example25.cpp

来自「Advanced Internet Programming Lecture 2 」· C++ 代码 · 共 47 行

#include <iostream>
using namespace std;

class base {
public:
  virtual void vfunc() {
    cout << "This is base's vfunc().\n";
  }
};

class derived1 : public base {
public:
  void vfunc() {
    cout << "This is derived1's vfunc().\n";
  }
};

class derived2 : public derived1 {
public:
/* vfunc() not overridden by derived2.
   In this case, since derived2 is derived from
   derived1, derived1's vfunc() is used.
*/
};

int main()
{
  base *p, b;
  derived1 d1;
  derived2 d2;

  // point to base
  p = &b;
  p->vfunc(); // access base's vfunc()

  // point to derived1
  p = &d1;
  p->vfunc(); // access derived1's vfunc()

  // point to derived2
  p = &d2;
 p->vfunc(); // use derived1's vfunc()

  return 0;
}