18-4.txt

《C/C++完美演绎》源代码

/* 范例：18-4 */
#include <iostream.h>
class A
{
  public:
    A(){a=1;}
    void pp(){cout << "    a: " << &a << "\n";}
    int a;
};
class B:virtual public A
{
  public:
    B(){b=2;}
    void pp(){A::pp();cout << "    b: " << &b << "\n";}
    int b;
};

class C:virtual public A
{
  public:
    C(){c=3;}
    void pp(){A::pp();cout << "    c: " << &c << "\n";}
    int c;
};

class D:public B,public C
{
  public:
    D(){d=4;}
    void pp(){B::pp();C::pp();cout << "    d: " << &d <<"\n";}
    int d;
};
void main(void)
{
  A obj1; B obj2; C obj3; D obj4;
  cout <<" obj1: " <<sizeof(obj1) <<endl;  /* 取得对象obj1的大小 */
  cout <<"&obj1: " <<&obj1 <<endl; /* 取得对象obj1的开头地址 */
  obj1.pp();	/* 调用函数pp()来取得各个数据成员地址 */
  cout <<"================" <<endl;
  cout <<" obj2: " <<sizeof(obj2) <<endl;
  cout <<"&obj2: " <<&obj2 <<endl;
  obj2.pp();
  cout <<"================" <<endl;
  cout <<" obj3: " <<sizeof(obj3) <<endl;
  cout <<"&obj3: " <<&obj3 <<endl;
  obj3.pp();
  cout <<"================" <<endl;
  cout <<" obj4: " <<sizeof(obj4) <<endl;
  cout <<"&obj4: " <<&obj4 <<endl;
  obj4.pp();
  getchar();
}

程序执行结果：
obj1: 4
&obj1: 0065FE00
    a: 0065FE00
===============
 obj2: 12
&obj2: 0065FDF4
    a: 0065FDFC
    b: 0065FDF8
===============
 obj3: 12
&obj3: 0065FDE8
    a: 0065FDF0
    c: 0065FDEC
===============
 obj4: 24
&obj4: 0065FDD0
    a: 0065FDE4
    b: 0065FDD4
    a: 0065FDE4
    c: 0065FDDC
    d: 0065FDE0