std::get(std::pair)
Defined in header <utility> | | |
|---|---|---|
| (1) | |
template< size_t I, class T1, class T2 > typename std::tuple_element<I, std::pair<T1,T2> >::type& get( pair<T1, T2>& p ); | (since C++11) (until C++14) | |
template< size_t I, class T1, class T2 > constexpr std::tuple_element_t<I, std::pair<T1,T2> >& get( pair<T1, T2>& p ); | (since C++14) | |
| (2) | |
template< size_t I, class T1, class T2 > const typename std::tuple_element<I, std::pair<T1,T2> >::type& get( const pair<T1,T2>& p ); | (since C++11) (until C++14) | |
template< size_t I, class T1, class T2 > constexpr const std::tuple_element_t<I, std::pair<T1,T2> >& get( const pair<T1,T2>& p ); | (since C++14) | |
| (3) | |
template< size_t I, class T1, class T2 > typename std::tuple_element<I, std::pair<T1,T2> >::type&& get( std::pair<T1,T2>&& p ); | (since C++11) (until C++14) | |
template< size_t I, class T1, class T2 > constexpr std::tuple_element_t<I, std::pair<T1,T2> >&& get( std::pair<T1,T2>&& p ); | (since C++14) | |
template< size_t I, class T1, class T2 > constexpr const std::tuple_element_t<I, std::pair<T1,T2> >&& get( const std::pair<T1,T2>&& p ); | (4) | (since C++17) |
template <class T, class U> constexpr T& get(std::pair<T, U>& p); | (5) | (since C++14) |
template <class T, class U> constexpr const T& get(const std::pair<T, U>& p); | (6) | (since C++14) |
template <class T, class U> constexpr T&& get(std::pair<T, U>&& p); | (7) | (since C++14) |
template <class T, class U> constexpr const T&& get(const std::pair<T, U>&& p); | (8) | (since C++17) |
template <class T, class U> constexpr T& get(std::pair<U, T>& p); | (9) | (since C++14) |
template <class T, class U> constexpr const T& get(const std::pair<U, T>& p); | (10) | (since C++14) |
template <class T, class U> constexpr T&& get(std::pair<U, T>&& p); | (11) | (since C++14) |
template <class T, class U> constexpr const T&& get(const std::pair<U, T>&& p); | (12) | (since C++17) |
使用类似元组的接口从一对中提取元素。
基于索引的重载%281-4%29如果索引失败，则无法编译I既不是0也不是1。
基于类型的重载%285-12%29如果类型失败，则无法编译T和U都是一样的。
参数
p | - | pair whose contents to extract |
|---|
返回值
1-4%29返回对p.first如果I==0以及引用p.second如果I==1...
5-8%29返回对p.first...
9-12%29返回对p.second...
例外
noexcept规格：
noexcept
例
二次
#include <iostream>
#include <utility>
int main()
{
auto p = std::make_pair(1, 3.14);
std::cout << '(' << std::get<0>(p) << ", " << std::get<1>(p) << ")\n";
std::cout << '(' << std::get<int>(p) << ", " << std::get<double>(p) << ")\n";
}二次
产出：
二次
(1, 3.14)
(1, 3.14)二次
另见
std::get(std::tuple) | tuple accesses specified element (function template) |
|---|---|
std::get(std::array) | accesses an element of an array (function template) |
std::get(std::variant) (C++17) | reads the value of the variant given the index or the type (if the type is unique), throws on error (function template) |
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