【C++ Primer Plus】编程练习答案——第12章
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1 // chapter12_1_cow.h
2
3
4 #ifndef LEARN_CPP_CHAPTER12_1_COW_H
5 #define LEARN_CPP_CHAPTER12_1_COW_H
6
7 class Cow {
8 private:
9 char name_[20];
10 char * hobby_;
11 double weight_;
12 public:
13 Cow();
14 Cow(const char * name, const char * hobby, double weight);
15 Cow(const Cow & c);
16 ~Cow();
17 Cow & operator=(const Cow & c);
18 void showcow() const;
19 };
20
21
22 #endif //LEARN_CPP_CHAPTER12_1_COW_H
23
24
25 // chapter12_1_cow.cpp
26
27 #include "chapter12_1_cow.h"
28 #include <cstring>
29 #include <iostream>
30
31 Cow::Cow() {
32 name_[0] = '\0';
33 hobby_ = nullptr;
34 weight_ = 0;
35 }
36
37 Cow::Cow(const char * name, const char * hobby, double weight) {
38 strcpy(name_, name);
39 hobby_ = new char[strlen(hobby)];
40 strcpy(hobby_, hobby);
41 weight_ = weight;
42 }
43
44 Cow::Cow(const Cow &c) {
45 strcpy(name_, c.name_);
46 if (!hobby_) delete [] hobby_;
47 hobby_ = new char[strlen(c.hobby_)];
48 strcpy(hobby_, c.hobby_);
49 weight_ = c.weight_;
50 }
51
52 Cow::~Cow() {
53 delete [] hobby_;
54 }
55
56 Cow & Cow::operator=(const Cow & c) {
57 strcpy(name_, c.name_);
58 if (!hobby_) delete [] hobby_;
59 hobby_ = new char[strlen(c.hobby_)];
60 strcpy(hobby_, c.hobby_);
61 weight_ = c.weight_;
62 return *this;
63 }
64
65 void Cow::showcow() const {
66 using namespace std;
67 cout << "name: " << name_ << endl
68 << "hobby: " << hobby_ << endl
69 << "weight: " << weight_ << endl;
70 }
71
72 // run
73
74 void ch12_1() {
75 Cow a("nma", "tennis", 70);
76 Cow b("nmb", "football", 65);
77 a.showcow();
78 b.showcow();
79 b = a;
80 b.showcow();
81 Cow c(a);
82 c.showcow();
83 }
// chapter12_2_string2.h
#ifndef LEARN_CPP_CHAPTER12_2_STRING2_H
#define LEARN_CPP_CHAPTER12_2_STRING2_H
#include <iostream>
using std::istream;
using std::ostream;
class string2 {
private:
char * str;
int len;
static int num_strings;
static const int CINLIM = 80;
public:
string2();
string2(const string2 & s);
string2(const char * s);
~string2();
int length() const {return len;}
int charnum(char ch) const; // d
string2 & stringlow(); // b
string2 & stringup(); // c
string2 & operator=(const string2 & s);
string2 & operator=(const char * s);
char & operator[](int i);
const char & operator[](int i) const;
friend bool operator<(const string2 & s1, const string2 & s2);
friend bool operator>(const string2 & s1, const string2 & s2);
friend bool operator==(const string2 & s1, const string2 & s2);
friend ostream & operator<<(ostream & os, const string2 & s);
friend istream & operator>>(istream & is, string2 & s);
friend string2 & operator+(string2 & s1, const string2 & s2); // a
static int howmany();
};
#endif //LEARN_CPP_CHAPTER12_2_STRING2_H
// chapter12_2_string2.cpp
#include "chapter12_2_string2.h"
#include <cstring>
#include <cctype>
int string2::num_strings = 0;
string2::string2() {
len = 4;
str = new char[1];
str[0] = '\0';
++ num_strings;
}
string2::string2(const string2 &s) {
len = s.length();
str = new char[len + 1];
std::strcpy(str, s.str);
++ num_strings;
}
string2::string2(const char *s) {
len = std::strlen(s);
str = new char[len + 1];
std::strcpy(str, s);
++ num_strings;
}
string2::~string2() {
delete [] str;
-- num_strings;
}
string2 &string2::operator=(const string2 &s) {
if (this == &s)
return *this;
delete [] str;
len = s.length();
str = new char[len + 1];
std::strcpy(str, s.str);
return *this;
}
string2 &string2::operator=(const char *s) {
delete [] str;
len = std::strlen(s);
str = new char[len + 1];
std::strcpy(str, s);
return *this;
}
char &string2::operator[](int i) {
return str[i];
}
const char &string2::operator[](int i) const {
