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4/8/2010

This function retrieves the specified 32-bit (long) value from the WNDCLASSstructure associated with the specified window.

Syntax 

DWORD GetClassLong( 
  HWND 
hWnd, 
  int 
nIndex
);

Parameters

hWnd

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

nIndex

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

Value Description

GCW_ATOM

Retrieves an ATOMvalue that uniquely identifies the window class. This is the same atom that the RegisterClassfunction returns.

GCL_CBCLSEXTRA

Retrieves the size, in bytes, of the extra memory associated with the class.

GCL_CBWNDEXTRA

Retrieves the size, in bytes, of the extra window memory associated with each window in the class. For information on how to access this memory, see GetWindowLong.

GCL_HBRBACKGROUND

Retrieves a handle to the background brush associated with the class.

GCL_HCURSOR

Retrieves a handle to the cursor associated with the class.

GCL_HICON

Retrieves a handle to the icon associated with the class.

GCL_HICONSM

Retrieves a handle to the small icon associated with the class.

GCL_HMODULE

Retrieves a handle to the module that registered the class.

GCL_MENUNAME

Retrieves the address of the menu name string. The string identifies the menu resource associated with the class.

GCL_STYLE

Retrieves the window-class style bits.

GCL_WNDPROC

Retrieves the address of the window procedure associated with the class.

Return Value

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

Remarks

The nIndexparameter is a byte offset but must be a multiple of 4 bytes. Windows Embedded CE does not support unaligned access.

The only values supported for the nIndexparameter are GCL_HICON and GCL_STYLE.

If you are using the Windows Embedded CE Iconcurs component, which supports mouse cursors on appropriate target platforms, you can also use the GCL_HCURSOR value in the nIndexparameter.

Windows Embedded CE versions that support mouse cursors include the Iconcurs and Mcursor components rather than the Icon and Cursor components.

Reserve extra class memory by specifying a nonzero value in the cbClsExtramember of the WNDCLASSstructure used with the RegisterClassfunction.

Requirements

Header winuser.h
Windows Embedded CE Windows CE 1.0 and later
Windows Mobile Windows Mobile Version 5.0 and later

See Also