虚拟继承图示

在多级、多重继承中有以下两种关系

前者是普通继承，后者是虚拟继承，A类是虚基类，这种继承又称共享继承

普通继承

class A{...};
class B: public A{...};
class C: public A{...};
class D: public B, public C{...};

虚拟继承

class A{...};
class B: virtual public A{...};
class C: virtual public A{...};
class D: public B, public C{...};