c++ - Accessing the intrinsic type hash functions for tr1/unordered_map -

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i'm messing around unordered_map class template, , i'd write custom hasher class. documentation mentions default hashing functions provided intrinsic types. so, if declare:

std::tr1::unordered_map<std::string, int> foo;

you automatically hasher defined you.

there's example on here on how provide functor if want custom hash function.

however, if have complex class has std::string member use key insertion/deletion unordered_map? don't want rewrite own hasher. want leverage written std::string type.

the default hash functor provided std::hash<t> returns size_t.

so can combine hash several members of class e.g. computing (std::hash<t>()(a) + prime * (std::hash<t>()(b) + prime * std::hash<t>()(c))).


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