SetWindowLong 和SetClassLong区别

首先看一下msdn是怎样定义它们的吧，可不要搞错啊：

The SetWindowLong function changes an attribute of the specified window. The function also sets the 32-bit (long) value at the specified offset into the extra window memory.

Note  This function has been superseded by the SetWindowLongPtr function. To write code that is compatible with both 32-bit and 64-bit versions of Microsoft Windows, use the SetWindowLongPtr function.

Syntax

LONG SetWindowLong(      

    HWND hWnd,
    int nIndex,
    LONG dwNewLong
);

上面是对SetWindowLong的说明（定义），注意红色字体。

下面是SetClassLong的说明：

The SetClassLong function replaces the specified 32-bit (long) value at the specified offset into the extra class memory or the WNDCLASSEX structure for the class to which the specified window belongs.

Note  This function has been superseded by the SetClassLongPtr function. To write code that is compatible with both 32-bit and 64-bit versions of Microsoft Windows, use SetClassLongPtr.

Syntax

DWORD SetClassLong(      

    HWND hWnd,
    int nIndex,
    LONG dwNewLong
);

注意红色字体表示。

这里要注意