(1) | ||
set(); | (until C++11) | |
set() : set(Compare()) { } | (since C++11) | |
explicit set( const Compare& comp, const Allocator& alloc = Allocator() ); | (2) | |
explicit set( const Allocator& alloc ); | (3) | (since C++11) |
template< class InputIt > set( InputIt first, InputIt last, const Compare& comp = Compare(), const Allocator& alloc = Allocator() ); | (4) | |
template< class InputIt > set( InputIt first, InputIt last, const Allocator& alloc ) : set(first, last, Compare(), alloc) { } | (5) | (since C++14) |
set( const set& other ); | (6) | |
set( const set& other, const Allocator& alloc ); | (7) | (since C++11) |
set( set&& other ); | (8) | (since C++11) |
set( set&& other, const Allocator& alloc ); | (9) | (since C++11) |
set( std::initializer_list<value_type> init, const Compare& comp = Compare(), const Allocator& alloc = Allocator() ); | (10) | (since C++11) |
set( std::initializer_list<value_type> init, const Allocator& alloc ) : set(init, Compare(), alloc) { } | (11) | (since C++14) |
template< container-compatible-range<value_type> R > set( std::from_range_t, R&& rg, const Compare& comp = Compare(), const Allocator& alloc = Allocator() ); | (12) | (since C++23) |
template< container-compatible-range<value_type> R > set( std::from_range_t, R&& rg, const Allocator& alloc ) : set(std::from_range, std::forward<R>(rg), Compare(), alloc) { } | (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
)
. If multiple elements in the range have keys that compare equivalent, it is unspecified which element is inserted (pending LWG2844).other
. If | (since C++11) |
During class template argument deduction, only the first argument contributes to the deduction of the container's | (since C++23) |
other
using move semantics. If alloc
is not provided, allocator is obtained by move-construction from the allocator belonging to other
. During class template argument deduction, only the first argument contributes to the deduction of the container's | (since C++23) |
init
.If multiple elements in the range have keys that compare equivalent, it is unspecified which element is inserted (pending LWG2844).rg
. If multiple elements in the range have keys that compare equivalent, it is unspecified which element is inserted (pending LWG2844).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 [ first , last ) to copy the elements from |
rg | - | a container compatible range, that is, an input_range whose elements are convertible to value_type |
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 |
Type requirements | ||
-InputIt must meet the requirements of LegacyInputIterator. |
||
-Compare must meet the requirements of Compare. |
||
-Allocator must meet the requirements of Allocator. |
N = std::distance(first, last)
in general, linear in N
if the range is already sorted by value_comp()
.other
.alloc
is given and alloc != other.get_allocator()
, then linear.N = init.size()
in general, linear in N
if init
is already sorted by value_comp()
.N = ranges::distance(rg)
in general, linear in N
if the range is already sorted by value_comp()
.Calls to Allocator::allocate
may throw.
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.rev.reqmts]/17, and a more direct guarantee is under consideration via LWG 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 | Comment |
---|---|---|---|
__cpp_lib_containers_ranges | 202202L | (C++23) | Ranges-aware construction and insertion; overloads (12,13) |
#include <cmath> #include <iostream> #include <set> #include <string> struct Point { double x, y; }; struct PointCmp { bool operator()(const Point& lhs, const Point& rhs) const { return std::hypot(lhs.x, lhs.y) < std::hypot(rhs.x, rhs.y); } }; int main() { // (1) Default constructor std::set<std::string> a; a.insert("cat"); a.insert("dog"); a.insert("horse"); for (auto& str : a) std::cout << str << ' '; std::cout << '\n'; // (2) Iterator constructor std::set<std::string> b(a.find("dog"), a.end()); for (auto& str : b) std::cout << str << ' '; std::cout << '\n'; // (3) Copy constructor std::set<std::string> c(a); c.insert("another horse"); for (auto& str : c) std::cout << str << ' '; std::cout << '\n'; // (4) Move constructor std::set<std::string> d(std::move(a)); for (auto& str : d) std::cout << str << ' '; std::cout << '\n'; std::cout << "moved-from set is "; for (auto& str : a) std::cout << str << ' '; std::cout << '\n'; // (5) Initializer list constructor std::set<std::string> e { "one", "two", "three", "five", "eight" }; for (auto& str : e) std::cout << str << ' '; std::cout << '\n'; // custom comparison std::set<Point, PointCmp> z = { { 2, 5 }, { 3, 4 }, { 1, 1 } }; z.insert({ 1, -1 }); // this fails because the magnitude of 1,-1 equals 1,1 for (auto& p : z) std::cout << '(' << p.x << ',' << p.y << ") "; std::cout << '\n'; }
Output:
cat dog horse dog horse another horse cat dog horse cat dog horse moved-from set is eight five one three two (1,1) (3,4) (2,5)
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
DR | Applied to | Behavior as published | Correct behavior |
---|---|---|---|
LWG 2193 | C++11 | the default constructor is explicit | made non-explicit |
assigns values to the container (public member function) |
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