return str[i];
}
int string2::howmany() {
return num_strings;
}
bool operator<(const string2 & s1, const string2 & s2) {
return (std::strcmp(s1.str, s2.str) < 0);
}
bool operator>(const string2 & s1, const string2 & s2) {
return s2 < s1;
}
bool operator==(const string2 & s1, const string2 & s2) {
return (std::strcmp(s1.str, s2.str) == 0);
}
ostream & operator<<(ostream & os, const string2 & s) {
os << s.str;
return os;
}
istream & operator>>(istream & is, string2 & s) {
char temp[string2::CINLIM];
is.get(temp, string2::CINLIM);
if (is)
s = temp;
while (is && is.get() != '\n')
continue;
return is;
}
int string2::charnum(char ch) const {
int i = 0, num = 0;
while (str[i] != '\0') {
if (str[i] == ch)
++ num;
++ i;
}
return num;
}
string2 &string2::stringlow() {
int i = 0;
while (str[i] != '\0') {
if (std::isalpha(str[i]))
str[i] = std::toupper(str[i]);
++ i;
}
return *this;
}
string2 &string2::stringup() {
int i = 0;
while (str[i] != '\0') {
if (std::isalpha(str[i]))
str[i] = std::tolower(str[i]);
++ i;
}
return *this;
}
string2 & operator+(string2 & s1, const string2 & s2) {
char * temp = new char[s1.len];
std::strcpy(temp, s1.str);
delete [] s1.str;
s1.str = new char[s1.len + s2.len + 1];
s1.len += s2.len;
std::strcpy(s1.str, temp);
std::strcat(s1.str, s2.str);
return s1;
}
// run
void ch12_2() {
using namespace std;
string2 s1(" and I am a C++ student.");
string2 s2 = "Please enter your name: ";
string2 s3;
cout << s2;
cin >> s3;
string2 t("My name is ");
s2 = t + s3;
cout << s2 << ".\n";
s2 = s2 + s1;
s2.stringup();
cout << "The string\n" << s2 << "\ncontains " << s2.charnum('A')
<< " 'A' characters in it.\n";
s1 = "red";
string2 rgb[3] = {string2(s1), string2("green"), string2("blue")};
cout << "Enter the name of a primary color for mixing light: ";
string2 ans;
bool success = false;
while (cin >> ans) {
ans.stringlow();
for (int i = 0; i < 3; ++ i) {
if (ans == rgb[i]) {
cout << "That's right!\n";
success = true;
break;
}
}
if (success)
break;
else
cout << "Try again!\n";
}
cout << "Bye\n";
}
1 // chapter12_3_stock.h
2
3
4 void ch12_2() {
5 using namespace std;
6 string2 s1(" and I am a C++ student.");
7 string2 s2 = "Please enter your name: ";
8 string2 s3;
9 cout << s2;
10 cin >> s3;
11 string2 t("My name is ");
12 s2 = t + s3;
13 cout << s2 << ".\n";
14 s2 = s2 + s1;
15 s2.stringup();
16 cout << "The string\n" << s2 << "\ncontains " << s2.charnum('A')
17 << " 'A' characters in it.\n";
18 s1 = "red";
19 string2 rgb[3] = {string2(s1), string2("green"), string2("blue")};
20 cout << "Enter the name of a primary color for mixing light: ";
21 string2 ans;
22 bool success = false;
23 while (cin >> ans) {
24 ans.stringlow();
25 for (int i = 0; i < 3; ++ i) {
26 if (ans == rgb[i]) {
27 cout << "That's right!\n";
28 success = true;
29 break;
30 }
31 }
32 if (success)
33 break;
34 else
35 cout << "Try again!\n";
36 }
37 cout << "Bye\n";
38 }
39
40
41 // chapter12_3_stock.cpp
42
43 #include "chapter12_3_stock.h"
44
45 #include <iostream>
46 #include <cstring>
47
48 stock::stock() {
49 company = new char[8];
50 len = 7;
51 strcpy(company, "no name");
52 shares = 0;
53 share_val = 0.0;
54 total_val = 0.0;
55 }
56
57 stock::stock(const char * co, long n, double pr) {
58 len = strlen(co);
59 company = new char[len + 1];
60 strcpy(company, co);
61 if (n < 0) {
62 std::cout << "Number of shares can't be negative; "
63 << company << " shares set to 0.\n";
64 shares = 0;
65 }
66 else
67 shares = n;
68 share_val = pr;
69 set_tot();
70 }
71
72 stock::~stock() {
73 delete [] company;
74 }
75
76 void stock::buy(long num, double price) {
77 if (num < 0) {
78 std::cout << "Number of shares purchased can't be nagetive. "
