HEXCALC程序可能是写程序偷懒的经典之作，如程序11-5所示。这个程序完全不呼叫CreateWindow，也不处理WM_PAINT消息，不取得设备内容，也不处理鼠标消息。但是它只用了不到150行的原始码，就构成了一个具有完整键盘和鼠标接口以及10种运算的十六进制计算器。计算器如图11-5所示。
程序11-5 HEXCALC
HEXCALC.C /*------------------------------------------------------------------------ HEXCALC.C -- Hexadecimal Calculator (c) Charles Petzold, 1998 -------------------------------------------------------------------------*/ #include <windows.h> LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM) ; int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance, PSTR szCmdLine, int iCmdShow) { static TCHAR szAppName[] = TEXT ("HexCalc") ; HWND hwnd ; MSG msg ; WNDCLASS wndclass ; wndclass.style = CS_HREDRAW | CS_VREDRAW; wndclass.lpfnWndProc = WndProc ; wndclass.cbClsExtra = 0 ; wndclass.cbWndExtra = DLGWINDOWEXTRA ; // Note! wndclass.hInstance = hInstance ; wndclass.hIcon = LoadIcon (hInstance, szAppName) ; wndclass.hCursor = LoadCursor (NULL, IDC_ARROW) ; wndclass.hbrBackground = (HBRUSH) (COLOR_BTNFACE + 1) ; wndclass.lpszMenuName = NULL ; wndclass.lpszClassName = szAppName ; if (!RegisterClass (&wndclass)) { MessageBox ( NULL, TEXT ("This program requires Windows NT!"), szAppName, MB_ICONERROR) ; return 0 ; } hwnd = CreateDialog (hInstance, szAppName, 0, NULL) ; ShowWindow (hwnd, iCmdShow) ; while (GetMessage (&msg, NULL, 0, 0)) { TranslateMessage (&msg) ; DispatchMessage (&msg) ; } return msg.wParam ; } void ShowNumber (HWND hwnd, UINT iNumber) { TCHAR szBuffer[20] ; wsprintf (szBuffer, TEXT ("%X"), iNumber) ; SetDlgItemText (hwnd, VK_ESCAPE, szBuffer) ; } DWORD CalcIt (UINT iFirstNum, int iOperation, UINT iNum) { switch (iOperation) { case '=': return iNum ; case '+': return iFirstNum + iNum ; case '-': return iFirstNum - iNum ; case '*': return iFirstNum * iNum ; case '&': return iFirstNum & iNum ; case '|': return iFirstNum | iNum ; case '^': return iFirstNum ^ iNum ; case '<': return iFirstNum << iNum ; case '>': return iFirstNum >> iNum ; case '/': return iNum iFirstNum / iNum: MAXDWORD ; case '%': return iNum iFirstNum % iNum: MAXDWORD ; default : return 0 ; } } LRESULT CALLBACK WndProc (HWND hwnd, UINT message, WPARAM wParam,LPARAM lParam) { static BOOL bNewNumber = TRUE ; static int iOperation = '=' ; static UINT iNumber, iFirstNum ; HWND hButton ; switch (message) { case WM_KEYDOWN: // left arrow --> backspace if (wParam != VK_LEFT) break ; wParam = VK_BACK ; // fall through case WM_CHAR: if ((wParam = (WPARAM) CharUpper ((TCHAR *) wParam)) == VK_RETURN) wParam = '=' ; if (hButton = GetDlgItem (hwnd, wParam)) { SendMessage (hButton, BM_SETSTATE, 1, 0) ; Sleep (100) ; SendMessage (hButton, BM_SETSTATE, 0, 0) ; } else { MessageBeep (0) ; break ; } // fall through case WM_COMMAND: SetFocus (hwnd) ; if (LOWORD (wParam) == VK_BACK) //backspace ShowNumber (hwnd, iNumber /= 16) ; else if (LOWORD (wParam) == VK_ESCAPE) // escape ShowNumber (hwnd, iNumber = 0) ; else if (isxdigit (LOWORD (wParam))) // hex digit { if (bNewNumber) { iFirstNum = iNumber ; iNumber = 0 ; } bNewNumber = FALSE ; if (iNumber <= MAXDWORD >> 4) ShowNumber (hwnd, iNumber = 16 * iNumber + wParam - (isdigit (wParam) '0': 'A' - 10)) ; else MessageBeep (0) ; } else // operation { if (!bNewNumber) ShowNumber (hwnd, iNumber = CalcIt (iFirstNum, iOperation, iNumber)) ; bNewNumber = TRUE ; iOperation = LOWORD (wParam) ; } return 0 ; case WM_DESTROY: PostQuitMessage (0) ; return 0 ; } return DefWindowProc (hwnd, message, wParam, lParam) ; }