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set(3C++)			       -			     set(3C++)

Standard C++ Library Copyright 1998, Rogue Wave Software, Inc.

NAME
       set

	-  An  associative container that supports unique keys. A set supports
       bidirectional iterators.

SYNOPSIS
#include <set>
template <;class Key, class Compare = less<Key>,
class Allocator = allocator<Key> >
class set ;

DESCRIPTION
       set<Key,_Compare,_Allocator>_is an associative container that  supports
       unique  keys and allows for fast retrieval of the keys. A set contains,
       at most, one of any key value. The keys are sorted using Compare.

       Since a set maintains a total order on its elements, you	 cannot	 alter
       the  key values directly. Instead, you must insert new elements with an
       insert_iterator.

       Any type used for the template parameter Key must include the following
       (where T is the type, t is a value of T and u is a const value of T):

       Copy constructors   T(t) and T(u)

       Destructor   t.~T()

       Address of   &t and &u yielding T* and const T* respectively

       Assignment   t = a where a is a (possibly const) value of T

       The  type  used	for  the  Compare  template parameter must satisfy the
       requirements for binary functions.

INTERFACE
       template <class Key, class Compare = less<Key>,
       class Allocator = allocator<Key> >
       class set {
       public:
       // types
       typedef Key key_type;
       typedef Key value_type;
       typedef Compare key_compare;
       typedef Compare value_compare;
       typedef Allocator allocator_type;
       typedef typename Allocator::reference reference;
       typedef typename Allocator::const_reference const_reference;
       class iterator;
       class const_iterator;
       typedef typename Allocator::size_type size_type;
       typedef typename Allocator::difference_type difference_type;
       typedef typename std::reverse_iterator<iterator>
		     reverse_iterator;
typedef typename std::reverse_iterator<;const_iterator>
		     const_reverse_iterator;

// Construct/Copy/Destroy
explicit set (const Compare& = Compare(),
	     const Allocator& = Allocator ());
template <;class InputIterator>
set (InputIterator, InputIterator,
    const Compare& = Compare(),
    const Allocator& = Allocator ());
set (const set<;Key, Compare, Allocator>&);
~set ();
set<;Key, Compare, Allocator>& operator=
   (const set <Key, Compare, Allocator>&);
allocator_type get_allocator () const;

// Iterators
iterator begin ();
const_iterator begin () const;
iterator end ();
const_iterator end () const;
reverse_iterator rbegin ();
const_reverse_iterator rbegin () const;
reverse_iterator rend ();
const_reverse_iterator rend () const;

// Capacity
bool empty () const;
size_type size () const;
size_type max_size () const;

// Modifiers
pair<;iterator, bool> insert (const value_type&);
iterator insert (iterator, const value_type&);
template <;class InputIterator>
void insert (InputIterator, InputIterator);
void erase (iterator);
size_type erase (const key_type&);
void erase (iterator, iterator);
void swap (set<;Key, Compare, Allocator>&);
void clear ();

// Observers
key_compare key_comp () const;
value_compare value_comp () const;

// Set operations
size_type count (const key_type&) const;
pair<;iterator, iterator> equal_range (const  key_type&) const;
iterator find (const key_type&) const;
iterator lower_bound (const key_type&) const;
iterator upper_bound (const key_type&) const
};

// Non-member Operators
template <;class Key, class Compare, class Allocator>
bool operator== (const set<Key, Compare, Allocator>&,
const set<;Key, Compare, Allocator>&);
template <;class Key, class Compare, class Allocator>
bool operator!= (const set<Key, Compare, Allocator>&,
const set<;Key, Compare, Allocator>&);
template <;class Key, class Compare, class Allocator>
bool operator<; (const set<Key, Compare, Allocator>&,
const set<;Key, Compare, Allocator>&);
template <;class Key, class Compare, class Allocator>
bool operator> (const set<Key, Compare, Allocator>&,
const set<;Key, Compare, Allocator>&);
template <;class Key, class Compare, class Allocator>
bool operator<;= (const set<Key, Compare, Allocator>&,
const set<;Key, Compare, Allocator>&);
template <;class Key, class Compare, class Allocator>
bool operator>= (const set<Key, Compare, Allocator>&,
const set<;Key, Compare, Allocator>&);

// Specialized Algorithms
template <;class Key, class Compare, class Allocator>
void swap (set <;Key, Compare, Allocator>&,
set <;Key, Compare, Allocator>&);

CONSTRUCTORS
       explicit
       set(const Compare& comp = Compare(),
       const Allocator& alloc = Allocator());

