Win API doesn't working

[WhiteHat]

Hi everybody,
I have problem with Win API programming in Code::Blocks. I typed really easy Win API source code, Code::Blocks compiled it and made an .exe file. But this file can't be execute. Can You help me pls?

Code, I've typed:

Code

#include <windows.h>
int WINAPI WinMain(HINSTANCE hInstance,HINSTANCE hPrevInstance,
                                PSTR szCmdLine, int iCmdShow)
{
     MessageBox(NULL, TEXT("Ahoj světe"), TEXT("Programujeme"),0);
     return 0;
}

[Michael]

Hello,

Which C::B revision? Compiler? Not MinGW, because it does not compile you code .

Which errors did you get?

Best wishes,
Michael

[MortenMacFly]

I have problem with Win API programming in Code::Blocks.

A few more details would be nice:
- What C::B version are you using?
- What compiler are you using?
- What was your template? (A Windows GUI application, a console application, a file-only)?
- (In case of MSVCTK): do you link against gdi32.lib user32.lib kernel32.lib?
- (In case of GCC): do you link against gdi32 user32 kernel32 windows?
With regards, Morten.
BTW: If you remove your message box it compiles/runs fine for me (with MSVCTK and GCC).
Edit: Ooops, Michael was a few seconds faster than I - but we share the same questions... ;-)

[Michael]

Edit: Ooops, Michael was a few seconds faster than I - but we share the same questions... ;-)

But your questions are much more precise and detailed .

Best wishes,
Michael

[WhiteHat]

Well guys, thanks a lot, but I think, I have resolved this problem, as You've said, problem is with compiler (Mingw) Now I had dowbloaded Win32 compiler and everything is OK, only: I have to set build option in every project, how could I set it automaticly?

[Michael]

Well guys, thanks a lot, but I think, I have resolved this problem, as You've said, problem is with compiler (Mingw) Now I had dowbloaded Win32 compiler and everything is OK, only: I have to set build option in every project, how could I set it automaticly?

You did build an .exe with MinGW :?? Strange, because MinGW seems not to support WinMain AFAIK (but I may be wrong).

Compiler Options could be set globally for every projects under:

Settings-->Compiler and debugger-->Global compiler settings.

Or locally (for the whole project or for every target) under:

Project-->Build options

Best wishes,
Michael

[TDragon]

Strange, because MinGW seems not to support WinMain AFAIK (but I may be wrong).

Unless I've completely misunderstood you, you are wrong.

The code as posted fails to compile for me, because my default encoding doesn't support the non-ASCII characters; however, if I replace them with something harmless everything compiles and executes cleanly.

WhiteHat: Does it work when debugging from Code::Blocks (hit F8)? What exactly happens or doesn't happen when you try to run the executable?

[sethjackson]

MinGW supports WinMain for sure.  Umm why would you think otherwise :?

[WhiteHat]

Compiler is fine. No error message while compiling, but .exe file can't be runed. I don't know what type of project have I choose.

If I try to run .exe file, there will be console window for a while and nothing happens.

[David Perfors]

looks like you have choosen a console application. Go to the Project settings and change the application type to GUI application.

[Michael]

Strange, because MinGW seems not to support WinMain AFAIK (but I may be wrong).

Unless I've completely misunderstood you, you are wrong.

Hmmm. When compiling I got the same problem as here:

http://forums.codeblocks.org/index.php?topic=3374.0

May be I have forgotten to add a library or two.

Best wishes,
Michael

[Vampyre_Dark]

MinGW always supported WinMain for me. You just add -mwindows or something.  :| :?

[thomas]

The reason it fails is that you use illegal byte sequences ("Ahoj světe") which somehow screws up the compiler.

If you save the document as UTF-8, it compiles just fine. As an alternative, you could tell gcc to use a different encoding.

[sethjackson]

MinGW always supported WinMain for me. You just add -mwindows or something.  :| :?

Uhh I never had to do that either.....  :? Look in the C::B Win32 GUI template. You need to link gdi32, user32, and kernel32. There is no -mwindows to be found. Of course you have to include <windows.h>, and for MinGW you must download the winapi package for things to work.

@Michael

Umm that topic was talking about wmain not WinMain. The entry point for GUI (console apps don't count) apps on Windows is WinMain.

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/winui/winui/windowsuserinterface/windowing/windows/windowreference/windowfunctions/winmain.asp

[thomas]

The only real problem with this code snippet is that it is not properly encoded.

If you paste it into an empty document and save with "default encoding" (which is Windows-something) then it fails to compile on my  machine, too. However, if you save the exact same file with UTF-8 encoding, all is fine.

This makes sense, too, since gcc uses UTF-8 as default encoding (unless told otherwise), and ět in Windows-something is not valid in UTF-8.
The only thing that is not quite right about it is that gcc does not report this as "illegal sequence" but simply fails silently, outputting an emtpy object file (which of course misses the WinMain function, as the linker correctly complains about).

Regarding main/WinMain, much to everybody's surprise MinGW is smart enough to wrap up everything so it still works, even if you use main instead of WinMain for a Windows application. The only obvious disadvantage is that you don't have easy access to hInstance and hPrevInstance, but they can be queried if needed (and who needs them anyway).

[kkez]

(and who needs them anyway).

Well, the latter is useless, but you need the first one to create a window but you're right, you can get it easily.

[sethjackson]

(and who needs them anyway).

Well, the latter is useless, but you need the first one to create a window but you're right, you can get them easily.

Actually you don't.

Consider this (it works).

This is a slightly modified version of the Win32 GUI template provided with C::B.

The only things that are changed is the entry point (main not WinMain),  GetModuleHandle(0) instead of hThisInstance, ShowWindow uses SW_SHOW instead of nCmdShow.

