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Win32 Button Commands


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#1 Captacha   Members   -  Reputation: 141

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Posted 10 August 2012 - 07:54 PM

In my code the WM_COMMAND segment causes my program to exit when I click on a button. Why is this? Shouldn't it do nothing?
LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wparam, LPARAM lparam)
{
switch(msg)
{
case WM_CREATE:
  CreateWindow("button", "Button 1", WS_VISIBLE | WS_CHILD, (width/2)-40, (height/2)-12, 80, 25, hwnd, (HMENU)1, NULL, NULL);
  CreateWindow("button", "Button 2", WS_VISIBLE | WS_CHILD, (width/2)-40, ((height/2)-12)-45, 80, 25, hwnd, (HMENU)2, NULL, NULL);
  break;
case WM_COMMAND:
  if(LOWORD(wparam) == 1)
  {
  }
case WM_CLOSE:
  DestroyWindow(hwnd);
  break;
case WM_DESTROY:
  PostQuitMessage(0);
  break;
default:
  return DefWindowProc(hwnd, msg, wparam, lparam);
  break;
}
}


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#2 ApochPiQ   Moderators   -  Reputation: 16079

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Posted 10 August 2012 - 08:52 PM

You seem to have left out a break; just above case WM_CLOSE.

#3 Endurion   Crossbones+   -  Reputation: 3654

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Posted 10 August 2012 - 10:29 PM

Not the problem here, but you don't return anything for any handled message. In most cases you also want to call DefWindowProc for handled messages.
Fruny: Ftagn! Ia! Ia! std::time_put_byname! Mglui naflftagn std::codecvt eY'ha-nthlei!,char,mbstate_t>

#4 dilyan_rusev   Members   -  Reputation: 1041

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Posted 11 August 2012 - 10:40 AM

And also you should return 0 for handled messages. I don't know if this is the full code, but I can't see a "return 0" statement. Returning 0 is important.

#5 Endurion   Crossbones+   -  Reputation: 3654

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Posted 11 August 2012 - 10:35 PM

And also you should return 0 for handled messages. I don't know if this is the full code, but I can't see a "return 0" statement. Returning 0 is important.

You cannot generally return 0. Look up the handled message and see what you should return (if you should do so).
Fruny: Ftagn! Ia! Ia! std::time_put_byname! Mglui naflftagn std::codecvt eY'ha-nthlei!,char,mbstate_t>

#6 SiCrane   Moderators   -  Reputation: 9629

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Posted 12 August 2012 - 12:23 AM

In particular, a common mistake is to return 0 from WM_NCCREATE, which indicates that window creation shouldn't proceed and causes CreateWindow()/CreateWindowEx() to return a NULL handle. Confusingly, WM_CREATE does the opposite: 0 indicates success.




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