How to clear the following visual studio error?

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1.00/5 (1 vote)

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The c++ code is -

C++

// SimpleCom.cpp : Implementation of CSimpleCom

/*#include "C:\Users\georget\Documents\Visual Studio 2012\Projects\Pro1\Pro1\stdafx.h"
#include "C:\Users\georget\Documents\Visual Studio 2012\Projects\Pro1\Pro1\SimpleCom.h"
#include "stdafx.h"*/
#include "stdafx.h"
#include "SimpleCom.h"

C++

// CSimpleCom

[ClassInterface(ClassInterfaceType::AutoDispatch)]
       [ProgId(S"InteropSample::MyClass")]

STDMETHODIMP CSimpleCom::add(LONG a1, LONG a2, LONG* r)
{
	// TODO: Add your implementation code here
	*r=a1+a2;
	return S_OK;
}

the error it shows-

Error   1   error C2337: 'ClassInterface' : attribute not found 
Error   2   error C2653: 'ClassInterfaceType' : is not a class or namespace name   
Error   3   error C2065: 'AutoDispatch' : undeclared identifier c:\users\georget\documents\visual studio 2012\projects\pro1\pro1\simplecom.cpp  13  1   Pro1
Error   4   error C2337: 'ProgId' : attribute not found 
Error   5   error C3921: Use of S-prefixed strings requires /clr:oldSyntax command line option  
Error   6   error C1903: unable to recover from previous error(s); stopping compilation

Can anyone suggest how to correct it?

Posted 6-Aug-15 19:57pm

Somesh Dhal

Updated 6-Aug-15 20:37pm

CPallini

v2

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Comments

Sergey Alexandrovich Kryukov 7-Aug-15 2:32am

It looks like you are mixing C++/CLI with C++ (ATL, COM, etc.). I'm not saying you should not do it, but I'm not sure if you really need it. Now, you simply did not use correct type names. And you don't have "using" for them. Finally, you might not reference their assembly.
—SA

Jochen Arndt 7-Aug-15 2:36am

The name space is missing. At least
using namespace System::Runtime::InteropServices;
should be present (may be more name spaces).

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Sergey Alexandrovich Kryukov · Answer 1 · 2015-08-06T20:39:00

Please see my comment to the question.

Now, proper attribute name is System.Runtime::InteropServices::ClassInterfaceAttribute and it's parameter you tried to use is of the type System.Runtime.InteropServices.ClassInterfaceAttribute.
You did not use those full names ("ClassInterfaceAttribute" is usually shorted to "ClassInterface" where the attribute is applied), and you did not prescribe the namespace in using directive. So, what would you expect?

Please see:
https://msdn.microsoft.com/en-us/library/system.runtime.interopservices.classinterfaceattribute%28v=vs.100%29.aspx[^],
https://msdn.microsoft.com/en-us/library/system.runtime.interopservices.classinterfacetype%28v=vs.110%29.aspx[^].

Just write everything properly. Learn assemblies and their referencing, type naming and namespaces.

—SA