std::set - Man Page

using insert_return_type
using node_type

typedef _Key key_type
Public typedefs.
typedef _Key value_type
Public typedefs.
typedef _Compare key_compare
Public typedefs.
typedef _Compare value_compare
Public typedefs.
typedef _Alloc allocator_type
Public typedefs.

typedef _Alloc_traits::pointer pointer
Iterator-related typedefs.
typedef _Alloc_traits::const_pointer const_pointer
Iterator-related typedefs.
typedef _Alloc_traits::reference reference
Iterator-related typedefs.
typedef _Alloc_traits::const_reference const_reference
Iterator-related typedefs.
typedef _Rep_type::const_iterator iterator
Iterator-related typedefs.
typedef _Rep_type::const_iterator const_iterator
Iterator-related typedefs.
typedef _Rep_type::const_reverse_iterator reverse_iterator
Iterator-related typedefs.
typedef _Rep_type::const_reverse_iterator const_reverse_iterator
Iterator-related typedefs.
typedef _Rep_type::size_type size_type
Iterator-related typedefs.
typedef _Rep_type::difference_type difference_type
Iterator-related typedefs.

set ()=default
Default constructor creates no elements.
template<typename _InputIterator > set (_InputIterator __first, _InputIterator __last)
Builds a set from a range.
template<typename _InputIterator > set (_InputIterator __first, _InputIterator __last, const _Compare &__comp, const allocator_type &__a=allocator_type())
Builds a set from a range.
template<typename _InputIterator > set (_InputIterator __first, _InputIterator __last, const allocator_type &__a)
Allocator-extended range constructor.
set (const _Compare &__comp, const allocator_type &__a=allocator_type())
Creates a set with no elements.
set (const allocator_type &__a)
Allocator-extended default constructor.
set (const set &)=default
Set copy constructor.
set (const set &__x, const __type_identity_t< allocator_type > &__a)
Allocator-extended copy constructor.
set (initializer_list< value_type > __l, const _Compare &__comp=_Compare(), const allocator_type &__a=allocator_type())
Builds a set from an initializer_list.
set (initializer_list< value_type > __l, const allocator_type &__a)
Allocator-extended initialier-list constructor.
set (set &&)=default
Set move constructor
set (set &&__x, const __type_identity_t< allocator_type > &__a) noexcept(is_nothrow_copy_constructible< _Compare >::value &&_Alloc_traits::_S_always_equal())
Allocator-extended move constructor.
~set ()=default
iterator begin () const noexcept
iterator cbegin () const noexcept
iterator cend () const noexcept
void clear () noexcept
reverse_iterator crbegin () const noexcept
reverse_iterator crend () const noexcept
template<typename... _Args> std::pair< iterator, bool > emplace (_Args &&... __args)
Attempts to build and insert an element into the set.
template<typename... _Args> iterator emplace_hint (const_iterator __pos, _Args &&... __args)
Attempts to insert an element into the set.
bool empty () const noexcept
Returns true if the set is empty.
iterator end () const noexcept
size_type erase (const key_type &__x)
Erases elements according to the provided key.
_GLIBCXX_ABI_TAG_CXX11 iterator erase (const_iterator __first, const_iterator __last)
Erases a [__first,__last) range of elements from a set.
_GLIBCXX_ABI_TAG_CXX11 iterator erase (const_iterator __position)
Erases an element from a set.
node_type extract (const key_type &__x)
Extract a node.
node_type extract (const_iterator __pos)
Extract a node.
allocator_type get_allocator () const noexcept
Returns the allocator object with which the set was constructed.
template<typename _InputIterator > void insert (_InputIterator __first, _InputIterator __last)
A template function that attempts to insert a range of elements.
std::pair< iterator, bool > insert (const value_type &__x)
Attempts to insert an element into the set.
iterator insert (const_iterator __hint, node_type &&__nh)
Re-insert an extracted node.
iterator insert (const_iterator __position, const value_type &__x)
Attempts to insert an element into the set.
iterator insert (const_iterator __position, value_type &&__x)
void insert (initializer_list< value_type > __l)
Attempts to insert a list of elements into the set.
insert_return_type insert (node_type &&__nh)
Re-insert an extracted node.
std::pair< iterator, bool > insert (value_type &&__x)
key_compare key_comp () const
Returns the comparison object with which the set was constructed.
size_type max_size () const noexcept
Returns the maximum size of the set.
template<typename _Compare1 > void merge (multiset< _Key, _Compare1, _Alloc > &&__source)
template<typename _Compare1 > void merge (multiset< _Key, _Compare1, _Alloc > &__source)
template<typename _Compare1 > void merge (set< _Key, _Compare1, _Alloc > &&__source)
template<typename _Compare1 > void merge (set< _Key, _Compare1, _Alloc > &__source)
set & operator= (const set &)=default
Set assignment operator.
set & operator= (initializer_list< value_type > __l)
Set list assignment operator.
set & operator= (set &&)=default
Move assignment operator.
reverse_iterator rbegin () const noexcept
reverse_iterator rend () const noexcept
size_type size () const noexcept
Returns the size of the set.
void swap (set &__x) noexcept(/*conditional */)
Swaps data with another set.
value_compare value_comp () const
Returns the comparison object with which the set was constructed.

