文档介绍：解释Public, Private和Protected的联系与区别？
什么是析构函数，它和构造函数的区别是什么？
三、指出下列各成员在不同类中的访问属性（共10分）
class A
class B: Protected A
cla3 = 12/21 =4/7 ）；
(public: D() ( cout« ' D' ;} );
class E:public A
( Public: C c; E() { cout<< 'E' ;} );
Class F:virtual public B, public D,public E
( Public: F() (cout«, F' ;}};
void main()
( A a; cout<<endl;
B b; cout«endl;
C c; cout«endl;
D d; cout<<endl;
E e; cout<<endl;
F f; cout<<endl;
2^ Class A
( Public: A() ( cout〈〈" ~A() (cout«,, Class B:public A
( Public: B() ( cout〈<" ~B() (cout«,, Class C:public B( Public: C() ( cout〈<" ~C() (cout<<w
constructing destructing
constructing destructing
constructing destructing
A” «endl;A" «endl;
B” «endl;B" «endl;
C” «endl;C" «endl;
｝；
｝；
｝；
程序结果是（注意格式）
3、#include<iostream. h>
class A
(public:
AO {}
A(int a) {x=a;)
A (A &a) {x=++a. x;}
void disp() {cout«z，x=z，<<x<<endl;} int x;
}；
void main()
( A sl(2), s2(sl);
si. disp ();
s2. disp () ; }
void main()
( complex cl (3, 4); double d;
d=+cl; cout<<d;
}
matrix
( public:
Matrix ()
( for(int i=0; i<2; i++)
For( int j=0; j<2; j++) mat[i][j]=0; }
Friend matrix operator+(matrix &a, matrix &b)
( matrix c;
For (int i=0; i<2; i++)
For (int j=0; j<2; j++) c. mat[i] [j]=a. mat[i] [j]+b. mat [i] [j];
Return c;
}
Void input ()
( for (int i=0; i<2; i++)
For(int j=0; j<2; j++) cin»mat[i] [j];
}
Void outp