std::multiset<Key,Compare,Allocator>::multiset
(1) | ||
multiset(); |
(until C++11) | |
multiset() : multiset(Compare()) {} |
(since C++11) | |
explicit multiset( const Compare& comp, const Allocator& alloc = Allocator() ); |
(2) | |
explicit multiset( const Allocator& alloc ); |
(3) | (since C++11) |
template< class InputIt > multiset( InputIt first, InputIt last, |
(4) | |
template< class InputIt > multiset( InputIt first, InputIt last, |
(5) | (since C++14) |
multiset( const multiset& other ); |
(6) | |
multiset( const multiset& other, const Allocator& alloc ); |
(7) | (since C++11) |
multiset( multiset&& other ); |
(8) | (since C++11) |
multiset( multiset&& other, const Allocator& alloc ); |
(9) | (since C++11) |
multiset( std::initializer_list<value_type> init, const Compare& comp = Compare(), |
(10) | (since C++11) |
multiset( std::initializer_list<value_type> init, const Allocator& alloc ) |
(11) | (since C++14) |
template< container-compatible-range<value_type> R > multiset( std::from_range_t, R&& rg, |
(12) | (since C++23) |
template< container-compatible-range<value_type> R > multiset( std::from_range_t, R&& rg, |
(13) | (since C++23) |
Constructs new container from a variety of data sources and optionally using user supplied allocator alloc or comparison function object comp.
[
first,
last)
. [
first,
last)
is not a valid range, the behavior is undefined.
If alloc is not provided, allocator is obtained by calling std::allocator_traits<allocator_type>:: |
(since C++11) |
During class template argument deduction, only the first argument contributes to the deduction of the container's |
(since C++23) |
During class template argument deduction, only the first argument contributes to the deduction of the container's |
(since C++23) |
Contents |
[edit] Parameters
alloc | - | allocator to use for all memory allocations of this container |
comp | - | comparison function object to use for all comparisons of keys |
first, last | - | the range to copy the elements from |
other | - | another container to be used as source to initialize the elements of the container with |
init | - | initializer list to initialize the elements of the container with |
rg | - | a container compatible range, that is, an input_range whose elements are convertible to value_type
|
Type requirements | ||
-InputIt must meet the requirements of LegacyInputIterator.
| ||
-Compare must meet the requirements of Compare.
| ||
-Allocator must meet the requirements of Allocator.
|
[edit] Complexity
[
first,
last)
is already sorted by value_comp().[edit] Exceptions
Calls to Allocator::allocate
may throw.
[edit] Notes
After container move construction (overload (8,9)), references, pointers, and iterators (other than the end iterator) to other
remain valid, but refer to elements that are now in *this. The current standard makes this guarantee via the blanket statement in [container.reqmts]/67, and a more direct guarantee is under consideration via LWG issue 2321.
Although not formally required until C++23, some implementations has already put the template parameter Allocator
into non-deduced contexts in earlier modes.
Feature-test macro | Value | Std | Feature |
---|---|---|---|
__cpp_lib_containers_ranges |
202202L |
(C++23) | Ranges-aware construction and insertion; overloads (12,13) |
[edit] Example
#include <iostream> #include <set> #include <string_view> template <typename T> void println(const std::string_view name, const std::multiset<T>& ms) { std::cout << name << ": "; for (const auto& element : ms) std::cout << element << ' '; std::cout << '\n'; } int main() { // (1) Default constructor std::multiset<int> a; a.insert(4); a.insert(3); a.insert(2); a.insert(1); println("a", a); // (4) Range constructor std::multiset<int> b(a.begin(), a.find(3)); println("b", b); // (6) Copy constructor std::multiset<int> c(a); println("c", c); // (8) Move constructor std::multiset<int> d(std::move(a)); println("d", d); // (10) Initializer list constructor std::multiset<int> e{3, 2, 1, 2, 4, 7, 3}; println("e", e); // (12) Range constructor const auto w = {"α", "β", "γ", "δ", "δ", "γ", "β", "α"}; #if __cpp_lib_containers_ranges std::multiset<std::string> f(std::from_range, w); // overload (12) #else std::multiset<std::string> f(w.begin(), w.end()); // fallback to (4) #endif println("f", f); }
Output:
a: 1 2 3 4 b: 1 2 c: 1 2 3 4 d: 1 2 3 4 e: 1 2 2 3 3 4 7 f: α α β β γ γ δ δ
[edit] Defect reports
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
DR | Applied to | Behavior as published | Correct behavior |
---|---|---|---|
LWG 2076 | C++11 | overload (4) conditionally required Key to be CopyInsertable into *this
|
not required |
LWG 2193 | C++11 | the default constructor was explicit | made non-explicit |
[edit] See also
assigns values to the container (public member function) |