   Creates a set of zero elements. If the function object comp is supplied, it
   is  used  to compare elements of the set.   Otherwise, the default function
   object in the template argument is used. The template argument defaults  to
   less (<). The allocator alloc is used for all storage management.

template <;class InputIterator>
set(InputIterator first, InputIterator last,
const Compare& comp = Compare()
const Allocator& alloc = Allocator());

   Creates  a  set  of length last - first, filled with all values obtained by
   dereferencing the InputIterators on the range [first, last). If  the	 func‐
   tion	 object	 comp  is supplied, it is used to compare elements of the set.
   Otherwise, the default function object in the template  argument  is	 used.
   The	template argument defaults to less (<). Uses the allocator Allocator()
   for all storage management.

set(const set<;Key, Compare, Allocator>& x);

   Copy constructor. Creates a copy of x.

DESTRUCTORS
       ~set();

   Releases any allocated memory for self.

ASSIGNMENT OPERATORS
       set<Key, Compare, Allocator>&
       operator=(const set<Key, Compare, Allocator>& x);

   Returns a reference to self. Self shares an implementation with x.

ALLOCATORS
       allocator_type
       get_allocator() const;

   Returns a copy of the allocator used by self for storage management.

ITERATORS
       iterator
       begin();

   Returns an iterator that points to the first element in self.

const_iterator
begin() const;

   Returns a const_iterator that points to the first element in self.

iterator
end();

   Returns an iterator that points to the past-the-end value.

const_iterator
end() const;

   Returns a const_iterator that points to the past-the-end value.

reverse_iterator
rbegin();

   Returns a reverse_iterator that points to the past-the-end value.

const_reverse_iterator
rbegin() const;

   Returns a const_reverse_iterator that points to the past-the-end value.

reverse_iterator
rend();

   Returns a reverse_iterator that points to the first element.

const_reverse_iterator
rend() const;

   Returns a const_reverse_iterator that points to the first element.

MEMBER FUNCTIONS
       void
       clear();

   Erases all elements from the set.

size_type
count(const key_type& x) const;

   Returns the number of elements equal to x.  Since  a	 set  supports	unique
   keys, count always returns 1 or 0.

bool
empty() const;

   Returns true if the size is zero.

pair<;iterator, iterator>
equal_range(const key_type&  x) const;

   Returns pair(lower_bound(x),upper_bound(x)). The equal_range function indi‐
   cates the valid range for insertion of x into the set.

size_type
erase(const key_type& x);

   Deletes all the elements matching  x.    Returns  the  number  of  elements
   erased. Since a set supports unique keys, erase always returns 1 or 0.

void
erase(iterator position);

   Deletes  the	 map  element  pointed to by the iterator position. Returns an
   iterator pointing to the element following the deleted element, or end() if
   the deleted item was the last one in this list.

void
erase(iterator first, iterator last);

   Deletes the elements in the range (first, last). Returns an iterator point‐
   ing to the element following the last deleted element, or  end()  if	 there
   were no elements after the deleted range.

iterator
find(const key_value& x) const;

   Returns  an	iterator that points to the element equal to x. If there is no
   such element, the iterator points to the past-the-end value.

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

   Inserts x into self according to the comparison function object.  The  tem‐
   plate's  default  comparison	 function object is less (<). If the insertion
   succeeds, it returns a pair composed of the	iterator  position  where  the
   insertion  took  place and true. Otherwise, the pair contains the end value
   and false.

iterator
insert(iterator position, const value_type& x);

   x is inserted into the set. A position may be supplied as a hint  regarding
   where  to  do the insertion. If the insertion is done right after position,
   then it takes amortized constant time. Otherwise it takes 0 (log  N)	 time.
   The return value points to the inserted x.

template <;class InputIterator>
void
insert(InputIterator first, InputIterator last);

   Inserts copies of the elements in the range [first, last].

key_compare
key_comp() const;

   Returns the comparison function object for the set.

iterator
lower_bound(const key_type& x) const;

   Returns  an	iterator that points to the first element that is greater than
   or equal to x. If there is no such element,	the  iterator  points  to  the
   past-the-end value.

size_type
max_size() const;

   Returns the size of the largest possible set.

size_type
size() const;

   Returns the number of elements.

void
swap(set<;Key, Compare, Allocator>& x);

   Exchanges self with x.

iterator
upper_bound(const key_type& x) const

   Returns  an	iterator that points to the first element that is greater than
   or equal to x. If there is no such element,	the  iterator  points  to  the
   past-the-end value.

value_compare
value_comp() const;

   Returns  the	 set's	comparison  object.  This is identical to the function
   key_comp().

