std::tuple<int, std::string> tu{ 2,"12iop" };

#include <tuple>

struct Point
{
 int x;
 int y;
};
 
void main()
{
 std::tuple<int, std::string> t1{ 1,"qwer" }; // 一个由int和字符串组成的tuple
 constexpr std::tuple<int, void*> t2{ 1,nullptr }; // 一个由int和void*组成的tuple
 std::tuple<int, Point> t3{ 1,{20,89} }; // 一个由int和Point结构体组成的tuple
 std::tuple<int, char, std::string> t4{ 1,'t',"qwer" }; // 一个由int、char、字符串组成的tuple
}

struct Point
{
 int x;
 int y;
};
 
void main()
{
 std::tuple<int, std::string> t1{ 1,"qwer" };
 constexpr std::tuple<int, void*> t2{ 10,nullptr };
 std::tuple<int, Point> t3{ 1,{20,89} };
 std::tuple<int, char, std::string> t4{ 1,'t',"qwer" };
 
 std::cout << std::get<0>(t1) << std::endl; // 1
 
 constexpr int n2 = std::get<0>(t2);
 std::cout << n2 << std::endl; // 10
 
 auto s = std::get<char>(t4);
 std::cout << s << std::endl; // t
}

std::tuple<int, std::string> t5{ 1,"qwer" };
 
if (t1 == t5)
{
 std::cout << "==" << std::endl;
}

template<typename... _Types>
class tuple;

struct allocator_arg_t
{};
 
template<>
class tuple<>
{
public:
 typedef tuple<> _Myt;
 
 constexpr tuple() noexcept
 {}
 
 template<typename _Alloc>
 tuple(allocator_arg_t, const _Alloc&) noexcept
 {}
 
 constexpr tuple(const tuple&) noexcept
 {}
 
 template<class _Alloc>
 tuple(allocator_arg_t, const _Alloc&, const _Myt&) noexcept
 {}
 
 void swap(_Myt&) noexcept
 {}
 
 constexpr bool _Equals(const _Myt&) const noexcept
 {
 return true;
 }
 
 constexpr bool _Less(const _Myt&) const noexcept
 {
 return false;
 }
};

template<class _This,
class... _Rest>
class tuple<_This, _Rest...>
 : private tuple<_Rest...>
{
 // 内容
}

template<class _This,
class... _Rest>
class tuple<_This, _Rest...>
 : private tuple<_Rest...>
{ // recursive tuple definition
public:
 typedef _This _This_type;
 typedef tuple<_This, _Rest...> _Myt;
 typedef tuple<_Rest...> _Mybase;
 static const size_t _Mysize = 1 + sizeof...(_Rest);
 
 _Tuple_val<_This> _Myfirst; // 存储的元素
}

 constexpr tuple(): _Mybase(), _Myfirst()
 {}
 
 constexpr explicit tuple(const _This& _This_arg,
 const _Rest&... _Rest_arg)
 : _Mybase(_Rest_arg...),
 _Myfirst(_This_arg)
 {}
 
 tuple(const _Myt&) = default;
 tuple(_Myt&&) = default;

 template<class... _Other>
 _Myt& operator=(const tuple<_Other...>& _Right)
 { // assign by copying same size tuple
 _Myfirst._Val = _Right._Myfirst._Val;
 _Get_rest() = _Right._Get_rest();
 return (*this);
 }

template<class... _Other>
constexpr bool _Equals(const tuple<_Other...>& _Right) const
{
 static_assert(_Mysize == sizeof...(_Other), "comparing tuple to object with different size");
 return (_Myfirst._Val == _Right._Myfirst._Val && _Mybase::_Equals(_Right._Get_rest()));
}

_Mybase& _Get_rest() noexcept
{
 return (*this);
}
 
constexpr const _Mybase& _Get_rest() const noexcept
{
 return (*this);
}