size_type count (const key_type &__x) const
Finds the number of elements.
template<typename _Kt > auto count (const _Kt &__x) const -> decltype(_M_t._M_count_tr(__x))
Finds the number of elements.

bool contains (const key_type &__x) const
Finds whether an element with the given key exists.
template<typename _Kt > auto contains (const _Kt &__x) const -> decltype(_M_t._M_find_tr(__x), void(), true)
Finds whether an element with the given key exists.

iterator find (const key_type &__x)
Tries to locate an element in a set.
const_iterator find (const key_type &__x) const
Tries to locate an element in a set.
template<typename _Kt > auto find (const _Kt &__x) -> decltype(iterator{_M_t._M_find_tr(__x)})
Tries to locate an element in a set.
template<typename _Kt > auto find (const _Kt &__x) const -> decltype(const_iterator{_M_t._M_find_tr(__x)})
Tries to locate an element in a set.

iterator lower_bound (const key_type &__x)
Finds the beginning of a subsequence matching given key.
const_iterator lower_bound (const key_type &__x) const
Finds the beginning of a subsequence matching given key.
template<typename _Kt > auto lower_bound (const _Kt &__x) -> decltype(iterator(_M_t._M_lower_bound_tr(__x)))
Finds the beginning of a subsequence matching given key.
template<typename _Kt > auto lower_bound (const _Kt &__x) const -> decltype(const_iterator(_M_t._M_lower_bound_tr(__x)))
Finds the beginning of a subsequence matching given key.

iterator upper_bound (const key_type &__x)
Finds the end of a subsequence matching given key.
const_iterator upper_bound (const key_type &__x) const
Finds the end of a subsequence matching given key.
template<typename _Kt > auto upper_bound (const _Kt &__x) -> decltype(iterator(_M_t._M_upper_bound_tr(__x)))
Finds the end of a subsequence matching given key.
template<typename _Kt > auto upper_bound (const _Kt &__x) const -> decltype(iterator(_M_t._M_upper_bound_tr(__x)))
Finds the end of a subsequence matching given key.

std::pair< iterator, iterator > equal_range (const key_type &__x)
Finds a subsequence matching given key.
std::pair< const_iterator, const_iterator > equal_range (const key_type &__x) const
Finds a subsequence matching given key.
template<typename _Kt > auto equal_range (const _Kt &__x) -> decltype(pair< iterator, iterator >(_M_t._M_equal_range_tr(__x)))
Finds a subsequence matching given key.
template<typename _Kt > auto equal_range (const _Kt &__x) const -> decltype(pair< iterator, iterator >(_M_t._M_equal_range_tr(__x)))
Finds a subsequence matching given key.

template<typename _K1 , typename _C1 , typename _A1 > bool operator< (const set< _K1, _C1, _A1 > &, const set< _K1, _C1, _A1 > &)
template<typename _K1 , typename _C1 , typename _A1 > bool operator== (const set< _K1, _C1, _A1 > &, const set< _K1, _C1, _A1 > &)
template<typename , typename > struct std::_Rb_tree_merge_helper

class std::set< _Key, _Compare, _Alloc >"A standard container made up of unique keys, which can be retrieved in logarithmic time.

