defaultvalue.md

description	title	ms.date	f1_keywords	helpviewer_keywords	ms.assetid
Learn more about: defaultvalue	defaultvalue (C++ COM Attribute)	10/02/2018	vc-attr.defaultvalue	defaultvalue attribute	efa5d050-b2cc-4d9e-9b8e-79954f218d3a

defaultvalue

Allows specification of a default value for a typed optional parameter.

Syntax

[ defaultvalue= value ]

Parameters

value
The default value for the parameter.

Remarks

The defaultvalue C++ attribute has the same functionality as the defaultvalue MIDL attribute.

Example

The following code shows an interface method using the defaultvalue attribute:

// cpp_attr_ref_defaultvalue.cpp
// compile with: /LD
#include <windows.h>

[export] typedef long HRESULT;
[export, ptr, string] typedef unsigned char * MY_STRING_TYPE;

[  uuid("479B29EE-9A2C-11D0-B696-00A0C903487A"), dual, oleautomation, helpstring("IFireTabCtrl Interface"), helpcontext(122), pointer_default(unique) ]

__interface IFireTabCtrl : IDispatch {
   [bindable, propget] HRESULT get_Size([out, retval, defaultvalue("33")] long *nSize);
   [bindable, propput] HRESULT put_Size([in] int nSize);
};

[ module(name="ATLFIRELib", uuid="479B29E1-9A2C-11D0-B696-00A0C903487A",    version="1.0", helpstring="ATLFire 1.0 Type Library") ];

Requirements

Attribute context	Value
Applies to	Interface parameter
Repeatable	No
Required attributes	None
Invalid attributes	None

For more information, see Attribute Contexts.

See also

IDL Attributes
Parameter Attributes
out
retval
in
pointer_default
unique