GetClassInfoExW function (winuser.h)

Article
02/09/2023

Retrieves information about a window class, including a handle to the small icon associated with the window class. The GetClassInfo function does not retrieve a handle to the small icon.

Syntax

BOOL GetClassInfoExW(
  [in, optional] HINSTANCE     hInstance,
  [in]           LPCWSTR       lpszClass,
  [out]          LPWNDCLASSEXW lpwcx
);

Parameters

[in, optional] hInstance

Type: HINSTANCE

A handle to the instance of the application that created the class. To retrieve information about classes defined by the system (such as buttons or list boxes), set this parameter to NULL.

[in] lpszClass

Type: LPCTSTR

The class name. The name must be that of a preregistered class or a class registered by a previous call to the RegisterClass or RegisterClassEx function. Alternatively, this parameter can be a class atom created by a previous call to RegisterClass or RegisterClassEx. The atom must be in the low-order word of lpszClass; the high-order word must be zero.

[out] lpwcx

Type: LPWNDCLASSEX

A pointer to a WNDCLASSEX structure that receives the information about the class.

Return value

Type: BOOL

If the function finds a matching class and successfully copies the data, the return value is nonzero.

If the function does not find a matching class and successfully copy the data, the return value is zero. To get extended error information, call GetLastError.

Remarks

Class atoms are created using the RegisterClass or RegisterClassEx function, not the GlobalAddAtom function.

Note

The winuser.h header defines GetClassInfoEx as an alias which automatically selects the ANSI or Unicode version of this function based on the definition of the UNICODE preprocessor constant. Mixing usage of the encoding-neutral alias with code that not encoding-neutral can lead to mismatches that result in compilation or runtime errors. For more information, see Conventions for Function Prototypes.

Requirements

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
API set	ext-ms-win-ntuser-windowclass-l1-1-0 (introduced in Windows 8)