Since

C++98

Template Parameters

Meets the requirements of a container, a reversible container, and an associative container (using unique keys).

Sets support bidirectional iterators.

The private tree data is declared exactly the same way for set and multiset; the distinction is made entirely in how the tree functions are called (*_unique versus *_equal, same as the standard).

Public typedefs.

Iterator-related typedefs.

Iterator-related typedefs.

Iterator-related typedefs.

Iterator-related typedefs.

Iterator-related typedefs.

Iterator-related typedefs.

Public typedefs.

Public typedefs.

Iterator-related typedefs.

Iterator-related typedefs.

Iterator-related typedefs.

Iterator-related typedefs.

Public typedefs.

Public typedefs.

Default constructor creates no elements.

Creates a set with no elements.

Parameters

Builds a set from a range.

Parameters

Create a set consisting of copies of the elements from [__first,__last). This is linear in N if the range is already sorted, and NlogN otherwise (where N is distance(__first,__last)).

Builds a set from a range.

Parameters

Create a set consisting of copies of the elements from [__first,__last). This is linear in N if the range is already sorted, and NlogN otherwise (where N is distance(__first,__last)).

Set copy constructor. Whether the allocator is copied depends on the allocator traits.

Set move constructor The newly-created set contains the exact contents of the moved instance. The moved instance is a valid, but unspecified, set.

Builds a set from an initializer_list.

Parameters

Create a set consisting of copies of the elements in the list. This is linear in N if the list is already sorted, and NlogN otherwise (where N is __l.size()).

Allocator-extended default constructor.

Allocator-extended copy constructor.

Allocator-extended move constructor.

Allocator-extended initialier-list constructor.

Allocator-extended range constructor.

The dtor only erases the elements, and note that if the elements themselves are pointers, the pointed-to memory is not touched in any way. Managing the pointer is the user's responsibility.

Returns a read-only (constant) iterator that points to the first element in the set. Iteration is done in ascending order according to the keys.

Returns a read-only (constant) iterator that points to the first element in the set. Iteration is done in ascending order according to the keys.

Returns a read-only (constant) iterator that points one past the last element in the set. Iteration is done in ascending order according to the keys.

Erases all elements in a set. Note that this function only erases the elements, and that if the elements themselves are pointers, the pointed-to memory is not touched in any way. Managing the pointer is the user's responsibility.

[inline]"

Finds whether an element with the given key exists.

Parameters

Returns

True if there is an element with the specified key.

Finds whether an element with the given key exists.

Parameters

Returns

True if there is an element with the specified key.

[inline]"

Finds the number of elements.

Parameters

Returns

Number of elements with specified key.

This function only makes sense for multisets; for set the result will either be 0 (not present) or 1 (present).

Finds the number of elements.

Parameters

Returns

Number of elements with specified key.

This function only makes sense for multisets; for set the result will either be 0 (not present) or 1 (present).

Returns a read-only (constant) iterator that points to the last element in the set. Iteration is done in descending order according to the keys.

Returns a read-only (constant) reverse iterator that points to the last pair in the set. Iteration is done in descending order according to the keys.

Attempts to build and insert an element into the set.

Parameters

Returns

A pair, of which the first element is an iterator that points to the possibly inserted element, and the second is a bool that is true if the element was actually inserted.

This function attempts to build and insert an element into the set. A set relies on unique keys and thus an element is only inserted if it is not already present in the set.

Insertion requires logarithmic time.

References std::forward().

Attempts to insert an element into the set.

Parameters

Returns

An iterator that points to the element with key equivalent to the one generated from __args (may or may not be the element itself).

