铸造智能指针 [英] Casting of smart pointers

问题描述

一段时间以来，我一直在使用Raw指针，现在我正在尝试使用智能指针。

I have been using Raw pointers for a while , now i am trying to use Smart Pointers.

如果ClassB是ClassA的子代。

if ClassB is child of ClassA.

我可以使用原始指针来完成此操作。

I can do this with raw pointers.

 ClassA* ptr = new ClassB;

此行将等同于上述行。

std::shared_ptr<ClassA> ptr = std::shared_ptr<ClassB>(new ClassB);

当ptr超出范围时，内存将被清除。

when ptr goes out of scope the memory will be cleared.

推荐答案

Kinda是。

Kinda是因为 std :: shared_ptr 比原始指针慢。如果您在其他地方传递了共享指针的副本，则不会释放对象，但是一旦所有共享指针都消失了，它就会被释放。

Kinda is because std::shared_ptr is slower than raw pointers. Object won't get deallocated if you passed a copy of the shared pointer somewhere else, but it will get deallocated once all the shared pointers to it are gone.

此外，引用计数器跟踪器是安全线程。

Furthermore, the reference counter tracker is safe-thread.

也 ClassA 不需要虚拟析构函数即可使共享指针正常工作。

Also ClassA need not have a virtual destructor for the shared pointer to work properly.

您可以想象，这些功能非常昂贵。

As you can imagine, these features are costly.

如果需要与原始指针相同的性能，则可以通过使用 std :: unique_ptr 来实现。但是，它是不可复制的，其用法可能会使C ++ 11中新引入的语言感到困惑。

If you need same performance as raw pointers, you can achieve it by utilizing std::unique_ptr. Though, it is non-copyable and its usage might confuse newly introduced to C++11.

除此之外，建议使用 std :: make_shared 和 std :: make_unique 用于初始化所述智能指针。

Aside from that, it is recommended to use std::make_shared and std::make_unique for initializing said smart pointers.

这篇关于铸造智能指针的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！