第13章 類繼承

13.11 編程練習

第二題

1頭文件源碼："classic.h"

 1 #ifndef CLASSIC_H_INCLUDED
 2 #define CLASSIC_H_INCLUDED
 3 
 4 class Cd
 5 {
 6 private:
 7     char *performers;
 8     char *label;
 9     int selections;
10     double playtime;
11 public:
12     Cd(char * s1, char * s2, int n, double x);
13     Cd();
14     Cd(const Cd & C);
15     virtual ~Cd();
16     virtual void Report() const;
17     Cd & operator=(const Cd &d);
18 };
19 
20 class Classic : public Cd
21 {
22 private:
23     char *details;
24 public:
25     Classic(char * s0, char * s1, char * s2, int n, double x);
26     Classic() {}
27     Classic(const Classic & C);
28     Classic(char * s0, const Cd  & d);
29     ~Classic();
30     virtual void Report() const;
31     Classic & operator=(const Classic & C);
32 
33 };
34 
35 #endif // CLASSIC_H_INCLUDED

2 頭文件實現：

  1 #include <iostream>
  2 #include <cstring>
  3 #include "classic.h"
  4 
  5 using std::cout;
  6 using std::endl;
  7 
  8 Cd::Cd(char * s1, char * s2, int n, double x)
  9 {
 10     int len1 = std::strlen(s1);
 11     int len2= std::strlen(s2);
 12     performers = new char[len1+1];
 13     label = new char[len2+1];
 14     std::strcpy(performers, s1);
 15     std::strcpy(label, s2);
 16     selections = n;
 17     playtime = x;
 18 }
 19 
 20 Cd::Cd()
 21 {
 22     performers = 0;
 23     label = 0;
 24     selections = 0;
 25     playtime = 0.0;
 26 }
 27 
 28 Cd::Cd(const Cd & C)
 29 {
 30     int len1 = std::strlen(C.performers);
 31     int len2= std::strlen(C.label);
 32     performers = new char[len1+1];
 33     label = new char[len2+1];
 34     std::strcpy(performers, C.performers);
 35     std::strcpy(label, C.label);
 36     selections = C.selections;
 37     playtime = C.playtime;
 38 }
 39 Cd::~Cd()
 40 {
 41     delete [] performers;
 42     delete [] label;
 43 }
 44 
 45 void Cd::Report() const
 46 {
 47     cout << "performers: " << performers << endl;
 48     cout << "label: " << label << endl;
 49     cout << "selection: " << selections << endl;
 50     cout << "playtime: " << playtime << endl;
 51 
 52 }
 53 
 54 Cd & Cd::operator=(const Cd &C)
 55 {
 56     if(this == &C)
 57         return *this;
 58     int len1 = std::strlen(C.performers);
 59     int len2= std::strlen(C.label);
 60     performers = new char[len1+1];
 61     label = new char[len2+1];
 62     std::strcpy(performers, C.performers);
 63     std::strcpy(label, C.label);
 64     selections = C.selections;
 65     playtime = C.playtime;
 66     return *this;
 67 }
 68 
 69 
 70 Classic::Classic(char * s0, char * s1, char * s2, int n, double x):Cd(s1, s2, n, x)
 71 {
 72     int len = std::strlen(s0);
 73     details = new char[len+1];
 74     std::strcpy(details, s0);
 75 }
 76 
 77 
 78 
 79 Classic::Classic(char * s0, const Cd &C):Cd(C)
 80 {
 81     details = new char[std::strlen(s0)+1];
 82     std::strcpy(details, s0);
 83 }
 84 
 85 Classic::Classic(const Classic & C):Cd(C)
 86 {
 87     int len = std::strlen(C.details);
 88     details = new char[len+1];
 89     std::strcpy(details, C.details);
 90 }
 91 
 92 Classic::~Classic()
 93 {
 94     delete [] details;
 95 }
 96 
 97 void Classic::Report() const
 98 {
 99     Cd::Report();
100     cout << "details: " << details << endl;
101 }
102 
103 Classic & Classic::operator=(const Classic & C)
104 {
105     if(this == &C)
106         return *this;
107     Cd::operator=(C);
108     delete [] details;
109     int len = std::strlen(C.details);
110     details = new char[len+1];
111     std::strcpy(details, C.details);
112     return *this;
113 }