This function is not concerned about whether the insertion took place, and thus does not return a boolean like the single-argument emplace() does. Note that the first parameter is only a hint and can potentially improve the performance of the insertion process. A bad hint would cause no gains in efficiency.

For more on hinting, see: https://gcc.gnu.org/onlinedocs/libstdc++/manual/associative.html#containers.associative.insert_hints

Insertion requires logarithmic time (if the hint is not taken).

References std::forward().

Returns true if the set is empty.

Returns a read-only (constant) iterator that points one past the last element in the set. Iteration is done in ascending order according to the keys.

Referenced by std::set< _Key, _Compare, _Alloc >::extract().

[inline]"

Finds a subsequence matching given key.

Parameters

Returns

Pair of iterators that possibly points to the subsequence matching given key.

This function is equivalent to

std::make_pair(c.lower_bound(val),
               c.upper_bound(val))

(but is faster than making the calls separately).

This function probably only makes sense for multisets.

[inline]"

Finds a subsequence matching given key.

Parameters

Returns

Pair of iterators that possibly points to the subsequence matching given key.

This function is equivalent to

std::make_pair(c.lower_bound(val),
               c.upper_bound(val))

(but is faster than making the calls separately).

This function probably only makes sense for multisets.

Finds a subsequence matching given key.

Parameters

Returns

Pair of iterators that possibly points to the subsequence matching given key.

This function is equivalent to

std::make_pair(c.lower_bound(val),
               c.upper_bound(val))

(but is faster than making the calls separately).

This function probably only makes sense for multisets.

Finds a subsequence matching given key.

Parameters

Returns

Pair of iterators that possibly points to the subsequence matching given key.

This function is equivalent to

std::make_pair(c.lower_bound(val),
               c.upper_bound(val))

(but is faster than making the calls separately).

This function probably only makes sense for multisets.

Erases elements according to the provided key.

Parameters

Returns

The number of elements erased.

This function erases all the elements located by the given key from a set. Note that this function only erases the element, and that if the element is itself a pointer, the pointed-to memory is not touched in any way. Managing the pointer is the user's responsibility.

Erases a [__first,__last) range of elements from a set.

Parameters

Returns

The iterator __last.

This function erases a sequence of elements from a set. Note that this function only erases the element, and that if the element is itself a pointer, the pointed-to memory is not touched in any way. Managing the pointer is the user's responsibility.

Erases an element from a set.

Parameters

Returns

An iterator pointing to the element immediately following __position prior to the element being erased. If no such element exists, end() is returned.

This function erases an element, pointed to by the given iterator, from a set. Note that this function only erases the element, and that if the element is itself a pointer, the pointed-to memory is not touched in any way. Managing the pointer is the user's responsibility.

Extract a node.

Extract a node.

References std::set< _Key, _Compare, _Alloc >::end().

[inline]"

Tries to locate an element in a set.

Parameters

Returns

Iterator pointing to sought-after element, or end() if not found.

This function takes a key and tries to locate the element with which the key matches. If successful the function returns an iterator pointing to the sought after element. If unsuccessful it returns the past-the-end ( end() ) iterator.

[inline]"

Tries to locate an element in a set.

Parameters

Returns

Iterator pointing to sought-after element, or end() if not found.

This function takes a key and tries to locate the element with which the key matches. If successful the function returns an iterator pointing to the sought after element. If unsuccessful it returns the past-the-end ( end() ) iterator.

Tries to locate an element in a set.

Parameters

Returns

Iterator pointing to sought-after element, or end() if not found.

This function takes a key and tries to locate the element with which the key matches. If successful the function returns an iterator pointing to the sought after element. If unsuccessful it returns the past-the-end ( end() ) iterator.

Tries to locate an element in a set.

Parameters

Returns

Iterator pointing to sought-after element, or end() if not found.

This function takes a key and tries to locate the element with which the key matches. If successful the function returns an iterator pointing to the sought after element. If unsuccessful it returns the past-the-end ( end() ) iterator.

Returns the allocator object with which the set was constructed.

A template function that attempts to insert a range of elements.

