hash<T> hash<T> Categories: containers, functors Component type: type Description The function object hash<T> is a Hash Function; it is used as the default hash function by all of the Hashed Associative Containers that are included in the STL. The hash<T> template is only defined for template arguments of type char*, const char*, crope, wrope, and the built-in integral types. [1] If you need a Hash Function with a different argument type, you must either provide your own template specialization or else use a different Hash Function. Example int main() { hash<const char*> H; cout << "foo -> " << H("foo") << endl; cout << "bar -> " << H("bar") << endl; } Definition Defined in the headers hash_map and hash_set, and in the backward-compatibility headers hash_map.h and hash_set.h. This class is an SGI extension; it is not part of the C++ standard. Template parameters Parameter Description Default T The argument type. That is, the type of object that is being hashed.   Model of Hash Function Type requirements T must be a type for which a specialization of hash has been defined. The STL defines the following specializations: char* const char* crope wrope char signed char unsigned char short unsigned short int unsigned int long unsigned long Public base classes None. Members Member Where defined Description size_t operator()(const T& x) Hash Function Returns x's hash value. New members All of hash's members are defined in the Hash Function requirements. Hash does not introduce any new members. Notes [1] Technically, what this means is that the actual template hash<T> is an empty class; the member function operator() is defined only in the various specializations. See also Hashed Associative Container, Hash Function Copyright © 1999 Silicon Graphics, Inc. All Rights Reserved. TrademarkInformation