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Compiler Error C2861

Error Message

'function name' : an interface member function cannot be defined

The compiler encountered the interface keyword or deduced a struct as an interface but then found a member function definition. An interface cannot contain a definition for a member function.

Example

The following sample generates C2861:

// C2861.cpp
// compile with: /c
#include <objbase.h>   // required for IUnknown definition
[ object, uuid("00000000-0000-0000-0000-000000000001") ]
__interface IMyInterface : IUnknown {
   HRESULT mf(int a);
};

HRESULT IMyInterface::mf(int a) {}   // C2861

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