类的构造函数-》类的成员对象的构造函数-》派生类的构造函数
我们来看下面一段代码:
class B1
{
public:
B1(int i){cout<<"constructing B1 "<<i<<endl;}
};
class B2
{
public:
B2(int j){cout<<"constructing B2 "<<j<<endl;}
};
class B3
{
public:
B3()