std::get(std::tuple)
| (1) | |
|---|---|---|
template< std::size_t I, class... Types > typename std::tuple_element<I, tuple<Types...> >::type& get( tuple<Types...>& t ); | (since C++11) (until C++14) | |
template< std::size_t I, class... Types > constexpr std::tuple_element_t<I, tuple<Types...> >& get( tuple<Types...>& t ); | (since C++14) | |
| (2) | |
template< std::size_t I, class... Types > typename std::tuple_element<I, tuple<Types...> >::type&& get( tuple<Types...>&& t ); | (since C++11) (until C++14) | |
template< std::size_t I, class... Types > constexpr std::tuple_element_t<I, tuple<Types...> >&& get( tuple<Types...>&& t ); | (since C++14) | |
| (3) | |
template< std::size_t I, class... Types > typename std::tuple_element<I, tuple<Types...> >::type const& get( const tuple<Types...>& t ); | (since C++11) (until C++14) | |
template< std::size_t I, class... Types > constexpr std::tuple_element_t<I, tuple<Types...> >const& get( const tuple<Types...>& t ); | (since C++14) | |
template< std::size_t I, class... Types > constexpr std::tuple_element_t<I, tuple<Types...> >const&& get( const tuple<Types...>&& t ); | (4) | (since C++17) |
template< class T, class... Types > constexpr T& get(tuple<Types...>& t); | (5) | (since C++14) |
template< class T, class... Types > constexpr T&& get(tuple<Types...>&& t); | (6) | (since C++14) |
template< class T, class... Types > constexpr const T& get(const tuple<Types...>& t); | (7) | (since C++14) |
template< class T, class... Types > constexpr const T&& get(const tuple<Types...>&& t); | (8) | (since C++17) |
1-4%29提取Ith元组中的元素。I中的整数值。[0, sizeof...(Types))...
5-8%29提取元组的元素。t他的类型是T如果元组有多个该类型的元素，则无法编译。
参数
t | - | tuple whose contents to extract |
|---|
返回值
的选定元素的引用。t...
例外
noexcept规格：
noexcept
例
二次
#include <iostream>
#include <string>
#include <tuple>
int main()
{
auto t = std::make_tuple(1, "Foo", 3.14);
// index-based access
std::cout << "(" << std::get<0>(t) << ", " << std::get<1>(t)
<< ", " << std::get<2>(t) << ")\n";
// type-based access
std::cout << "(" << std::get<int>(t) << ", " << std::get<const char*>(t)
<< ", " << std::get<double>(t) << ")\n";
}二次
产出：
二次
(1, Foo, 3.14)
(1, Foo, 3.14)二次
另见
std::get(std::array) | accesses an element of an array (function template) |
|---|---|
std::get(std::pair) (C++11) | accesses an element of a pair (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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