std :: vector适用于不是默认可构造的类？ [英] std::vector works with classes that are not default constructible?

问题描述

我在几个地方读过std :: vector要求它的模板参数是默认可构造的。今天我只是尝试了它的一个类，有一个 delete d默认构造函数，我感到惊讶似乎是工作很好（与std :: vector的默认构造函数）。是这个可移植的行为，还是这是gcc的STL的实现细节，我应该假设向量要求它的模板参数是默认可构造的

I've read in several places that std::vector requires it's template argument to be default constructible. Today I just tried it with one of my classes that has a deleted default constructor, and to my surprise it seems to be working just fine (with std::vector's default constructor). Is this portable behavior, or is this an implementation detail of gcc's STL and should I assume vector to require it's template argument to be default constructible?

推荐答案

C ++ 03中的要求是存储在容器中的类型是 CopyConstructible 和可分配见§23.1集装箱要求）。但是，在C ++ 11中，这些要求是放宽的，并且倾向于适用于对容器执行的操作。因此，一个简单的默认构造没有要求（参见C ++ 11标准中的teble 96，§23.1）。

The requirement in C++03 is that types being stored in a container be CopyConstructible and Assignable (see §23.1 Container Requirements). However, in C++11 these requirements are relaxed, and tend to apply to the operations performed on the container. So a simple default construction has no requirements (see teble 96, §23.1 in C++11 standard).

一旦你试图复制一个向量，元素，您将满足 CopyInsertable ， CopyAssignable ， EmplaceConstructible ， MoveInsertable ， MoveAssignable 等要求

As soon as you try to copy a vector, or insert elements into it, you will meet the CopyInsertable, CopyAssignable, EmplaceConstructible, MoveInsertable, MoveAssignable etc. requirements

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