NON-MEMBER OPERATORS
       template <class Key, class Compare, class Allocator>
       bool operator==(const set<Key, Compare, Allocator>& x,
       const set<Key, Compare, Allocator>& y);

   Returns true if x is the same as y.

template <;class Key, class Compare, class Allocator>
bool operator!=(const set<Key, Compare, Allocator>& x,
const set<;Key, Compare, Allocator>& y);

   Returns !(x==y).

template <;class Key, class Compare, class Allocator>
bool operator<;(const set <Key, Compare, Allocator>& x,
const set <;Key, Compare, Allocator>& y);

   Returns true if the elements contained in x are lexicographically less than
   the elements contained in y.

template <;class Key, class Compare, class Allocator>
bool operator>(const set <Key, Compare, Allocator>& x,
const set <;Key, Compare, Allocator>& y);

   Returns y < x.

template <;class Key, class Compare, class Allocator>
bool operator<;=(const set <Key, Compare, Allocator>& x,
const set <;Key, Compare, Allocator>& y);

   Returns !(y < x).

template <;class Key, class Compare, class Allocator>
bool operator>=(const set <Key, Compare, Allocator>& x,
const set <;Key, Compare, Allocator>& y);

   Returns !(x < y).

SPECIALIZED ALGORITHMS
       template <class Key, class Compare, class Allocator>
       void swap(set <Key, Compare, Allocator>& a,
       set <Key, Compare, Allocator>& b);

   Swaps the contents of a and b.

EXAMPLE
       //
       // setex.cpp
       //
       #include <set>
       #include <iostream>
       using namespace std;

       typedef set<double, less<double>, allocator<double> >
       set_type;
ostream& operator<;<(ostream& out, const set_type& s)
 {
copy(s.begin(), s.end(),
    ostream_iterator<set_type::value_type,char>(cout," "));
return out;
 }

int main(void)
 {
// create a set of doubles
  set_type   sd;
  int	      i;

for(i = 0; i < 10; ++i) {
// insert values
sd.insert(i);
   }

// print out the set
cout <;< sd << endl << endl;

// now let's erase half of the elements in the set
int half = sd.size() >> 1;
set_type::iterator sdi = sd.begin();
advance(sdi,half);
sd.erase(sd.begin(),sdi);
// print it out again
cout <;< sd << endl << endl;

// Make another set and an empty result set
set_type sd2, sdResult;
for (i = 1; i < 9; i++)
 sd2.insert(i+5);
cout <;< sd2 << endl;
// Try a couple of set algorithms
set_union(sd.begin(),sd.end(),sd2.begin(),sd2.end(),
	 inserter(sdResult,sdResult.begin()));
cout <;< "Union:" << endl << sdResult << endl;
sdResult.erase(sdResult.begin(),sdResult.end());
set_intersection(sd.begin(),sd.end(),
		sd2.begin(),sd2.end(),
		inserter(sdResult,sdResult.begin()));
cout <;< "Intersection:" << endl << sdResult << endl;
return 0;
 }

Program Output

0 1 2 3 4 5 6 7 8 9

5 6 7 8 9

6 7 8 9 10 11 12 13
Union:
5 6 7 8 9 10 11 12 13
Intersection:
6 7 8 9

WARNINGS
       Member  function	 templates  are used in all containers included in the
       Standard Template Library. An example of this feature is the  construc‐
       tor for set <Key, Compare, Allocator> that takes two templatized itera‐
       tors:

       template <class InputIterator>
       set (InputIterator, InputIterator,
       const Compare& = Compare(),
       const Allocator& = Allocator());

       set also has an insert function of this type. These functions, when not
       restricted  by compiler limitations, allow you to use any type of input
       iterator as arguments.	For compilers that do not  support  this  fea‐
       ture,  substitute  functions allow you to use an iterator obtained from
       the same type of container as the one you are constructing (or  calling
       a  member function on), or you can use a pointer to the type of element
       you have in the container.

       For example, if your compiler does not  support	member	function  tem‐
       plates, you can construct a set in the following two ways:

       int intarray[10];
       set<int> first_set(intarray, intarray + 10);
       set<int> second_set(first_set.begin(),
       first_set.end());

       but not this way:

       set<long> long_set(first_set.begin(),
       first_set.end());

       since the long_set and first_set are not the same type.

       Also, many compilers do not support default template arguments. If your
       compiler is one of these you always need to supply the Compare template
       argument and the Allocator template argument. For instance, you need to
       write:

       set<int, less<int>, allocator<int> >

       instead of:

       set<int>

       If your compiler does not support namespaces, then you do not need  the
       using declaration for std.

SEE ALSO
       allocator, Bidirectional_Iterators, Containers, lexicographical_compare

Rogue Wave Software		  02 Apr 1998			     set(3C++)

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