etl/docs/containers/sets/multiset.md
John Wellbelove 4a88884b39
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---------

Co-authored-by: Roland Reichwein <Roland.Reichwein@bmw.de>
Co-authored-by: John Wellbelove <john.wellbelove@etlcpp.com>
Co-authored-by: John Wellbelove <john.wellbelove@etlcpp.co.uk>
2026-06-06 13:12:44 +01:00

7.7 KiB

title
multiset

{{< callout type="info">}} Header: multiset.h
Similar to: std::multiset {{< /callout >}}

A fixed capacity multiset.
Uses etl or std::less as the default key comparison method.

etl::multiset<typename T, const size_t SIZE, TKeyCompare = etl::less>

Inherits from etl::iset<T, TKeyCompare>.
etl::iset may be used as a size independent pointer or reference type for any etl::multiset instance.

Template deduction guides

C++17 and above

template <typename... TPairs>
etl::multiset(TPairs...)

Example

etl::multiset data{ 0, 1, 2, 3, 4, 5, 6, 7 };

Defines data as an multiset of int, of length 8, containing the supplied data.

Make template

C++11 and above

template <typename TKey, 
          typename TKeyCompare = etl::less<TKey>, 
          typename... TPairs>
constexpr auto make_set(TValues&&... values)

Example

auto data = etl::make_set<int>(0, 1, 2, 3, 4, 5, 6, 7);

Member types

value_type              T
size_type               size_t
difference_type         ptrdiff_t
reference               value_type&
const_reference         const value_type&
pointer                 value_type*
const_pointer           const value_type*
iterator                Random access iterator
const_iterator          Constant random access iterator
reverse_iterator        ETL_OR_STD::reverse_iterator<iterator>
const_reverse_iterator  ETL_OR_STD::reverse_iterator<const_iterator>

Constructors

etl::multiset<T, SIZE, TKeyCompare>()

Description


template <typename TIterator>
etl::multiset<T, SIZE, TKeyCompare>(TIterator begin, TIterator end)

Description
If the map is full then emits an etl::reference_flat_set_full.
If asserts or exceptions are not enabled then undefined behaviour occurs.

Element access

iterator find(const value_type& v)
const_iterator find(const value_type& v) const

Description
Searches the container for an element with a value of v and returns an iterator to it if found, otherwise it returns an iterator to etl::multiset::end().


size_type count(const value_type& v) const

Description
Count elements with a specific key. Searches the container for elements with a value of v and returns the number of matches


iterator lower_bound(const value_type& v)
const_iterator lower_bound(const value_type& v) const

Description
Searches for an element with the key not less than v.
Returns an iterator to the element, or end() if not found.


iterator upper_bound(const value_type& v)
const_iterator upper_bound (const value_type& v) const

Description
Searches for an element with the key greater than v.
Returns an iterator to the element, or end() if not found.


pair<const_iterator, const_iterator> equal_range(const value_type& v) const
pair<iterator, iterator> equal_range(const value_type& v)

Description
Returns the range of elements with a key equal to v. The return type is either std::pair (default) or etl::pair (ETL_NO_STL)


For comparators that define is_transparent.

template <typename K>
iterator find(const K& key)

Description
Since: 20.21.0
C++11 or above.


template <typename K>
const_iterator find(const K& key) const

Description
Since: 20.21.0
C++11 or above.


template <typename K>
iterator lower_bound(const K& key)

Description
Searches for an element with the key not less than key.
Returns an iterator to the element, or end() if not found. Since: 20.21.0
C++11 or above.


template <typename K>
const_iterator lower_bound(const K& key) const

Description
Searches for an element with the key not less than key.
Returns a const iterator to the element, or end() if not found. Since: 20.21.0
C++11 or above.


template <typename K>
iterator upper_bound(const K& key)

Description
Searches for an element with the key greater than key.
Returns an iterator to the element, or end() if not found. Since: 20.21.0
C++11 or above.


template <typename K>
const_iterator upper_bound(const K& key) const

Description
Searches for an element with the key greater than key.
Returns a const iterator to the element, or end() if not found. Since: 20.21.0
C++11 or above.


template <typename K>
pair<iterator, iterator> equal_range(const K& key)

Description
Returns the range of elements with a key equal to key. The return type is either std::pair (default) or etl::pair (ETL_NO_STL) Since: 20.21.0
C++11 or above.


template <typename K>
pair<const_iterator, const_iterator> equal_range(const K& key) const

Description
Returns the range of elements with a key equal to key. The return type is either std::pair (default) or etl::pair (ETL_NO_STL) Since: 20.21.0
C++11 or above.


bool contains(key_value_parameter_t key) const

Description
Check if the container contains the key. Since: 20.21.0


For comparators that define is_transparent.

template <typename K>

Description
Since: 20.21.0
C++11 or above.


bool contains(const K& k) const

Check if the container contains the key. Since: 20.21.0
C++11 or above.

Iterators

iterator begin()
const_iterator begin() const
const_iterator cbegin() const

Description
Returns an iterator to the beginning of the map.


iterator end()
const_iterator end() const
const_iterator cend() const

Description
Returns an iterator to the end of the map.


iterator rbegin()
const_iterator rbegin() const
const_iterator crbegin() const

Description
Returns a reverse iterator to the beginning of the map.


iterator rbegin()
const_iterator rbegin() const
const_iterator crbegin() const

Description
Returns a reverse iterator to the beginning of the map.

Capacity

bool empty() const

Description
Returns true if the size of the map is zero, otherwise false.


bool full() const

Description
Returns true if the size of the map is SIZE, otherwise false.


size_t size() const

Description
Returns the size of the map.


size_t max_size() const

Description
Returns the maximum possible size of the map.


size_t available() const

Description
Returns the remaining available capacity in the map.

Modifiers

<=20.19.0

template <typename TIterator>
void insert(TIterator begin, TIterator end)

Description


=20.20.0

template <typename TIterator>
iterator insert(TIterator begin, TIterator end)

Description


iterator insert(parameter_t value)

Description
Inserts values in to the map. If the multiset is full then emits an etl::multiset_full.
If asserts or exceptions are not enabled then undefined behaviour occurs.


template <typename TIterator>
iterator erase(TIterator begin, TIterator end)

Description


iterator erase(TIterator element)

Description
Erases values in the multiset. Iterators are not checked for validity.


size_t erase(const key_type& key)

Description


20.21.0

template <typename K>
size_t erase(K&& key)

Description


void clear()

Description
Clears the map to a size of zero.

Non-member functions

operator ==

Description
true if the contents of the sets are equal, otherwise false.


operator !=

Description
true if the contents of the sets are not equal, otherwise false.