SetClassWord function (winuser.h)

Replaces the 16-bit (WORD) value at the specified offset into the extra class memory for the window class to which the specified window belongs.

Note  This function is provided only for compatibility with 16-bit versions of Windows. Applications should use the SetClassLong function.


WORD SetClassWord(
  [in] HWND hWnd,
  [in] int  nIndex,
  [in] WORD wNewWord


[in] hWnd

Type: HWND

A handle to the window and, indirectly, the class to which the window belongs.

[in] nIndex

Type: int

The zero-based byte offset of the value to be replaced. Valid values are in the range zero through the number of bytes of class memory minus two; for example, if you specified 10 or more bytes of extra class memory, a value of 8 would be an index to the fifth 16-bit integer.

[in] wNewWord

Type: WORD

The replacement value.

Return value

Type: WORD

If the function succeeds, the return value is the previous value of the specified 16-bit integer. If the value was not previously set, the return value is zero.

If the function fails, the return value is zero. To get extended error information, call GetLastError.


Reserve extra class memory by specifying a nonzero value in the cbClsExtra member of the WNDCLASS structure used with the RegisterClass function.


Requirement Value
Minimum supported client Windows 2000 Professional [desktop apps only]
Minimum supported server Windows 2000 Server [desktop apps only]
Target Platform Windows
Header winuser.h (include Windows.h)
Library User32.lib
DLL User32.dll

See also







Window Classes