C++ Interface

Hello everyone,


Just wondering how COM implementation uses keyword interface without compile error, for a normal C++ project, if we use keyword interface, there will be compile error.

Code:

interface IFoo {
	
	int func() = 0;
};

Compile error:

--------------------
1>d:\visual studio 2008\projects\test_virtual1\test_virtual1\main2.cp p(1) : error C2146: syntax error : missing ';' before identifier 'IFoo'
1>d:\visual studio 2008\projects\test_virtual1\test_virtual1\main2.cp p(1) : error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
1>d:\visual studio 2008\projects\test_virtual1\test_virtual1\main2.cp p(1) : error C2470: 'IFoo' : looks like a function definition, but there is no parameter list; skipping apparent body
--------------------

Any ideas?


thanks in advance,
George

I don't do .NET, but my beginner's C++ book has 1 age on .NET and says the MS keyword is

Code:

__interface

The error messages appear to me like the interface keyword you are using is not recognized.

Could it be?

I don't know anything about COM, but there is no interface keyword in C++. Maybe it's a Microsoft extension or a macro for something like the class keyword?

Hi Todd,


You are doing managed C++? But I am doing non-managed C++.

Originally Posted by Todd Burch

I don't do .NET, but my beginner's C++ book has 1 age on .NET
and says the MS keyword is

Code:

__interface

The error messages appear to me like the interface keyword you are using is not recognized.

Could it be?

regards,
George

Yes, cpjust!


Interface is not a part of C++ Spec, I think Visual Studio defines it to struct.

Originally Posted by cpjust

I don't know anything about COM, but there is no interface keyword in C++. Maybe it's a Microsoft extension or a macro for something like the class keyword?

regards,
George

I looked it up on MSDN. Just as I suspected - it requires two underscores in front the keyword:

http://msdn2.microsoft.com/en-us/lib...tb(VS.71).aspx

Todd

See this too if you want to use the interface keyword without the two underscores:

http://msdn2.microsoft.com/en-us/library/ms858713.aspx

Originally Posted by George2

You are doing managed C++?

Nope. Not me.

Thanks for your great links!


My question is answered.

Originally Posted by Todd Burch

Nope. Not me.

regards,
George