GetWindowLong Problem.

[Gator F]

I'm writing a wrapper around the Win32 API. I have a class for editing a window, this class has methods for getting/setting the location, text, window styles, ect. This is what I have for the GetStyles method:

DWORD WindowEditing::GetStyles (int iFlags)
{
    return GetWindowLong (hHandle, iFlags);
}

When I try to use the function, it doesn't return the correct value, example, I'll use this:

WindowEditing Edit (hWnd);
if (Edit.GetStyles (GWL_STYLE) == WS_OVERLAPPEDWINDOW) MessageBox (0,0,0,0);

And a blank message box will not show up.

Can anyone help? Thanks.

[gpotw]

You should change the == to a &. You want to test if the bits(WS_OVERLAPPEDWINDOW) are set, not for the actual value of WS_OVERLAPPEDWINDOW.

[Disch]

In addition to that, WS_OVERLAPPEDWINDOW is in fact a combination of flags. So if you only do & if will give you a false positive if any of those flags are set.

For example:

int style = WS_SYSMENU;

if(style & WS_OVERLAPPEDWINDOW)
{
  // this block will execute, because WS_SYSMENU is part of WS_OVERLAPPEDWINDOW
  //  and therefore the & returns nonzero
}

To check for the whole WS_OVERLAPPEDWINDOW style, you need to make sure that all the WS_OVERLAPPEDWINDOW flags are set. You do this with a combination of & and ==:

if( (style & WS_OVERLAPPEDWINDOW) == WS_OVERLAPPEDWINDOW )

[Gator F]

Thanks guys.