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GetWindowLong

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

VB4-32,5,6
Declare Function GetWindowLong Lib "user32" Alias "GetWindowLongA" (ByVal hwnd As Long, ByVal nIndex As Long) As Long

Operating Systems Supported
Requires Windows NT 3.1 or later; Requires Windows 95 or later

Library
User32

Parameter Information
hWnd
Identifies 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:
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_HINSTANCE
Retrieves the handle of the application instance.
GWL_HWNDPARENT
Retrieves the handle of the parent window, if any.
GWL_ID
Retrieves the identifier of the window.
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:
DWL_DLGPROC
Retrieves the address of the dialog box procedure, or a handle representing the address of the dialog box procedure. You must use the CallWindowProc function to call the dialog box procedure.
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 Values
If the function succeeds, the return value is the requested 32-bit value.

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

Examples

Related Functions

 

 


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