复杂的dynamic_cast在c

我在C中有以下情况：

>抽象基类Abstract1和Abstract2.他们是无关的.
>一个派生自Abstract1和Abstract2的Foo类

我在一个编译单位,我没有关于Foo类的信息(没有声明,没有定义).只有Abstract1和Abstract2是已知的.
(实际上,Foo甚至在DLL中定义)

将dynamic_cast允许从Abstract1 *转换为Abstract2 *？这是标准吗？

解决方法

你所描述的是一种所谓的交叉角色.对于dynamic_cast< T(v),标准在[expr.dynamic.cast] / 8

If C is the class type to which T points or refers,the run-time
check logically executes as follows:

• If,in the most derived object pointed (referred) to by v,v points (refers) to a public base class subobject of a C object [..]

• Otherwise,if v points (refers) to a public base class subobject of the most derived object,and the type of the most derived object
  has a base class,of type C,that is unambiguous and public,the
  result points (refers) to the C subobject of the most derived
  object.

即使没有关于Foo在包含演员的翻译单元中的存在的信息,这将会工作.

你也应该看看this question.

原文地址：https://www.jb51.cc/c/110250.html