Parameters

Complexity similar to that of the range constructor.

Attempts to insert an element into the set.

Parameters

Returns

A pair, of which the first element is an iterator that points to the possibly inserted element, and the second is a bool that is true if the element was actually inserted.

This function attempts to insert an element into the set. A set relies on unique keys and thus an element is only inserted if it is not already present in the set.

Insertion requires logarithmic time.

References std::pair< _T1, _T2 >::first, and std::pair< _T1, _T2 >::second.

Referenced by std::set< _Key, _Compare, _Alloc >::insert().

Re-insert an extracted node.

References std::move().

Attempts to insert an element into the set.

Parameters

Returns

An iterator that points to the element with key of __x (may or may not be the element passed in).

This function is not concerned about whether the insertion took place, and thus does not return a boolean like the single-argument insert() does. Note that the first parameter is only a hint and can potentially improve the performance of the insertion process. A bad hint would cause no gains in efficiency.

For more on hinting, see: https://gcc.gnu.org/onlinedocs/libstdc++/manual/associative.html#containers.associative.insert_hints

Insertion requires logarithmic time (if the hint is not taken).

Attempts to insert a list of elements into the set.

Parameters

Complexity similar to that of the range constructor.

References std::set< _Key, _Compare, _Alloc >::insert().

Re-insert an extracted node.

References std::move().

Returns the comparison object with which the set was constructed.

[inline]"

Finds the beginning of a subsequence matching given key.

Parameters

Returns

Iterator pointing to first element equal to or greater than key, or end().

This function returns the first element of a subsequence of elements that matches the given key. If unsuccessful it returns an iterator pointing to the first element that has a greater value than given key or end() if no such element exists.

[inline]"

Finds the beginning of a subsequence matching given key.

Parameters

Returns

Iterator pointing to first element equal to or greater than key, or end().

This function returns the first element of a subsequence of elements that matches the given key. If unsuccessful it returns an iterator pointing to the first element that has a greater value than given key or end() if no such element exists.

Finds the beginning of a subsequence matching given key.

Parameters

Returns

Iterator pointing to first element equal to or greater than key, or end().

This function returns the first element of a subsequence of elements that matches the given key. If unsuccessful it returns an iterator pointing to the first element that has a greater value than given key or end() if no such element exists.

Finds the beginning of a subsequence matching given key.

Parameters

Returns

Iterator pointing to first element equal to or greater than key, or end().

This function returns the first element of a subsequence of elements that matches the given key. If unsuccessful it returns an iterator pointing to the first element that has a greater value than given key or end() if no such element exists.

Returns the maximum size of the set.

Set assignment operator. Whether the allocator is copied depends on the allocator traits.

Set list assignment operator.

Parameters

This function fills a set with copies of the elements in the initializer list __l.

Note that the assignment completely changes the set and that the resulting set's size is the same as the number of elements assigned.

Move assignment operator.

Returns a read-only (constant) iterator that points to the last element in the set. Iteration is done in descending order according to the keys.

Returns a read-only (constant) reverse iterator that points to the last pair in the set. Iteration is done in descending order according to the keys.

Returns the size of the set.

Swaps data with another set.

Parameters

This exchanges the elements between two sets in constant time. (It is only swapping a pointer, an integer, and an instance of the Compare type (which itself is often stateless and empty), so it should be quite fast.) Note that the global std::swap() function is specialized such that std::swap(s1,s2) will feed to this function.

Whether the allocators are swapped depends on the allocator traits.

[inline]"

Finds the end of a subsequence matching given key.

Parameters

Returns

Iterator pointing to the first element greater than key, or end().

[inline]"

Finds the end of a subsequence matching given key.

Parameters

Returns

Iterator pointing to the first element greater than key, or end().

Finds the end of a subsequence matching given key.

Parameters

Returns

Iterator pointing to the first element greater than key, or end().

Finds the end of a subsequence matching given key.

Parameters

Returns

Iterator pointing to the first element greater than key, or end().

Returns the comparison object with which the set was constructed.