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title defaultvalue | Microsoft Docs
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ms.date 11/04/2016
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ms.topic language-reference
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C++
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defaultvalue attribute
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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.

See Also

IDL Attributes
Parameter Attributes
out
retval
in
pointer_default
unique