初始化大小为std :: vector的数组

Question

This won't compile, because the constructor that takes the size (something like vector::vector( size_t ) ) is explicit :

constexpr auto n = 16;
std::vector< std::unique_ptr< int > > v[ 2 ]{ { n }, {} };

So how can I initialize v[ 0 ] with n default constructed elements, and leave v[ 1 ] empty?

Answer 1

您可以显式构造临时对象，例如

std::vector< std::unique_ptr< int > > v[ 2 ]{ std::vector< std::unique_ptr< int > >{ n }, {} };