Code: cpp

#include <windows.h>

/*  Declare Windows procedure  */
LRESULT CALLBACK WindowProcedure (HWND, UINT, WPARAM, LPARAM);

/*  Make the class name into a global variable  */
char szClassName[ ] = "CodeBlocksWindowsApp";

int main(int argc, char* argv[])
{
    HWND hwnd;               /* This is the handle for our window */
    MSG messages;            /* Here messages to the application are saved */
    WNDCLASSEX wincl;        /* Data structure for the windowclass */

    /* The Window structure */
    wincl.hInstance = GetModuleHandle(0);
    wincl.lpszClassName = szClassName;
    wincl.lpfnWndProc = WindowProcedure;      /* This function is called by windows */
    wincl.style = CS_DBLCLKS;                 /* Catch double-clicks */
    wincl.cbSize = sizeof (WNDCLASSEX);

    /* Use default icon and mouse-pointer */
    wincl.hIcon = LoadIcon (NULL, IDI_APPLICATION);
    wincl.hIconSm = LoadIcon (NULL, IDI_APPLICATION);
    wincl.hCursor = LoadCursor (NULL, IDC_ARROW);
    wincl.lpszMenuName = NULL;                 /* No menu */
    wincl.cbClsExtra = 0;                      /* No extra bytes after the window class */
    wincl.cbWndExtra = 0;                      /* structure or the window instance */
    /* Use Windows's default colour as the background of the window */
    wincl.hbrBackground = (HBRUSH) COLOR_BACKGROUND;

    /* Register the window class, and if it fails quit the program */
    if (!RegisterClassEx (&wincl))
        return 0;

    /* The class is registered, let's create the program*/
    hwnd = CreateWindowEx (
           0,                   /* Extended possibilites for variation */
           szClassName,         /* Classname */
           "Code::Blocks Template Windows App",       /* Title Text */
           WS_OVERLAPPEDWINDOW, /* default window */
           CW_USEDEFAULT,       /* Windows decides the position */
           CW_USEDEFAULT,       /* where the window ends up on the screen */
           544,                 /* The programs width */
           375,                 /* and height in pixels */
           HWND_DESKTOP,        /* The window is a child-window to desktop */
           NULL,                /* No menu */
           GetModuleHandle(0),       /* Program Instance handler */
           NULL                 /* No Window Creation data */
           );

    /* Make the window visible on the screen */
    ShowWindow (hwnd, SW_SHOW);

    /* Run the message loop. It will run until GetMessage() returns 0 */
    while (GetMessage (&messages, NULL, 0, 0))
    {
        /* Translate virtual-key messages into character messages */
        TranslateMessage(&messages);
        /* Send message to WindowProcedure */
        DispatchMessage(&messages);
    }

    /* The program return-value is 0 - The value that PostQuitMessage() gave */
    return messages.wParam;
}


/*  This function is called by the Windows function DispatchMessage()  */

LRESULT CALLBACK WindowProcedure (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    switch (message)                  /* handle the messages */
    {
        case WM_DESTROY:
            PostQuitMessage (0);       /* send a WM_QUIT to the message queue */
            break;
        default:                      /* for messages that we don't deal with */
            return DefWindowProc (hwnd, message, wParam, lParam);
    }

    return 0;
}

[TDragon]

The only thing that is not quite right about it is that gcc does not report this as "illegal sequence" but simply fails silently, outputting an emtpy object file (which of course misses the WinMain function, as the linker correctly complains about).

Correct me if I'm wrong, but I thought this was because the invalid characters caused C::B to save an empty source file (rather than the fault belonging to GCC)?

[thomas]

You're right. I was convinced it only showed an empty file if the encoding was not good, but it really saves an empty file!

[Michael]

@Michael

Umm that topic was talking about wmain not WinMain. The entry point for GUI (console apps don't count) apps on Windows is WinMain.

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/winui/winui/windowsuserinterface/windowing/windows/windowreference/windowfunctions/winmain.asp

Yes, I know about WinMain (at least that it exists and what is it ), but I got the same WinMain error, by using wmain, WinMain and other that I have forgotten. I will look at this stuff a bit later when I will have some free time.

Best wishes,
Michael

[kkez]

(and who needs them anyway).

Well, the latter is useless, but you need the first one to create a window but you're right, you can get them easily.

Actually you don't.

You need the instance, in one way (using the WinMain argument) or another (using GetModuleHandle(NULL)). But you need it
The cmdShow can't be replaced the same way, since if you ShellExecute/CreateProcess one program and require it to start hidden or maximized or whatever, with that code you always show it...

[sethjackson]

(and who needs them anyway).

Well, the latter is useless, but you need the first one to create a window but you're right, you can get them easily.

Actually you don't.

You need the instance, in one way (using the WinMain argument) or another (using GetModuleHandle(NULL)). But you need it
The cmdShow can't be replaced the same way, since if you ShellExecute/CreateProcess one program and require it to start hidden or maximized or whatever, with that code you always show it...

Well can't you just do ShowWindow(wnd, SW_HIDE)..... :?  I read your post wrong. Sorry.  :oops: You need the instance, but how you go about getting it is another matter.

[kkez]

Well can't you just do ShowWindow(wnd, SW_HIDE)..... :?

Well, how do you know if it should be hidden or maximized or normal without the cmdShow that is passed to WinMain from ShellExecute or CreateProcess?

[sethjackson]

Well can't you just do ShowWindow(wnd, SW_HIDE)..... :?

Well, how do you know if it should be hidden or maximized or normal without the cmdShow that is passed to WinMain from ShellExecute or CreateProcess?

Hmm good question..... Maybe GetStartupInfo()?

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dllproc/base/getstartupinfo.asp
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dllproc/base/startupinfo_str.asp

[kkez]

You're right i didn't know that function.