C++是否爲引用指定了散列函數？

Question

我的問題很快。

請問C++標準庫實現對引用的哈希函數，如std::hash<T&>

Answer 1

不，不。在[function.objects]列舉的專業有：

// Hash function specializations 
template <> struct hash<bool>; 
template <> struct hash<char>; 
template <> struct hash<signed char>; 
template <> struct hash<unsigned char>; 
template <> struct hash<char16_t>; 
template <> struct hash<char32_t>; 
template <> struct hash<wchar_t>; 
template <> struct hash<short>; 
template <> struct hash<unsigned short>; 
template <> struct hash<int>; 
template <> struct hash<unsigned int>; 
template <> struct hash<long>; 
template <> struct hash<long long>; 
template <> struct hash<unsigned long>; 
template <> struct hash<unsigned long long>; 

template <> struct hash<float>; 
template <> struct hash<double>; 
template <> struct hash<long double>; 

template<class T> struct hash<T*>; 

而且，你會這樣的事情，即使是什麼意思？