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Function hash_value

boost::hash_value — Implementation of the hash function.

Synopsis

std::size_t hash_value(int val);
std::size_t hash_value(unsigned int val);
std::size_t hash_value(long val);
std::size_t hash_value(unsigned long val);
std::size_t hash_value(float val);
std::size_t hash_value(double val);
std::size_t hash_value(long double val);
template<typename T> std::size_t hash_value(T* const& val);
template<typename T, unsigned N> std::size_t hash_value(T (&val)[N]);
template<typename T, unsigned N> std::size_t hash_value(const T (&val)[N]);
template<typename Ch, typename A> 
std::size_t hash_value(std::basic_string<Ch, std::char_traits<Ch>, A> const& val);
template<typename A, typename B> 
std::size_t hash_value(std::pair<A, B> const& val);
template<typename T, typename A> 
std::size_t hash_value(std::vector<T, A> const& val);
template<typename T, typename A> 
std::size_t hash_value(std::list<T, A> const& val);
template<typename T, typename A> 
std::size_t hash_value(std::deque<T, A> const& val);
template<typename K, typename C, typename A> 
std::size_t hash_value(std::set<K, C, A> const& val);
template<typename K, typename C, typename A> 
std::size_t hash_value(std::multiset<K, C, A> const& val);
template<typename K, typename T, typename C, typename A> 
std::size_t hash_value(std::map<K, T, C, A> const& val);
template<typename K, typename T, typename C, typename A> 
std::size_t hash_value(std::multimap<K, T, C, A> const& val);

Description

Generally shouldn't be called directly by users, instead they should use boost::hash, boost::hash_range or boost::hash_combine which call hash_value without namespace qualification so that overloads for custom types are found via ADL.

Notes:

This is an extension to TR1

Throws: Only throws if a user supplied version of hash_value throws for an element of a container, or one of the types stored in a pair.
Returns:
Types Returns
int, unsigned int, long, unsigned long val
float, double, long double An unspecified value, except that equal arguments shall yield the same result.
T* An unspecified value, except that equal arguments shall yield the same result.
Tval[N], constTval[N] hash_range(val, val+N)
std:basic_string<Ch,std::char_traits<Ch>,A>, std::vector<T,A>, std::list<T,A>, std::deque<T,A>, std::set<K,C,A>, std::multiset<K,C,A>, std::map<K,T,C,A>, std::multimap<K,T,C,A> hash_range(val.begin(), val.end())
std::pair<A, B>
size_t seed = 0;
hash_combine(seed, val.first);
hash_combine(seed, val.second);
return seed;
Copyright 2005, 2006 Daniel James

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