std::unordered_multimap<Key,T,Hash,KeyEqual,Allocator>::swap
来自 cppreference.com
void swap( unordered_multimap& other ); |
(自 C++11 起) (直到 C++17) |
|
void swap( unordered_multimap& other ) noexcept(/* see below */); |
(自 C++17 起) | |
将容器的内容与other的内容交换。不调用任何单个元素上的移动、复制或交换操作。
所有迭代器和引用保持有效。 end()
迭代器将失效。 Hash
和 KeyEqual
对象必须是 可交换的,并且它们使用对非成员 swap
的无限定调用来交换。
如果std::allocator_traits<allocator_type>::propagate_on_container_swap::value 为 true,则使用对非成员 |
(自 C++11 起) |
内容 |
[编辑] 参数
other | - | 要交换内容的容器 |
[编辑] 返回值
(无)
[编辑] 异常
|
(直到 C++17) |
noexcept 规范:
noexcept(std::allocator_traits<Allocator>::is_always_equal::value && std::is_nothrow_swappable<Hash>::value |
(自 C++17 起) |
[编辑] 复杂度
常数。
[编辑] 示例
运行此代码
#include <iostream> #include <string> #include <utility> #include <unordered_map> // print out a std::pair template<class Os, class U, class V> Os& operator<<(Os& os, const std::pair<U, V>& p) { return os << p.first << ':' << p.second; } // print out a container template<class Os, class Co> Os& operator<<(Os& os, const Co& co) { os << '{'; for (auto const& i : co) os << ' ' << i; return os << " }\n"; } int main() { std::unordered_multimap<std::string, std::string> m1{{"γ", "gamma"}, {"β", "beta"}, {"α", "alpha"}, {"γ", "gamma"}}, m2{{"ε", "epsilon"}, {"δ", "delta"}, {"ε", "epsilon"}}; const auto& ref = *(m1.begin()); const auto iter = std::next(m1.cbegin()); std::cout << "──────── before swap ────────\n" << "m1: " << m1 << "m2: " << m2 << "ref: " << ref << "\niter: " << *iter << '\n'; m1.swap(m2); std::cout << "──────── after swap ────────\n" << "m1: " << m1 << "m2: " << m2 << "ref: " << ref << "\niter: " << *iter << '\n'; // Note that every iterator referring to an element in one container before // the swap refers to the same element in the other container after the swap. // Same is true for references. }
可能的输出
──────── before swap ──────── m1: { α:alpha β:beta γ:gamma γ:gamma } m2: { δ:delta ε:epsilon ε:epsilon } ref: α:alpha iter: β:beta ──────── after swap ──────── m1: { δ:delta ε:epsilon ε:epsilon } m2: { α:alpha β:beta γ:gamma γ:gamma } ref: α:alpha iter: β:beta
[编辑] 另请参阅
专门化 std::swap 算法 (函数模板) |