一个类有多少默认方法？ [英] How Many default methods does a class have?

问题描述

对不起，这可能看起来很简单，但有人问我这个，我不知道确定。

一个空的C ++类有什么功能？ / p>

构造函数，
复制构造函数，
赋值，
析构函数

是吗？

解决方案

在C ++ 03中有4个：

• 默认构造函数：只有在
  没有用户定义的构造函数声明为
  时才声明。使用时定义




• 复制构造函数 - 仅在用户尚未声明时声明。




破坏者与上述相同

：

• 移动构造函数

编译器也可能无法生成其中的一些。例如，如果类包含例如引用（或任何不能被复制分配的其他内容），那么编译器将无法为您生成副本赋值运算符。 有关详情，请阅读此

Sorry, this might seem simple, but somebody asked me this, and I don't know for certain.

An empty C++ class comes with what functions?

Constructor, Copy Constructor, Assignment, Destructor?

Is that it? Or are there more?

解决方案

In C++03 there are 4:

• Default constructor: Declared only if no user-defined constructor is declared. Defined when used

• Copy constructor - declared only if the user hasn't declared one. Defined if used

• Copy-assignment operator same as above

• Destructor same as above

In C++11 there are two more:

• Move constructor
• Move-assignment operator

It is also possible that the compiler won't be able to generate some of them. For example, if the class contains, for example, a reference (or anything else that cannot be copy-assigned), then the compiler won't be able to generate a copy-assignment operator for you. For more information read this

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