std::set<Key,Compare,Allocator>::set
(1) | ||
set(); explicit set( const Compare& comp, |
||
explicit set( const Allocator& alloc ); |
(since C++11) | |
(2) | ||
template< class InputIt > set( InputIt first, InputIt last, |
||
template< class InputIt > set( InputIt first, InputIt last, const Allocator& alloc) |
(since C++14) | |
set( const set& other ); |
(3) | |
set( const set& other, const Allocator& alloc ); |
(3) | (since C++11) |
set( set&& other ); |
(4) | (since C++11) |
set( set&& other, const Allocator& alloc ); |
(4) | (since C++11) |
(5) | ||
set( std::initializer_list<value_type> init, const Compare& comp = Compare(), |
(since C++11) | |
set( std::initializer_list<value_type> init, const Allocator& alloc ) : set(init, Compare(), alloc) {} |
(since C++14) | |
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) |
The template parameter |
(since C++23) |
other
using move semantics. If alloc
is not provided, allocator is obtained by move-construction from the allocator belonging to other
.
The template parameter |
(since C++23) |
init
. If multiple elements in the range have keys that compare equivalent, it is unspecified which element is inserted (pending LWG2844).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 |
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
N
if the range is already sorted by value_comp()
.other
alloc
is given and alloc != other.get_allocator(), then linear.N
if init
is already sorted by value_comp()
.[edit] Exceptions
Calls to Allocator::allocate
may throw.
[edit] Notes
After container move construction (overload (4)), 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.
[edit] Example
#include <iostream> #include <string> #include <set> #include <cmath> 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)
[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 2193 | C++11 | the default constructor is explicit | made non-explicit |
[edit] See also
assigns values to the container (public member function) |