虚函数多态注意点

#include <iostream>#include <string.h>using namespace std;class Base{public:virtual void Fun(int a = 10){cout<<"Base::"<<a<<endl;}};class Drived: public Base{public:void Fun(int a = 20){cout<<"Drived::"<<a<<endl;}};int main(){Drived d ;Base *b= &d;b->Fun();system("pause");}/*运行结果： Drived::"10  //说明 虚函数动态绑定到子类 但缺省实参是在编译时候确定的10*/