c++ primer plus 习题答案(3)

p296.3

 1 #include<iostream>

 2 #include<cstdlib>

 3 #include<string>

 4 #include<cstring>

 5 #include<new>

 6 using namespace std;

 7 struct chaff

 8 {

 9     char dross[20];

10     int slag;

11 };

12 void setarray(chaff *pt);

13 void showarray(chaff *pt);

14 

15 int main(){

16     char buffer[40];

17     chaff ar[2], *pt;

18     pt = new(buffer)chaff[2];

19     setarray(pt);

20     showarray(pt);

21     system("pause");

22     return 0;

23 }

24 

25 void setarray(chaff *pt){

26     int i;

27     char adross[20], pdross[20], ch;

28     cout << "enter a line\n";

29     cin.get(adross, 20);

30     while (cin){

31         cin.get(ch);

32         while (ch != '\n')

33             cin.get(ch);

34         break;

35     }

36     strcpy(pt->dross, adross);

37     cout << "enter another line\n";

38     cin.get(pdross, 20);

39     while (cin){

40         cin.get(ch);

41         while (ch != '\n')

42             cin.get(ch);

43         break;

44     }

45     strcpy((pt + 1)->dross, pdross);

46     cout << "enter two integer\n";

47     cin >> pt->slag;

48     cin >> (pt + 1)->slag;

49     cin.get();                    

50 }

51 

52 void showarray(chaff *pt){

53     cout << pt->dross << " " <<

54         pt->slag << endl <<

55         (pt + 1)->dross << " " <<

56         (pt + 1)->slag << endl;

57 }

p296.4

 1 sales.cpp

 2 

 3 #include<iostream>

 4 #include"sales.h"

 5 using namespace std;

 6 

 7 void SALES::setsales(Sales &s, const double ar[], int n){

 8     int num, i, sum=0;

 9     if (n <= QUARTERS)

10         num = n;

11     else num = QUARTERS;

12     for (i = 0; i < num; i++){

13         s.sales[i] = ar[i];

14         sum += s.sales[i];

15     }

16     s.average = sum / num;

17     s.max = s.sales[0];

18     s.min = s.sales[0];

19     for (i = 1; i < num; i++){

20         if (s.max < s.sales[i])

21             s.max = s.sales[i];

22         if (s.min>s.sales[i])

23             s.min = s.sales[i];

24     }

25 }

26 

27 void SALES::setsales(Sales &s){

28     cout << "enter double into an array\n";

29     int i;

30     double sum = 0;

31     for (i = 0; i < QUARTERS; i++){

32         cin >> s.sales[i];

33         sum += s.sales[i];

34     }

35     s.average = sum / QUARTERS;

36     s.max = s.sales[0];

37     s.min = s.sales[0];

38     for (i = 1; i < QUARTERS; i++){

39         if (s.max < s.sales[i])

40             s.max = s.sales[i];

41         if (s.min>s.sales[i])

42             s.min = s.sales[i];

43     }

44 }

45 

46 void SALES::showsales(const Sales & s){

47     for (int i = 0; i < QUARTERS; i++)

48         cout << s.sales[i] << " ";

49     cout << "average is " << s.average << endl <<

50         "max is " << s.max << endl <<

51         "min is " << s.min << endl;

52 }

53 

54 驱动程序

55 

56 #include<iostream>

57 #include<cstdlib>

58 #include<string>

59 #include<cstring>

60 #include"sales.h"

61 using namespace std;

62 

63 int main(){

64     cout << "enter a number you want to fill the array\n";

65     int n, i;

66     cin >> n;

67     double *ar = new double[n+1];

68     cout << "enter an double array\n";

69     for (i = 0; i < n; i++)

70         cin >> ar[i];

71     SALES::Sales ex1, ex2;

72     SALES::setsales(ex1, ar, n);

73     SALES::setsales(ex2);

74     SALES::showsales(ex1);

75     SALES::showsales(ex2);

76     delete[]ar;

77     system("pause");

78     return 0;

79 }

80 

81 

82 头文件

83 

84 namespace SALES

85 {

86     const int QUARTERS = 4;

87     struct Sales{

88         double sales[QUARTERS];

89         double average;

90         double max;

91         double min;

92     };

93     void setsales(Sales &s, const double ar[], int n);

94     void setsales(Sales &s);

95     void showsales(const Sales&s);

96 }

p332.1

 1 #include<iostream>

 2 #include<cstdlib>

 3 #include<cstring>

 4 using namespace std;

 5 

 6 class Bankacount{

 7     char name[30];

 8     char num[20];

 9     double deposit;

10 public:

11     Bankacount(char *pt="nobody", char *ar="0", double balance=0.0);

12     ~Bankacount();

13     void storage(double ct);

14     void withdraw(double ct);

15     void show()const;

16 };

17 

18 Bankacount::Bankacount(char *pt, char *ar, double balance)

19 {

20     strncpy(name, pt, 29);

21     name[30] = '\0';

22     strncpy(num, ar, 19);

23     num[20] = '\0';

24     deposit = balance;

25 }

26 

27 Bankacount::~Bankacount(){

28 

29 }

30 

31 void Bankacount::storage(double ct){

32     if (ct < 0)

33         cout << "the deposit must be positive\n";

34     else deposit += ct;

35 }

36 

37 void Bankacount::withdraw(double ct){

38     if (ct<0)

39         cout << "the deposit must be positive\n";

40     else deposit -= ct;

41 }

42 

43 void Bankacount::show()const{

44     cout << "name is " << name << endl

45         << "number is " << num << endl

46         << "deposit now is " << deposit << endl;

47 }

48 

49 

50 int main(){

51     Bankacount acount1("GE", "asdf", 0.0);

52     Bankacount acount2;

53     Bankacount acount3 = Bankacount("DELL", "34WE", 2.3);

54     acount1.show();

55     acount2.show();

56     acount3.show();

57     acount1.storage(4.5);

58     acount2.withdraw(2.7);

59     acount1.show();

60     acount2.show();

61 

62     system("pause");

63     return 0;

64 }