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defaultvalue

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

[ defaultvalue= value ]

Параметры

  • value
    The default value for the parameter.

Заметки

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

Пример

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") ];

Требования

Attribute Context

Applies to

Interface parameter

Repeatable

No

Required attributes

None

Invalid attributes

None

For more information, see Attribute Contexts.

См. также

Основные понятия

IDL Attributes

Parameter Attributes

out (C++)

retval

in (C++)

pointer_default

unique (C++)

ATL Samples