4.24

 1 #include <iostream>
 2 using namespace std;
 3 class DataType
 4 {
 5 public:
 6     DataType(int i)
 7     {
 8         data.i = i;
 9         type = INT;
10     }
11     DataType(char c)
12     {
13         data.c = c;
14         type = CHAR;
15     }
16     DataType(float f)
17     {
18         data.f = f;
19         type = FLOAT;
20     }
21     void Show()
22     {
23         switch (type)
24         {
25         case CHAR:
26             cout << data.c << endl;
27             break;
28         case INT:
29             cout << data.i << endl;
30             break;
31         case FLOAT:
32             cout << data.f << endl;
33             break;
34         default:
35             break;
36         }
37     }
38 private:
39     enum TYPE { INT, CHAR, FLOAT };
40     union DATA
41     {
42         int i;
43         char c;
44         float f;
45     };
46     TYPE type;
47     DATA data;
48 };
49 int main()
50 {
51     DataType a('c');
52     a.Show();
53     DataType b(960);
54     b.Show();
55     DataType c(265.12f);
56     c.Show();
57     return 0;
58 }

 1 #include <iostream>
 2 
 3 using namespace std;
 4 
 5 class Tree {
 6 public:
 7     Tree(int age = 0) : m_age(age) {}
 8     void grow(int years) {
 9         m_age += years;
10     }
11     int age() const {
12         return m_age;
13     }
14 private:
15     int m_age;
16 };
17 
18 int main() {
19     Tree t(10); 
20     cout << "树龄为：" << t.age() << endl;
21     t.grow(5); 
22     cout << "长了5年后树龄为：" << t.age() << endl;
23     return 0;
24 }

 1 #include <iostream>
 2 using namespace std;
 3 
 4 class   CPU {
 5 public:
 6  CPU(int i, int j, int m, bool n);    
 7  void   show();    
 8 private:
 9  int m_Hz;
10  int m_zijie;
11  int m_he;
12  bool m_chaopin;
13 };
14 void  CPU::show()
15 {
16  cout << m_Hz << endl << m_zijie << endl << m_he << endl;
17  if (m_chaopin == 1)
18   cout << "true" << endl;
19  else
20   cout << "false" << endl;
21 }
22 CPU::CPU(int i, int j, int m, bool n) 
23 {
24  m_Hz = i;
25  m_zijie = j;
26  m_he = m;
27  m_chaopin = n;
28 }