注意类型和槽号
#include<iostream> using namespace std; class A { public: virtual void disp(int n){ cout<<"A::disp n="<<n<<endl; } }; class B:public A { public: virtual void disp(double m){ cout<<"B::disp m="<<m<<endl; } }; void fn(A &a) { a.disp(5.5); } int main() { B b; fn(b); return 0; }