Standard Template Library Programmer's Guide

[1] Multimap::iterator is not a mutable iterator, because multimap::value_type is not Assignable. That is, if i is of type multimap::iterator and p is of type multimap::value_type , then *i = p is not a valid expression. However, multimap::iterator isn't a constant iterator either, because it can be used to modify the object that it points to. Using the same notation as above, (*i).second = p is a valid expression. The same point applies to multimap::reverse_iterator .

[2] This member function relies on member template functions, which at present (early 1998) are not supported by all compilers. If your compiler supports member templates, you can call this function with any type of input iterator. If your compiler does not yet support member templates, though, then the arguments must either be of type const value_type* or of type multimap::const_iterator .

Associative Container, Sorted Associative Container, Pair Associative Container, Multiple Sorted Associative Container, set , map, multiset , hash_set , hash_map , hash_multiset , hash_multimap

Category: containers

Component type: type

Hash_set is a Hashed Associative Container that stores objects of type Key . Hash_set is a Simple Associative Container, meaning that its value type, as well as its key type, is Key . It is also a Unique Associative Container, meaning that no two elements compare equal using the Binary Predicate EqualKey .

Hash_set is useful in applications where it is important to be able to search for an element quickly. If it is important for the elements to be in a particular order, however, then set is more appropriate.

struct eqstr {

bool operator()(const char* s1, const char* s2) const {

return strcmp(s1, s2) == 0;

}

};

void lookup(const hash_set, eqstr>& Set, const char* word) {

hash_set, eqstr>::const_iterator it = Set.find(word);

cout << word << ": " << (it != Set.end() ? "present" : "not present") << endl;

}

int main() {

hash_set, eqstr> Set;

Set.insert("kiwi");

Set.insert("plum");

Set.insert("apple");

Set.insert("mango");

Set.insert("apricot");

Set.insert("banana");

lookup(Set, "mango");

lookup(Set, "apple");

lookup(Set, "durian");

}

Defined in the header hash_set, and in the backward-compatibility header hash_set.h. This class is an SGI extension; it is not part of the C++ standard.

Unique Hashed Associative Container, Simple Associative Container

• Key is Assignable.

• EqualKey is a Binary Predicate whose argument type is Key .

• EqualKey is an equivalence relation.

• Alloc is an Allocator.

None.

All of hash_set 's members are defined in the Unique Hashed Associative Container and Simple Associative Container requirements. Hash_set does not introduce any new members.