std :: unique_ptr用法 [英] std::unique_ptr usage

问题描述

std::unique_ptr<int> p1(new int);
std::unique_ptr<int> p2(new int);
p2=p1;

在这里看来p1不再是唯一的"，因为p2也引用了它.

It seems here that p1 is no longer "unique" since p2 refer to it also

这是合法的c ++吗?unique_ptr是否具有copy_semantics?如果否，并且仅具有移动语义，则在将p1分配给p2之后，是否将p1设置为NULL?

It is legal c++ ? Does unique_ptr have copy_semantics ? If no, and if it has only move semantics, is p1 set to NULL after assign it to p2 ?

好，所以正确的版本是

 p2=std::move(p1)

据此，在此分配之后，p1无效吗?和auto_ptr的区别在这里吗?明确指定所有权转移比隐式指定所有权更安全，因为我猜想auto_ptr就是这种情况

According to that, after this assign, p1 is not valid ? And the difference with auto_ptr is here? it is more safe to explictly specfiy transfer of ownership than implicitly as it is the case with auto_ptr I guess

推荐答案

std :: unique_ptr是不可分配和不可复制的.您需要使用std :: move();

std::unique_ptr is non-assignable and non-copyable. You need to use std::move();

如此

p1 = std::move(p2);

看看此处以获取更多信息.

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