defaultvalue

Articolo
01/03/2018

The latest version of this topic can be found at 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

Applies to	Interface parameter
Repeatable	No
Required attributes	None
Invalid attributes	None

For more information, see Attribute Contexts.

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