
ALINK="#ff0000">
set<Key, Compare, Alloc>


Category: containers 
Component type: type 
Description
Set is a
Sorted Associative Container that stores objects of type Key.
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 are the same.
Set and multiset are
particularly well suited to the set algorithms
includes,
set_union,
set_intersection,
set_difference, and
set_symmetric_difference.
The reason for this is twofold. First, the set algorithms require
their arguments to be sorted ranges, and, since
set and
multiset are
Sorted Associative Containers,
their elements are always sorted in ascending order.
Second, the output range of these algorithms is always sorted, and
inserting a sorted range into a set or multiset is a
fast operation: the
Unique Sorted Associative Container
and Multiple Sorted Associative Container
requirements guarantee that inserting a
range takes only linear time if the range is already sorted.
Set has the important property that inserting a new element
into a set does not invalidate iterators that point to existing
elements. Erasing an element from a set also does not invalidate
any iterators, except, of course, for iterators that actually point
to the element that is being erased.
Example
struct ltstr
{
bool operator()(const char* s1, const char* s2) const
{
return strcmp(s1, s2) < 0;
}
};
int main()
{
const int N = 6;
const char* a[N] = {"isomer", "ephemeral", "prosaic",
"nugatory", "artichoke", "serif"};
const char* b[N] = {"flat", "this", "artichoke",
"frigate", "prosaic", "isomer"};
set<const char*, ltstr> A(a, a + N);
set<const char*, ltstr> B(b, b + N);
set<const char*, ltstr> C;
cout << "Set A: ";
copy(A.begin(), A.end(), ostream_iterator<const char*>(cout, " "));
cout << endl;
cout << "Set B: ";
copy(B.begin(), B.end(), ostream_iterator<const char*>(cout, " "));
cout << endl;
cout << "Union: ";
set_union(A.begin(), A.end(), B.begin(), B.end(),
ostream_iterator<const char*>(cout, " "),
ltstr());
cout << endl;
cout << "Intersection: ";
set_intersection(A.begin(), A.end(), B.begin(), B.end(),
ostream_iterator<const char*>(cout, " "),
ltstr());
cout << endl;
set_difference(A.begin(), A.end(), B.begin(), B.end(),
inserter(C, C.begin()),
ltstr());
cout << "Set C (difference of A and B): ";
copy(C.begin(), C.end(), ostream_iterator<const char*>(cout, " "));
cout << endl;
}
Definition
Defined in the standard header set, and in the nonstandard
backwardcompatibility header set.h.
Template parameters
Parameter

Description

Default

Key

The set's key type and value type. This is also defined as set::key_type
and set::value_type


Compare

The key comparison function, a Strict Weak Ordering whose
argument type is key_type; it returns true if its first
argument is less than its second argument, and false otherwise.
This is also defined as set::key_compare and set::value_compare.

less<Key>

Alloc

The set's allocator, used for all internal memory management.

alloc

Model of
Unique Sorted Associative Container,
Simple Associative Container
Type requirements
Public base classes
None.
Members
Member

Where defined

Description

value_type

Container

The type of object, T, stored in the set.

key_type

Associative Container

The key type associated with value_type.

key_compare

Sorted Associative Container

Function object that compares two keys for ordering.

value_compare

Sorted Associative Container

Function object that compares two values for ordering.

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 set.

const_iterator

Container

Const iterator used to iterate through a set. (Iterator and
const_iterator are the same type.)

reverse_iterator

Reversible Container

Iterator used to iterate backwards through a set.

const_reverse_iterator

Reversible Container

Const iterator used to iterate backwards through a set.
(Reverse_iterator and const_reverse_iterator are the same type.)

iterator begin() const

Container

Returns an iterator pointing to the beginning of the set.

iterator end() const

Container

Returns an iterator pointing to the end of the set.

reverse_iterator rbegin() const

Reversible Container

Returns a reverse_iterator pointing to the beginning of the
reversed set.

reverse_iterator rend() const

Reversible Container

Returns a reverse_iterator pointing to the end of the
reversed set.

size_type size() const

Container

Returns the size of the set.

size_type max_size() const

Container

Returns the largest possible size of the set.

bool empty() const

Container

true if the set's size is 0.

key_compare key_comp() const

Sorted Associative Container

Returns the key_compare object used by the set.

value_compare value_comp() const

Sorted Associative Container

Returns the value_compare object used by the set.

set()

Container

Creates an empty set.

set(const key_compare& comp)

Sorted Associative Container

Creates an empty set, using comp as the key_compare object.

template <class InputIterator>
set(InputIterator f, InputIterator l)
[1]

Unique Sorted Associative Container

Creates a set with a copy of a range.

template <class InputIterator>
set(InputIterator f, InputIterator l,
const key_compare& comp)
[1]

Unique Sorted Associative Container

Creates a set with a copy of a range, using comp as the key_compare
object.

set(const set&)

Container

The copy constructor.

set& operator=(const set&)

Container

The assignment operator

void swap(set&)

Container

Swaps the contents of two sets.

pair<iterator, bool>
insert(const value_type& x)

Unique Associative Container

Inserts x into the set.

iterator insert(iterator pos,
const value_type& x)

Unique Sorted Associative Container

Inserts x into the set, using pos as a hint to where it will be
inserted.

template <class InputIterator>
void insert(InputIterator, InputIterator)
[1]

Unique Sorted Associative Container

Inserts a range into the 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.

iterator lower_bound(const key_type& k) const

Sorted Associative Container

Finds the first element whose key is not less than k.

iterator upper_bound(const key_type& k) const

Sorted Associative Container

Finds the first element whose key greater than k.

pair<iterator, iterator>
equal_range(const key_type& k) const

Sorted Associative Container

Finds a range containing all elements whose key is k.

bool operator==(const set&,
const set&)

Forward Container

Tests two sets for equality. This is a global function, not
a member function.

bool operator<(const set&,
const set&)

Forward Container

Lexicographical comparison. This is a global function, not
a member function.

New members
All of set's members are defined in the
Unique Sorted Associative Container
and Simple Associative Container
requirements. 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
set::const_iterator.
See also
Associative Container,
Sorted Associative Container,
Simple Associative Container,
Unique Sorted Associative Container,
map,
multiset,
multimap,
hash_set,
hash_map,
hash_multiset,
hash_multimap
Copyright ©
1999 Silicon Graphics, Inc. All Rights Reserved.
TrademarkInformation
