《C++语言基础》程序阅读——继承和派生
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（1）
#include
using namespace std;
class Data
{
public:
Data(int i):x(i)
{
cout<<"A";
}
~Data()
{
cout<<"B";
}
private:
int x;
};
class Base
{
public:
Base(int i):b1(i)
{
cout<<"C";
}
~Base()
{
cout<<"D";
}
private:
int b1;
};
class Derived:public Base
{
public:
Derived (int i,int j):Base(i),d1(j)
{
cout<<"E";
}
~Derived()
{
cout<<"F";
}
private:
Data d1;
};
int main()
{
Derived obj(1,2);
return 0;
} （2）
#include
using namespace std;
class G
{
public:
static int m;
G( ) //构造函数
{
m++;
cout<<"G begins\n";
}
~G( )
{
cout<<"G ends\n";
m--;
}
};
int G::m=0;
class D:public G
{
public:
D( ) //构造函数
{
m++;
cout<<"D begins\n";
}
~D( )
{
cout<<"D ends\n" ;
m-- ;
}
};
int main( )
{
D objg;
cout< （3）
#include
using namespace std;
class A
{
private:
int x;
protected:
int y;
public:
int z;
A(int a,int b,int c)
{
x=a;
y=b;
z=c;
}
int Getx()
{
return x;
}
int Gety()
{
return y;
}
void ShowA()
{
cout<< "x="<using namespace std;
class Part //部件类
{
public:
Part();
Part(int i);
~Part();
private:
int val;
};
Part::Part()
{
val=0;
cout<<"调用Part的默认构造函数:"< 将Whole类的构造函数（见注释//问题2）改为下面形式，请解释出现的警告信息。
Whole::Whole(int p, int i,int j,int k): Part(p),two(i),one(j),data(k) //问题2自选阅读：若还想通过运行程序的方式掌握继承机制的运行过程，阅读并运行下面的程序
（1）
#include
using namespace std;
class A
{
public:
A()
{
cout<<"A";
}
~A()
{
cout<<"~A";
}
};
class B :public A
{
A *p;
public:
B()
{
cout<<"B";
p=new A();
}
~B()
{
cout<<"~B";
delete p;
}
};
int main()
{
B obj;
return 0;
} （2）
#include
using namespace std;
class A
{
protected:
int x;
public:
A(int x)
{
A::x=x;
cout<<"class A"< （3）
#include
using namespace std;
class my_base
{
int a,b;
public:
my_base(int x,int y)
{
a=x;
b=y;
}
virtual void show()
{
cout<<"base";
cout<#include
using namespace std;
class Animal //动物类
{
public:
Animal() {}
void eat(){
cout << "eat\n";
}
protected:
void play()
{
cout << "play\n";
}
private:
void drink()
{
cout << "drink\n";
}
};
class Giraffe: public Animal //长颈鹿类
{
public:
Giraffe() {}
void StrechNeck()
{
cout << "Strech neck \n";
}
private:
void take()
{
eat(); // 正确，公有继承下,基类的公有成员对派生类可见
drink(); // _______________
play(); // _______________
}
};
int main()
{
Giraffe gir; //定义派生类的对象
gir.eat(); // 正确，公有继承下,基类的公有成员对派生类对象可见
gir.play(); // _______________
gir.drink(); // _______________
gir.take(); // _______________
gir.StrechNeck(); // _______________
Animal ani;
ani.eat(); // _______________
ani.play(); // _______________
ani.drink(); // _______________
ani.take(); //错误，派生类的成员对基类对象（不论访问属性）不可见
ani.StrechNeck(); // _______________
return 0;
} （2）private继承方式下
#include
using namespace std;
class Animal
{
public:
Animal() {}
void eat()
{
cout << "eat\n";
}
protected:
void play()
{
cout << "play\n";
}
private:
void drink()
{
cout << "drink\n";
}
};
class Giraffe: private Animal
{
public:
Giraffe() {}
void StrechNeck()
{
cout << "Strech neck \n";
}
void take()
{
eat(); // _______________
drink(); // _______________
play(); // _______________
}
};
int main()
{
Giraffe gir;
gir.eat(); // _______________
gir.play(); // _______________
gir.drink(); // _______________
return 0;
} （3）protected继承方式下
#include
using namespace std;
class Animal
{
public:
Animal() {}
void eat()
{
cout << "eat\n";
}
protected:
void play()
{
cout << "play\n";
}
private:
void drink()
{
cout << "drink\n";
}
};
class Giraffe: protected Animal
{
public:
Giraffe() {}
void StrechNeck()
{
cout << "Strech neck \n";
}
void take()
{
eat(); // _______________
drink(); // _______________
play(); // _______________
}
};
int main()
{
Giraffe gir;
gir.eat(); // _______________
gir.play(); // _______________
gir.drink(); // _______________
return 0;
}