I have looked for dupes of this but forgive me if I missed a solution.
I have a smart pointer that has 2 comparison overloads, "==" and "<". Both of these operate on the underlying pointer only (inherited code before I am chastised). However on compilation I am getting a C2244 error for both. I will present the case for the equality operator only as the other is almost exactly the same:
Error 4 error C2244: 'SmartRef::operator ==' : unable to match function definition to an existing declaration q:\projs\ha\src\SmartRef.cpp 114
The following code works fine in VC4.2 (I am porting to VC2008... courage).
SmartRef.h
#ifndef HA_INCL_REFERENCE
#define HA_INCL_REFERENCE 1
template <class TypeRefObj>
class SmartRef
{
public:
//@cmember Default constructor
inline SmartRef();
//@cmember Constructor
inline SmartRef( TypeRefObj * pThePointer );
//@cmember Destructor
inline ~SmartRef();
//@cmember Copy constructor
inline SmartRef( const NIEB_clReference< TypeRefObj > & roTheValue );
//@cmember
inline const SmartRef< TypeRefObj > & operator= ( const SmartRef< TypeRefObj > & roTheValue );
//@cmember
inline SmartRef< TypeRefObj > & operator= ( const SmartRef * pTheValue );
//@cmember
inline int operator== ( const SmartRef< TypeRefObj > & roTheValue ) const;
//@cmember
inline int operator< ( const SmartRef< TypeRefObj > & roTheValue ) const;
//@cmember
inline TypeRefObj & operator* () const;
开发者_如何学C //@cmember
inline TypeRefObj * operator-> () const;
private:
//@cmember Reference pointer
TypeRefObj * m_pRefPointer;
};
#include "SmartRef.cpp"
#endif //HA_INCL_REFERENCE
SmartRef.cpp
template <class TypeRefObj>
inline int SmartRef< TypeRefObj >::operator==
( SmartRef< TypeRefObj > & roTheValue ) const
{
return m_pRefPointer == roTheValue.m_pRefPointer;
}
My first thought was that there was a problem because there was no comparison in the specialised classes, but then I realised that I am comparing pointers not objects. Then I thought maybe I need to be very explicit about that so I case both sides of the comparison to `void* but that made no difference. So now I am thinking that there is some reason that the definition is not valid in VC 2008. But I cannot for the life of me figure out what is wrong with the definition.
Any help is much appreciated. Thanks, Dennis.
*EDIT:*I'm embarrassed that it was so simple. I was missing a const from the definition. Thanks all, I don't know how I failed to spot it! Prize goes to first correct answer.
You have omitted the const from the function in SmartPtr.cpp
template <class TypeRefObj>
inline int SmartRef< TypeRefObj >::operator== ( const SmartRef< TypeRefObj > & roTheValue ) const
{
return m_pRefPointer == roTheValue.m_pRefPointer;
}
Works
You're lacking a const
in the definition.
template <class TypeRefObj>
inline int SmartRef< TypeRefObj >::operator==
( const SmartRef< TypeRefObj > & roTheValue ) const
Also, you should define the member functions in the header - #include
of a .cpp like you do doesn't do much for readability.
Templates don't belong in a .cpp
file, they belong in a header too, because the compiler needs to know the full code to instantiate templates of it. Then, you are missing the const
in the definition of your operator==
. Also, all comparision operators should return bool
, not int
.
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