Re: CMap and struct

David Wilkinson <>
Thu, 03 May 2007 10:32:38 -0500
Vahid wrote:

Thanks a lot guys for your suggestions. Since I'm not used to standard
library (compared to MFC), I picked CMap right away. And before
reading your messages, I had come up with the following which compiled

struct SDataType {
    unsigned long nNamespace;
    unsigned long nDataType;
    SDataType& operator=(SDataType s2) { nNamespace = s2.nNamespace;
nDataType = s2.nDataType; return *this; }
    bool operator==(SDataType s2) const { return ((nNamespace ==
s2.nNamespace) && (nDataType == s2.nDataType)); }

template<> AFX_INLINE UINT AFXAPI HashKey(SDataType& key)
    return HashKey((DWORD_PTR) key.nNamespace) + HashKey ((DWORD_PTR)

Arman, how do you compare this with your suggestion. As you see, I do
not use reference parameters here.


I think all these methods should be taking const SDataType& as argument.
Actually, you do not need operator =(), because you are just doing
member-wise assignment, which is what the default implementation does.

Again, IMHO, before you get too deeply involved in the MFC collection
classes, consider the C++ library ones instead.

David Wilkinson
Visual C++ MVP

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