hash_set<Key, HashFcn, EqualKey, Alloc>
hash_set<Key, HashFcn, EqualKey, Alloc>
Category: containers
Component type: type
Description
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.
Example
struct eqstr
{
bool operator()(const char* s1, const char* s2) const
{
return strcmp(s1, s2) == 0;
}
};
void lookup(const hash_set<const char*, hash<const char*>, eqstr>& Set,
const char* word)
{
hash_set<const char*, hash<const char*>, eqstr>::const_iterator it
= Set.find(word);
cout << word << ": "
<< (it != Set.end() ? "present" : "not present")
<< endl;
}
int main()
{
hash_set<const char*, hash<const char*>, 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");
}
Definition
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.
Template parameters
Parameter
Description
Default
Key
The hash_set's key type and value type. This is also defined as hash_set::key_type
and hash_set::value_type
HashFcn
The Hash Function used by the hash_set. This is also defined
as hash_set::hasher.
hash<Key>
EqualKey
The hash_set's key equality function: a binary predicate that
determines whether two keys are equal. This is also defined as
hash_set::key_equal.
equal_to<Key>
Alloc
The hash_set's allocator, used for all internal memory management.
alloc
Model of
Unique Hashed Associative Container,
Simple Associative Container
Type requirements
Key is Assignable.
EqualKey is a Binary Predicate whose argument type
is Key.
EqualKey is an equivalence relation.
Alloc is an Allocator.
Public base classes
None.
Members
Member
Where defined
Description
value_type
Container
The type of object, T, stored in the hash_set.
key_type
Associative Container
The key type associated with value_type.
hasher
Hashed Associative Container
The hash_set's Hash Function.
key_equal
Hashed Associative Container
Function object that compares keys for equality.
pointer
Container
Pointer to T.
reference
Container
Reference to T
const_reference
Container
Const reference to T
size_type
Container
An unsigned integral type.
difference_type
Container
A signed integral type.
iterator
Container
Iterator used to iterate through a hash_set.
const_iterator
Container
Const iterator used to iterate through a hash_set. (Iterator and
const_iterator are the same type.)
iterator begin() const
Container
Returns an iterator pointing to the beginning of the hash_set.
iterator end() const
Container
Returns an iterator pointing to the end of the hash_set.
size_type size() const
Container
Returns the size of the hash_set.
size_type max_size() const
Container
Returns the largest possible size of the hash_set.
bool empty() const
Container
true if the hash_set's size is 0.
size_type bucket_count() const
Hashed Associative Container
Returns the number of buckets used by the hash_set.
void resize(size_type n)
Hashed Associative Container
Increases the bucket count to at least n.
hasher hash_funct() const
Hashed Associative Container
Returns the hasher object used by the hash_set.
key_equal key_eq() const
Hashed Associative Container
Returns the key_equal object used by the hash_set.
hash_set()
Container
Creates an empty hash_set.
hash_set(size_type n)
Hashed Associative Container
Creates an empty hash_set with at least n buckets.
hash_set(size_type n,
const hasher& h)
Hashed Associative Container
Creates an empty hash_set with at least n buckets, using h
as the hash function.
hash_set(size_type n,
const hasher& h,
const key_equal& k)
Hashed Associative Container
Creates an empty hash_set with at least n buckets, using h
as the hash function and k as the key equal function.
template <class InputIterator>
hash_set(InputIterator f, InputIterator l)
[1]
Unique Hashed Associative Container
Creates a hash_set with a copy of a range.
template <class InputIterator>
hash_set(InputIterator f, InputIterator l,
size_type n)
[1]
Unique Hashed Associative Container
Creates a hash_set with a copy of a range and a bucket count of at
least n.
template <class InputIterator>
hash_set(InputIterator f, InputIterator l,
size_type n, const hasher& h)
[1]
Unique Hashed Associative Container
Creates a hash_set with a copy of a range and a bucket count of at
least n, using h as the hash function.
hash_set(InputIterator f, InputIterator l,
size_type n, const hasher& h,
const key_equal& k)
[1]
Unique Hashed Associative Container
Creates a hash_set with a copy of a range and a bucket count of at
least n, using h as the hash function and k as the
key equal function.
hash_set(const hash_set&)
Container
The copy constructor.
hash_set& operator=(const hash_set&)
Container
The assignment operator
void swap(hash_set&)
Container
Swaps the contents of two hash_sets.
pair<iterator, bool>
insert(const value_type& x)
Unique Associative Container
Inserts x into the hash_set.
template <class InputIterator>
void insert(InputIterator f, InputIterator l)
[1]
Unique Associative Container
Inserts a range into the hash_set.
void erase(iterator pos)
Associative Container
Erases the element pointed to by pos.
size_type erase(const key_type& k)
Associative Container
Erases the element whose key is k.
void erase(iterator first, iterator last)
Associative Container
Erases all elements in a range.
void clear()
Associative Container
Erases all of the elements.
iterator find(const key_type& k) const
Associative Container
Finds an element whose key is k.
size_type count(const key_type& k) const
Unique Associative Container
Counts the number of elements whose key is k.
pair<iterator, iterator>
equal_range(const key_type& k) const
Associative Container
Finds a range containing all elements whose key is k.
bool operator==(const hash_set&,
const hash_set&)
Hashed Associative Container
Tests two hash_sets for equality. This is a global function,
not a member function.
New members
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.
Notes
[1]
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
hash_set::const_iterator.
See also
Associative Container,
Hashed Associative Container,
Simple Associative Container,
Unique Hashed Associative Container,
set,
map,
multiset,
multimap,
hash_map,
hash_multiset,
hash_multimap
Copyright ©
1999 Silicon Graphics, Inc. All Rights Reserved.
TrademarkInformation
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