RegisterClassEx function

Applies to: desktop apps only

Registers a window class for subsequent use in calls to the CreateWindow or CreateWindowEx function.

Syntax

ATOM WINAPI RegisterClassEx(
  __in  const WNDCLASSEX *lpwcx
);

Parameters

lpwcx [in]

Type: const WNDCLASSEX*

A pointer to a WNDCLASSEX structure. You must fill the structure with the appropriate class attributes before passing it to the function.

Return value

Type:

Type: ATOM

If the function succeeds, the return value is a class atom that uniquely identifies the class being registered. This atom can only be used by the CreateWindow, CreateWindowEx, GetClassInfo, GetClassInfoEx, FindWindow, FindWindowEx, and UnregisterClass functions and the IActiveIMMap::FilterClientWindows method.

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

Remarks

If you register the window class by using RegisterClassExA, the application tells the system that the windows of the created class expect messages with text or character parameters to use the ANSI character set; if you register it by using RegisterClassExW, the application requests that the system pass text parameters of messages as Unicode. The IsWindowUnicode function enables applications to query the nature of each window. For more information on ANSI and Unicode functions, see Conventions for Function Prototypes.

All window classes that an application registers are unregistered when it terminates.

No window classes registered by a DLL are unregistered when the DLL is unloaded. A DLL must explicitly unregister its classes when it is unloaded.

Examples

For an example, see Using Window Classes.

Requirements

See also

Reference

CreateWindow

CreateWindowEx

FindWindow

FindWindowEx

GetClassInfo

GetClassInfoEx

GetClassName

RegisterClass

UnregisterClass

WindowProc

WNDCLASSEX

Conceptual

Window Classes

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Build date: 2/3/2012