【C++ Primer Plus】编程练习答案——第9章

 1 // chapter09_golf.h
 2
 3 #ifndef LEARN_CPP_CHAPTER09_GOLF_H
 4 #define LEARN_CPP_CHAPTER09_GOLF_H
 5
 6 #include <cstring>
 7 #include <iostream>
 8
 9 const int Len = 40;
10 struct golf {
11     char fullname[Len];
12     int handicap;
13 };
14
15 void setgolf(golf &, const char *, int);
16 int setgolf(golf &);
17 void handicap(golf &, int);
18 void showgolf(const golf &);
19
20
21
22 #endif //LEARN_CPP_CHAPTER09_GOLF_H
23
24
25
26
27
28 // chapter09_golf.cpp
29
30 #include "chapter09_golf.h"
31
32 void setgolf(golf & g, const char * name, int hc) {
33     strcpy(g.fullname, name);
34     g.handicap = hc;
35 }
36
37 int setgolf(golf & g) {
38     using namespace std;
39     cout << "enter name: ";
40     cin.getline(g.fullname, Len);
41     cout << "enter hc: ";
42     cin >> g.handicap;cin.get();
43     if (strcmp("\0", g.fullname) == 0)
44         return 0;
45     return 1;
46 }
47
48 void handicap(golf & g, int hc) {
49     g.handicap = hc;
50 }
51
52 void showgolf(const golf & g) {
53     using namespace std;
54     cout << "name: " << g.fullname << endl;
55     cout << "hc: " << g.handicap << endl;
56 }
57
58
59
60
61
62 // run
63
64 void ch9_1() {
65     using namespace std;
66     golf arr_golf[3];
67     cout << "enter golf: ";
68     int i;
69     for (i = 0; i < 3; ++ i) {
70         if (setgolf(arr_golf[i]) == 0)
71             break;
72     }
73     cout << "enter done" << endl;
74     for (int j = 0; j < i; ++ j)
75         showgolf(arr_golf[j]);
76 }

 1 void ch9_2_strcount(std::string & str) {
 2     using namespace std;
 3     static int total = 0;
 4     int count = 0;
 5     cout << "\"" << str << "\" contains ";
 6     count = str.length();
 7     total += count;
 8     cout << count << " chars" << endl;
 9     cout << total << " chars total" << endl;
10 }
11
12 void ch9_2() {
13     using namespace std;
14     string str;
15     while (true) {
16         cout << "enter a line: " << endl;
17         getline(cin, str);
18         if (str == "")
19             break;
20         ch9_2_strcount(str);
21     }
22     cout << "Bye" << endl;
23 }

1 void ch9_3() {
2     using namespace std;
3     int buffer[1000];
4     chaff * arr_chaff = new (buffer)chaff[2];
5     strcpy(arr_chaff[0].dross, "#1"); arr_chaff[0].slag = 123;
6     strcpy(arr_chaff[1].dross, "#2"); arr_chaff[1].slag = 321;
7     for (int i = 0; i < 2; ++ i)
8         cout << "dross: " << arr_chaff[i].dross << " slag: " << arr_chaff[i].slag << endl;
9 }

  1 // chapter 09_sales.h
  2
  3 #ifndef LEARN_CPP_CHAPTER09_SALES_H
  4 #define LEARN_CPP_CHAPTER09_SALES_H
  5
  6 #include <iostream>
  7
  8 namespace SALES
  9 {
 10     const int QUARTERS = 4;
 11     struct Sales {
 12         double sales[QUARTERS];
 13         double average;
 14         double max;
 15         double min;
 16     };
 17     void setSales(Sales &, const double *, int);
 18     void setSales(Sales &);
 19     void showSales(const Sales &);
 20 }
 21
 22
 23
 24 #endif //LEARN_CPP_CHAPTER09_SALES_H
 25
 26
 27
 28
 29
 30
 31
 32 // chapter09_sales.cpp
 33
 34 #include "chapter09_sales.h"
 35
 36 void SALES::setSales(SALES::Sales & s, const double * ar, int n) {
 37     double sum = 0;
 38     int p_max = 0, p_min = 0;
 39     for (int i = 0; i < n; ++ i) {
 40         s.sales[i] = ar[i];
 41         sum += ar[i];
 42         if (ar[i] > ar[p_max])
 43             p_max = i;
 44         if (ar[i] < ar[p_min])
 45             p_min = i;
 46     }
 47     s.average = sum / n;
 48     s.max = ar[p_max];
 49     s.min = ar[p_min];
 50 }
 51
 52 void SALES::setSales(SALES::Sales & s) {
 53     using namespace std;
 54     double sum = 0;
 55     int p_max = 0, p_min = 0, n = 0;
 56     for (int i = 0; i < SALES::QUARTERS; ++ i) {
 57         if (!(cin >> s.sales[i]))
 58             break;
 59         cin.get();
 60         ++ n;
 61         sum += s.sales[i];
 62         if (s.sales[i] > s.sales[p_max])
 63             p_max = i;
 64         if (s.sales[i] < s.sales[p_min])
 65             p_min = i;
 66     }
 67     s.average = sum / n;
 68     s.max = s.sales[p_max];
 69     s.min = s.sales[p_min];
 70 }
 71
 72 void SALES::showSales(const SALES::Sales & s) {
 73     using namespace std;
 74     cout << "sales: ";
 75     for (int i = 0; i < SALES::QUARTERS; ++ i)
 76         if (s.sales[i])
 77             cout << s.sales[i];
 78     cout << endl;
 79     cout << "average: " << s.average << endl;
 80     cout << "max: " << s.max << endl;
 81     cout << "min: " << s.min << endl;
 82 }
 83
 84
 85
 86
 87 // run
 88
 89 void ch9_4() {
 90     using namespace std;
 91     SALES::Sales a;
 92     cout << "set a: " << endl;
 93     SALES::setSales(a);
 94     double s[4]{1.1,2.2,3.3,4.4};
 95     SALES::Sales b;
 96     SALES::setSales(b,s,4);
 97     cout << "a: " << endl;
 98     SALES::showSales(a);
 99     cout << "b: " << endl;
100     SALES::showSales(b);
101 }