GetWindowLong (Compact 2013)

3/28/2014

This function retrieves information about the specified window. GetWindowLong also retrieves the 32-bit (long) value at the specified offset into the extra window memory of a window.

Syntax

LONG GetWindowLong( 
  HWND hWnd, 
  int nIndex
); 

Parameters

• hWnd
  Handle to the window and, indirectly, the class to which the window belongs.

• nIndex
  Specifies the zero-based offset to the value to be retrieved. Valid values are in the range zero through the number of bytes of extra window memory, minus four; for example, if you specified 12 or more bytes of extra memory, a value of 8 would be an index to the third 32-bit integer. To retrieve any other value, specify one of the following values.

  Value	Description
  GWL_EXSTYLE	Retrieves the extended window styles.
  GWL_STYLE	Retrieves the window styles.
  GWL_WNDPROC	Retrieves the address of the window procedure, or a handle representing the address of the window procedure. You must use the CallWindowProc function to call the window procedure.
  GWL_ID	Retrieves the window identifier.
  GWL_USERDATA	Retrieves the 32-bit value associated with the window. Each window has a corresponding 32-bit value intended for use by the application that created the window.

  The following values are also available when the hWnd parameter identifies a dialog box.

  Value	Description
  DWL_MSGRESULT	Retrieves the return value of a message processed in the dialog box procedure.
  DWL_USER	Retrieves extra information private to the application, such as handles or pointers.

Return Value

The requested 32-bit value indicates success. Zero indicates failure. To get extended error information, call GetLastError.

Remarks

The nIndex parameter must be a multiple of 4 bytes.

Unaligned access is not supported.

Requirements

See Also

Reference

Window Class Functions
CallWindowProc
RegisterClass
SetParent
SetWindowLong
WNDCLASS