How do I implement a CString hash function for use with std::unordered_map?

Question

I want to declare :

std::unordered_map m_mapMyMap;

But when I build I got an error telling me that the standard C++

Answer 1

std::unordered_map use std::hash<> that does not use (LPCSTR) operator.

You need to redefine hash function:

template class MyHash;

template<>
class MyHash {
public:
    size_t operator()(const CString &s) const
    {
        return std::hash()( (LPCSTR)s );
    }
};

std::unordered_map m_mapMyMap;

But for better performance use std::string instead CString for key.