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Compiling windows apps (not using MFC) with .cpp extension

I am using Microsoft VC++ 5.0

I've been writing a windows app in C, recently I changed the file extension of the main project file to .cpp so I could use some handy classes I created a while ago. Everything was fine after the change except that the DialogBoxParam func will not compile (this worked fine before), the actual code in question is below along with the error.

DialogBoxParam(hInstance, MAKEINTRESOURCE(IDD_TRANSACTION), hwnd, TransactionDialogProc, NULL);

error C2664: 'DialogBoxParamA' : cannot convert parameter 4 from 'int (void *,unsigned int,unsigned int,long)' to 'int (__stdcall *)(void)'

will this conversion not work in c++? I can't imagine that I can't use a dialog box just because I am using the cpp complier

ASKER CERTIFIED SOLUTION

chensu

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chensu

And you may need to type cast as follows.

DialogBoxParam(hInstance, MAKEINTRESOURCE(IDD_TRANSACTION), hwnd, (DLGPROC)TransactionDialogProc, NULL);

NickRepin

Nice shot :)

Try

Right on, "chensu", ... right on!!

Try

"camejos" do you understand what "chensu" has done? If you don't, this is your moment to ask questions.

nils pipenbrinck

Funny..

I had the same problem yesterday night writing an example code for the c++ programming area :)

I've simply casted the function pointer to DLGPROC and it compiled...

nils

nils pipenbrinck

the code line was:

DialogBox (hInstance, "DIALOG_1", 0, DlgFunc);

the c++ version is:

DialogBox (hInstance, "DIALOG_1", 0, (DLGPROC) DlgFunc);

chensu

If you are used to C programming, you will experience a lot of such things in C++ due to C++'s strong type check. The new C++ standard also introduces four type cast operators - static_cast, const_cast, reinterpret_cast and dynamic_cast.

Try

Some of these cast operators are equivalent to playing with fire, which we know can cause severe discomfort. For example, 'const_cast' allows 'const-ness' to be cast away.

C++ then goes one step further and in addition to 'const_cast', provides the storage class specifier 'mutable' as an alternative to 'const_cast'. A 'mutable' data member is ALWAYS modifiable even in a 'const' member function or 'const' object.

Handle with care, or keep a lot of heartburn remedies nearby.

nils pipenbrinck

<offtopic, sorry>

I'm very glad about these new typecasting things..

you know.. when I really want to modify a const value I can do it.. using inline assembler or void * casting... the whole thing just makes it more portable.

</offtopic, sorry>

nils