Defining a Copy Constructor for a Reference Class Type

最新推荐文章于 2021-04-05 22:49:49 发布

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#C++CLI #Reference Class #Copy Constructor

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本文深入探讨了C++中复制构造函数的概念、定义及应用，特别关注引用类类型的值传递场景，通过实例展示了如何正确实现复制构造函数，并讨论了复制构造函数与参数类型的关系。

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You are unlikely to be doing it very often, but if you do pass objects of a reference class type to a function by value, you must implement a public copy constructor; this situation can arise with the Standard Template Library implementation for the CLR, which you will learn about in Chapter 10.

The parameter to the copy constructor must be a const reference, so you would defi ne the copy constructor for the Box class like this:

Box(const Box% box) : Length(box.Length), Width(box.Width), Height(box.Height)

{ }

In general, the form of the copy constructor for a ref class T that allows a ref type object of type T to be passed by value to a function is:

T(const T% t)

{

// Code to make the copy...

}

Occasionally, you may also need to implement a copy constructor that takes an argument that is a handle. Here ’ s how you could do that for the Box class:

Box(const Box^ box) : Length(box- > Length), Width(box- > Width), Height(box- > Height)

{}

As you can see, there is little difference between this and the previous version.