函数重载对象hirearchy 在C++中，如果你有以下的 struct Base { }; struct Derived1 : Base { }; struct Derived2 : Derived1 { }; struct Derived3 : Derived2 { }; void f(const Derived2&) { std::cout << "Derived2" << std::endl; } void f(const Derived1&) { std::cout << "Derived1" << std::endl; } int main() { f(Derived3()); return 0; } struct Base { }; 结构Derived1:Base { }; 结构Derived2:Derived1 { }; 结构Derived3:Derived2 { }; 无效f（常数派生2&） { STD：：CUT< P>引用的是C++ + < /P>

在尝试解析要调用的函数时，如果参数类型中没有直接匹配，编译器必须对参数所需的转换进行排序，以便选择最佳候选

对于与继承层次结构中的对象相关的转换：

3) If Mid is derived (directly or indirectly) from Base, and Derived is derived (directly or indirectly) from Mid
a) Derived* to Mid* is better than Derived* to Base*
b) Derived to Mid& is better than Derived to Base&
c) Base::* to Mid::* is better than Base::* to Derived::*
d) Derived to Mid is better than Derived to Base
e) Mid* to Base* is better than Derived* to Base*
f) Mid to Base& is better than Derived to Base&
g) Mid::* to Derived::* is better than Base::* to Derived::*
h) Mid to Base is better than Derived to Base

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案例b）适用于您的示例。

谢谢，您能解释一下c）Base::*到Mid:*的含义吗？：*比Base:*到派生：：*