Thread: Messageboxes will work in win2k, fail in XP

As a sort of introductory app to windows applications in C++, I've written a short program that displays a few messageboxes, and plays around with the buttons in them (OK, OKCANCEL, etc).

It works beautifully in Windows 2000. However, it silently fails (i.e. no error messages) in XP and I'm not sure why that is. I use both OSes, so I want to be able to run the app in both of them.

Here's the important part of the code: (I've removed a few things from the code, but trust me I didn't omit anything pertinent)

Code:

//sorry for the immature variable/window naming :P
#include <windows.h>

int WINAPI
WinMain(HINSTANCE hInst, 
	HINSTANCE hPrevInstance,
	LPSTR lpCmdLine,
        int nCmdShow)
{
    int lol = MessageBox (NULL, "This is a message box", 
                "OMG", MB_OKCANCEL);
    if (lol == 2) //if user clicked cancel
        return 0;
    MessageBox (NULL, "Why did you select cancel?", 
                "ERROR", 0 + 48);
    return 0;
}

Is there something in that code that's win2k specific? Is it to do with the OS it was compiled on? Ideally I'd like some code that runs the same on both OSes, but if I have to, I'll settle with compiling a seperate version for each.

Any help is appreciated!

-Rippy

Really stupid question, but did you build in release mode?

Actually, I had a comment on that very line like this:

Code:

MessageBox (NULL, "Why did you select cancel?", 
                "ERROR", 0 + 48); //0 makes it an OK message, 48 adds the exclamation mark icon

Seeing as I'm new to this, I've been kind of inconsistent (my very first test messagebox used MB_OK instead of 0). But I see how using the appropriate names is a bit more effective than adding a comment.

As for the "lol == 2" thing, I'll admit that that was a complete shot in the dark. I just knew that Messagebox returned a value, so I tried a few values to see which corresponded to each button.

I don't have access to my code at the moment, but hopefully that's the problem. I'll also check to see if I'm building it properly as the first poster asked, because I don't remember explicitly setting anything.

Thanks for all the replies =D

Originally Posted by Rippy

Actually, I had a comment on that very line like this:

Code:

MessageBox (NULL, "Why did you select cancel?", 
                "ERROR", 0 + 48); //0 makes it an OK message, 48 adds the exclamation mark icon

Clarity to the programmer is part of it. Clarity to the compiler is the other.

The macro might change values with different OSes for example.

So use the macro, constant, or whatever, not the literal.

The Win32 docs will show you specifically what values MessageBox() will take. Some samples are:

Buttons
MB_YESNO
MB_OK (default)
MB_OKCANCEL

Message Types
MB_ICONEXCLAMATION
MB_ICONINFORMATION
MB_ICONWARNING
MB_ICONQUESTION

Return values
ID_OK
ID_YES
ID_NO
ID_CANCEL


You can achieve the desired buttons with the desired type by ORing these constants.

Ok, well, my googling for a release build in Dev-C++ gave me next to no results. What do you mean by that?

I've applied the other suggestions already, though unfortunately I again don't have access to my XP machine (backup restore gone wrong, heh). Thanks though, the code is definitely more clear now.

My guess is that your winXP machine is missing a required .DLL to run the application, but then again i don't understand gcc as well as VS.

It works! I think it was somehow to do with using those macros. Thanks for the help