一到关于c＋＋继承和多态的题
1
class base
2
{
3
public:
4 base()
5
{
6 cout <<" base::val "<<endl;
7 val = 12345;
8 print();
9
}
10 base(int x)
11 {
12 val = x;
13 cout << " "<<endl;
14 }
15 virtual void print()
16 {
17 cout << " base:print(), val = "<<val<<endl;
18 }
19 base & operator = (int x)
20 {
21 val = x;
22 cout <<" base::operator, val = "<<x<<endl;
23 return *this;
24 }
25 void relase()
26 {
27 cout << " base::relase" <<endl;
28 }
29 ~base()
30 {
31 cout << " ~base::val = "<< val <<endl;
32 }
33protected:
34 int val;
35
};
36
37class deiver:public base
38{
39public:
40 deiver()
41 {
42 cout << " deiver::val "<<endl;
43 }
44
45 deiver(int x)
46 {
47 val = x;
48 print();
49 }
50 void print()
51 {
52 cout << " deiver::print(), val = "<< val <<endl;
53 }
54 void relase()
55 {
56 cout << " deiver::relase, val = "<<val<<endl;
57 }
58 deiver & operator = (int x)
59 {
60 val = x;
61 cout <<" deiver::operator, val = "<<x<<endl;
62 return *this;
63 }
64 ~deiver()
65 {
66 cout << " deiver::~deiver "<<endl;
67 }
68};
69void des(base * b)
70{
71 b->print();
72 b->relase();
73}
74deiver de = 98765;
75int main()
76{
77 deiver * dee = new deiver;
78 *(base *)dee = 100;
79 des(dee);
80 delete dee;
81 return 0;
82}
83
84
class base2
{
3
public:4
base()5
{
6
cout <<" base::val "<<endl;7
val = 12345;8
print();9
}10
base(int x)11
{12
val = x;13
cout << " "<<endl;14
}15
virtual void print()16
{17
cout << " base:print(), val = "<<val<<endl;18
}19
base & operator = (int x)20
{21
val = x;22
cout <<" base::operator, val = "<<x<<endl;23
return *this;24
}25
void relase()26
{27
cout << " base::relase" <<endl;28
}29
~base()30
{31
cout << " ~base::val = "<< val <<endl;32
}33
protected:34
int val;35
};36
37
class deiver:public base38
{39
public:40
deiver()41
{42
cout << " deiver::val "<<endl;43
}44
45
deiver(int x)46
{47
val = x;48
print();49
}50
void print()51
{52
cout << " deiver::print(), val = "<< val <<endl;53
}54
void relase()55
{56
cout << " deiver::relase, val = "<<val<<endl;57
}58
deiver & operator = (int x)59
{60
val = x;61
cout <<" deiver::operator, val = "<<x<<endl;62
return *this;63
}64
~deiver()65
{66
cout << " deiver::~deiver "<<endl;67
}68
};69
void des(base * b)70
{71
b->print();72
b->relase();73
}74
deiver de = 98765;75
int main()76
{77
deiver * dee = new deiver;78
*(base *)dee = 100;79
des(dee);80
delete dee;81
return 0;82
}83
84
