/
LRESULT APIENTRY WndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
	static HWND hwndChild[4];
	static TCHAR* szChildClass[] = { TEXT("Child1"), TEXT("Child2"),
												TEXT("Child3"), TEXT("Child4") };
	static WNDPROC ChildProc[] = { WndProc1, WndProc2, WndProc3, WndProc4 };
	HINSTANCE hInstance;
	int i, cxClient, cyClient;
	WNDCLASS wc;

	switch (message)
	{
		case WM_CREATE:
			hInstance = (HINSTANCE) GetWindowLong(hwnd, GWL_HINSTANCE);

			wc.style				= CS_HREDRAW | CS_VREDRAW;
			wc.cbClsExtra		= 0;
			wc.cbWndExtra		= 0;
			wc.hInstance		= hInstance;
			wc.hIcon				= NULL;
			wc.hCursor			= LoadCursor(NULL, IDC_ARROW);
			wc.hbrBackground	= (HBRUSH) GetStockObject(WHITE_BRUSH);
			wc.lpszMenuName	= NULL;

			for (i = 0; i < 4; i++)
			{
				wc.lpfnWndProc	= ChildProc[i];
				wc.lpszClassName = szChildClass[i];

				RegisterClass(&wc);

				hwndChild[i] = CreateWindow(szChildClass[i], NULL, 
													 WS_CHILDWINDOW | WS_BORDER | WS_VISIBLE,
													 0, 0, 0, 0,
													 hwnd, (HMENU) i, hInstance, NULL);
			}
			return 0;

		case WM_SIZE:
			cxClient = LOWORD(lParam);
			cyClient = HIWORD(lParam);

			for (i = 0; i < 4; i++)
				MoveWindow(hwndChild[i], (i % 2) * cxClient / 2,
												 (i > 1) * cyClient / 2,
							  cxClient / 2, cyClient / 2, TRUE);
			return 0;

		case WM_CHAR:
			if (wParam == '\x1B')
				DestroyWindow(hwnd);
			return 0;

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