GetWindowLong
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4/8/2010
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.
A remote application interface (RAPI) version of this function exists, and it is called CeGetWindowLong (RAPI).
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. Windows CE 2.0 and later support this value, but Windows CE 1.0 and 1.01 do not.
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.
Windows CE 1.0 and 1.01 also do not support the DWL_DLGPROC value in the nIndex parameter.
Requirements
| Header | winuser.h |
| Windows Embedded CE | Windows CE 1.0 and later |
| Windows Mobile | Windows Mobile Version 5.0 and later |
See Also
Reference
Window Class Functions
CallWindowProc
RegisterClass
SetParent
SetWindowLong
WNDCLASS