Re: Windows App - C++

From: August1 (anthonyb_nc_at_hotmail.com)
Date: 10/20/04 

Date: 20 Oct 2004 01:18:31 -0700

> Because you forgot to compile and run the program?
>
> If you have any problems with compiling, ask in a compiler-specific
> newsgroup.
>
> If you have any problems getting the program to run, ask in a Windows-specific
> newsgroup.
>
>
>
> > #include <windows.h>
>
> For C++ always #define STRICT and NOMINMAX before this #include.
>
>
> > #include <string.h>
>
> Preferentially use
>
>
> #include <cstring>
>
>
>
> > long WINAPI MainWndProc(HWND,UINT,WPARAM,LPARAM);
> >
> > HWND hWnd;
>
> Don't use global variables.
>
>
> > HWND hwndEdit;
> > HWND hwndButton;
> > HWND hwndClearButton;
> > char szMessage[50] = "";
>
> Here you're into buffer overflow territory; instead consider
> std::string.
>
>
>
> > int WINAPI WinMain(HINSTANCE hInstance,
> > HINSTANCE hPrevInstance,
> > LPSTR lpCmdLine,
> > int nCmdShow)
> > {
>
> Check out your compiler's support for standard 'main'. g++ supports
> that directly for Windows GUI application. Use standard 'main'.
>
>
> > WNDCLASS wc;
> > wc.lpszClassName = "Style1";
> > wc.lpfnWndProc = MainWndProc;
> > wc.style = CS_OWNDC | CS_VREDRAW | CS_HREDRAW;
> > wc.hInstance = hInstance;
> > wc.hIcon = LoadIcon(NULL,IDI_APPLICATION);
> > wc.hCursor = LoadCursor(NULL,IDC_ARROW);
> > wc.hbrBackground = (HBRUSH)( COLOR_WINDOW+1 );
> > wc.lpszMenuName = "";
> > wc.cbClsExtra = 0;
> > wc.cbWndExtra = 0;
> > RegisterClass(&wc);
>
> A simpler way might be to use an initializer, "WNDCLASS wc = { ... };".
>
> Anyway, to ensure all non-assigned fields are zero, declare it like
>
>
> WNDCLASS wc = {0};
>
>
>
>
> > hWnd = CreateWindow("Style1","Border Demonstration",
> > WS_OVERLAPPEDWINDOW,CW_USEDEFAULT,CW_USEDEFAULT,
> > 185,265,NULL,NULL,hInstance,NULL);
> >
> > hwndEdit = CreateWindow("EDIT",NULL,
> > WS_VISIBLE | WS_CHILD | WS_BORDER | ES_LEFT,
> > 10,10,155,20,hWnd,NULL,hInstance,NULL);
> >
> > hwndButton = CreateWindow("BUTTON","Message",
> > WS_VISIBLE | WS_CHILD | BS_DEFPUSHBUTTON,
> > 10,40,35,35,hWnd,NULL,hInstance,NULL);
> >
> > hwndClearButton = CreateWindow("BUTTON","Clear",
> > WS_VISIBLE | WS_CHILD | BS_DEFPUSHBUTTON,
> > 50,40,35,35,hWnd,NULL,hInstance,NULL);
>
> Error checking might be a good idea... For example using a function
>
> template< typename T >
> inline void throwIf0( T const& x )
> {
> if( !x ) { throw std::runtime_error( "Ooops." ); }
> }
>
> Then
>
> hWnd = CreateWindow("Style1","Border Demonstration",
> WS_OVERLAPPEDWINDOW,CW_USEDEFAULT,CW_USEDEFAULT,
> 185,265,NULL,NULL,hInstance,NULL);
> throwIf0( hWnd );
>
> of course with a 'catch' somewhere.
>
>
> > ShowWindow(hWnd,nCmdShow);
> >
> > MSG msg;
> > while(GetMessage(&msg,NULL,0,0))
> > {
> > TranslateMessage(&msg);
> > DispatchMessage(&msg);
> > }
> > return msg.wParam;
>
> Here should be cast to the return type, i.e.
>
>
> return static_cast<int>( msg.wParam );
>
>
> > }//end WinMain()
>
>
>
>
> > long WINAPI MainWndProc(HWND hWnd,UINT msg,WPARAM wParam,LPARAM
> > lParam)
> > {
> > HWND hwndCtl = (HWND)lParam;
>
> Don't use C style casts.
>
> In this case, use a reinterpret_cast or the appropriate system-specific
> macro/function (off-topic hint: <windowsx.h>).
>
> Anyway the logic is flawed: you don't yet have enough information to
> say that this argument represents what you think it does. But it works.
> With a bit of maintainance it will cease to work.
>
>
> > switch(msg)
> > {
> > case WM_COMMAND:
> > switch(wParam)
> > {
> > case BN_CLICKED:
> > if(hwndCtl == hwndButton)
> > {
> > strcpy(szMessage,"This program is an overlapped style Window.");
>
> Buffer overflow?
>
> Indentation!
>
>
> > SetWindowText(hwndEdit,szMessage);
> > }
> > else if(hwndCtl == hwndClearButton)
> > {
> > strcpy(szMessage,"");
> > SetWindowText(hwndEdit,szMessage);
> > }
> > }
> > break;
> > case WM_DESTROY:
> > PostQuitMessage(0);
> > return 0;
> > default:
> > return DefWindowProc(hWnd,msg,wParam,lParam);
> > }
> >
> > return 0;
>
> Unreachable.
>
> > }//end MainWndProc()

hello alf,

   thank you for your substantive and even-tempered contribution. the
problem appears to have been resolved prior to any replies. i am also
reviewing the specific suggestions you've presented (code-related) for
subsequent use. very relevant.

regards

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