default_arg.cpp

/**
 * @file first_example.cpp
 * @brief 虚函数中默认参数
 * 规则：虚函数是动态绑定的，默认参数是静态绑定的。默认参数的使用需要看指针或者应用本身的类型，而不是对象的类型！
 * @author 光城
 * @version v1
 * @date 2019-07-24
 */

#include <iostream>
using namespace std;

class Base {
public:
  virtual void fun(int x = 10) { cout << "Base::fun(), x = " << x << endl; }
};

class Derived : public Base {
public:
  virtual void fun(int x = 20) { cout << "Derived::fun(), x = " << x << endl; }
};

int main() {
  Derived d1;
  Base *bp = &d1;
  bp->fun(); // 10
  return 0;
}