class BC
{
public:
    BC( )
    {
        x = y = -1;
    }
private:
    int x, y;
};
class DC : public BC
{
public:
    DC( )
    {
        x = y = -1;//错误，不能构造基类的私有成员  error C2248: “B::x”: 无法访问 private 成员(在“B”类中声明)
    }
private:
    string  S;
};

class BC
{
public:
    BC( )
    {
        x = y = -1;
    }
private:
    int x, y;
};
class DC : public BC
{
public:
    DC( )
    {
        BC( );//这是构造后才调用，语义错误
    }
private:
    string  S;
};

class BC
{
public:
    BC( )
    {
        x = y = -1;
    }
private:
    int x, y;
};
class DC : public BC
{
public:
    DC( ) : BC( ), S("派生类"), { }//初始化列表
private:
    string  S;
};

class Team
{
public:
    Team(int len =100)
    {
        names = new string[maxno = len ];
        //基类构造函数完成其成员初始化，供派生类构造使用。
    }
protected:
    string* names;
    int     maxno;
};

class BaseballTeam : public Team
{
public:
    BaseballTeam(const string s[], int si)
        : Team(si)//为支持派生类构造本意，必须明确调用基类构造函数。

    {
        for(int i=0; i<si; i++)
            names[i] = s[i];
            //派生类构造函数执行前，基类构造必须完成。

    }
};

class BC
{
public:
    BC( )
    {
        sBC = new char[3];
        cout << "BC allocates 3 bytes.\n";
    }
    ~BC( )
    {
        delete [ ] sBC;
        cout << "BC free 3 bytes.\n";
    }
private:
    char* sBC;
};
class DC : public BC
{
public:
    DC( )
    {
        sDC = new char[5];
        cout << "DC allocates 5 bytes.\n";
    }
    ~DC( )
    {
        delete [ ] sDC;
        cout << "DC free 5 bytes.\n";
    }
private:
    char* sDC;
};
int main( )
{
    DC d;
    cout << “-------” << endl;
    return 0;
}