C++程序  |  52行  |  1.18 KB

//===----------------------------------------------------------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is dual licensed under the MIT and the University of Illinois Open
// Source Licenses. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

// <utility>

// template <class T1, class T2> struct pair

// template<size_t I, class T1, class T2>
//     typename tuple_element<I, std::pair<T1, T2> >::type&
//     get(pair<T1, T2>&);

#include <utility>
#include <cassert>

#if __cplusplus > 201103L
struct S {
   std::pair<int, int> a;
   int k;
   constexpr S() : a{1,2}, k(std::get<0>(a)) {}
   };

constexpr std::pair<int, int> getP () { return { 3, 4 }; }
#endif

int main()
{
    {
        typedef std::pair<int, short> P;
        P p(3, 4);
        assert(std::get<0>(p) == 3);
        assert(std::get<1>(p) == 4);
        std::get<0>(p) = 5;
        std::get<1>(p) = 6;
        assert(std::get<0>(p) == 5);
        assert(std::get<1>(p) == 6);
    }

#if __cplusplus > 201103L
    {
        static_assert(S().k == 1, "");
        static_assert(std::get<1>(getP()) == 4, "");
    }
#endif

}