A virtual function is a member function that you expect to be redefined in derived classes. When you refer to a derived class object using a pointer or a reference to the base class, you can call a virtual function for that object and execute the derived class's version of the function.
不可能,问题是,按照虚函数的作用来讲,虚构造函数完全没有意义。当你声明一个类的时候,其类型就是确定的,只需调用一次构造函数即可。我用 VC 6 做了一下试验,如果你用 virtual 来修饰构造函数的话,编译器会发出错误信息:
'inline' is the only legal storage class for constructors
也就是说,用来修饰构造函数的关键字只能是 inline 或则没有。