Problem with operator+

[roktsyntst]

I'm writing a class to manage memory for me (mostly for the experience though). Borland 5.5.1 for Windows is giving me a weird error. Here is the class:

namespace MemoryManager {

	enum Option { printall = 1 }; // just one for now

	typedef map< void*, Object > pvomap;
	
class Mgr {

public:
	Mgr( Option opt = 0 );
	template< class T > T* alloc( int = 1 );
	template< class T > void dealloc( T* );
	int allocated( const void* ptr ) const;
	template< class T > long bytes_allocated ( const T* ) const;
	long total_allocated() const;
	long total_bytes_allocated() const;

protected:
	Option itsOptions;
	pvomap allPtrs;

};

} // end namespace MemoryManager

In the definition file, this function is giving me the following error:
Error E2094: 'operator+' not implemented in type 'pvomap' for arguments of type 'const void *'.

	int Mgr::allocated( const void* ptr ) const {

		Object foo = allPtrs[ ptr ]; // error on this line
		int bar = foo.created();
		return bar;

	}

(This is the result of breaking down the steps. Originally the function was defined with one line: "return allPtrs[ptr].created();" but I broke it down to help me find the problem. I'm still stuck - I have no idea where the operator+ has anything to do with this...any help is appreciated. Thanks.

[Magos]

I believe that the [ ] operator works so it takes the base pointer (allPtrs) then adds the relative adress (ptr) to get the effective adress. And thus, const void* doesn't have a + operator defined.
Why doing that? Indexes must be integers.

[roktsyntst]

allPtrs is not an array, but rather a std::map with first type "void *". It's subscript operator should be overloaded to take that type and return the associated Object (in this case). What puzzles me is this error ocurring here, but other functions using a similar construct do not report an error.

I also forgot to mention that the end of that function reports the following warning:
W8057: Parameter 'ptr' is never used in function Mgr::allocated(const void* const).

This is also strange, since ptr is clearing being used...I'm guessing there's an obvious syntax error that I'm just missing.

[Stoned_Coder]

const void *

do you know what that is?

do you mean

void * const

[roktsyntst]

The difference refers to whether it is the address that is constant or the value there, correct? It probably makes more sense to have void * const, but that doesn't change the issue. A search on comp.lang.c++ (http://groups.google.com/groups?hl=e...5506%40acm.org) revealed that you can't use operator[] on a const map (which is a map that is part of a const object). So I used find instead (at the recommendation there), but that said it could find no match. So I've kept the const-ness of the pointer out completely in order for it to compile...

edit: I changed const void* to void* and now to void * const, and it seems to be working. Thanks for the tip.