/* 范例：17-7 */
#include <iostream.h>
class A
{
  public:
    A(){a=5;cout << "A Constructor\n";}
    int a;
};

class B:public A
{
  public:
    B(){A(); cout << "B Constructor\n";}
    int b;
};

void main()
{
  B obj1;
  getchar();
}

程序執行結果：
A Constructor
A Constructor
B Constructor