79 << "Transaction is aborted.\n";
80 }
81 else {
82 shares += num;
83 share_val = price;
84 set_tot();
85 }
86 }
87
88 void stock::sell(long num, double price) {
89 using std::cout;
90 if (num < 0) {
91 cout << "Number of shares sold can't be negative. "
92 << "Transaction is aborted.\n";
93 }
94 else {
95 shares -= num;
96 share_val = price;
97 set_tot();
98 }
99 }
100
101 void stock::update(double price) {
102 share_val = price;
103 set_tot();
104 }
105
106 void stock::show() const {
107 using std::cout;
108 using std::ios_base;
109 ios_base::fmtflags orig = cout.setf(ios_base::fixed, ios_base::floatfield);
110 std::streamsize prec = cout.precision(3);
111 cout << "Company: " << company
112 << " Shares: " << shares << '\n';
113 cout << "Shares Prices: $" << share_val << '\n';
114 cout.precision(2);
115 cout << "Total Worth: $" << total_val << '\n';
116 cout.setf(orig, ios_base::floatfield);
117 cout.precision(prec);
118 }
119
120 const stock &stock::topval(const stock &s) const {
121 if (s.total_val > total_val)
122 return s;
123 return *this;
124 }
125
126 std::ostream &operator<<(std::ostream & os, const stock & s) {
127 os << "Company: " << s.company
128 << " Shares: " << s.shares << '\n';
129 os << "Shares Prices: $" << s.share_val << '\n';
130 os.precision(2);
131 os << "Total Worth: $" << s.total_val << '\n';
132 }
133
134
135 // run
136
137
138
139 void ch12_3() {
140 using namespace std;
141 const int STKS = 4;
142 stock ss[STKS] = {
143 stock("NanoSmart", 12, 20.0),
144 stock("Boffo Objects", 200, 2.0),
145 stock("Monolithic Obelisks", 130, 3.25),
146 stock("Fleep Enterprises", 60, 6.5)
147 };
148 cout << "Stock holdings: \n";
149 int st;
150 for (st = 0; st < STKS; ++ st)
151 cout << ss[st];
152 const stock * top = &ss[0];
153 for (st = 1; st < STKS; ++ st)
154 top = &top -> topval(ss[st]);
155 cout << "\nMost valuable holding:\n";
156 cout << *top;
157 }
1 // chapter12_4_stack.h
2
3
4 #ifndef LEARN_CPP_CHAPTER12_4_STACK_H
5 #define LEARN_CPP_CHAPTER12_4_STACK_H
6
7 typedef unsigned long Item;
8
9 class Stack {
10 private:
11 enum {MAX = 10};
12 Item * pitems;
13 int size;
14 int top;
15 public:
16 Stack(int n = MAX);
17 Stack(const Stack & st);
18 ~Stack();
19 bool isempty() const;
20 bool isfull() const;
21 bool push(const Item & item);
22 bool pop(Item & item);
23 void show() const;
24 Stack & operator=(const Stack & st);
25 };
26
27
28
29
30 #endif //LEARN_CPP_CHAPTER12_4_STACK_H
31
32 // chapter12_4_stack.cpp
33
34 #include "chapter12_4_stack.h"
35 #include <iostream>
36
37 Stack::Stack(int n) {
38 pitems = new Item[n];
39 size = n;
40 top = 0;
41 }
42
43 Stack::Stack(const Stack &st) {
44 pitems = new Item[st.size];
45 size = st.size;
46 top = st.top;
47 for (int i = 0; i < st.top; ++ i)
48 pitems[i] = st.pitems[i];
49 }
50
51 Stack::~Stack() {
52 delete [] pitems;
53 }
54
55 bool Stack::isempty() const {
56 if (top == 0)
57 return true;
58 return false;
59 }
60
61 bool Stack::isfull() const {
62 if (top == size)
63 return true;
64 return false;
65 }
66
67 bool Stack::push(const Item &item) {
68 if (isfull())
69 return false;
70 pitems[top ++] = item;
71 return true;
72 }
73
74 bool Stack::pop(Item &item) {
75 if (isempty())
76 return false;
77 item = pitems[-- top];
78 return true;
79 }
80
81 Stack &Stack::operator=(const Stack &st) {
82 if (this == &st)
83 return *this;
84 if (pitems)
85 delete [] pitems;
86 pitems = new Item[st.size];
87 size = st.size;
88 top = st.top;
89 for (int i = 0; i < st.top; ++ i)
90 pitems[i] = st.pitems[i];
91 return *this;
92 }
93
94 void Stack::show() const {
95 using namespace std;
96 cout << "Stack: ";
97 for (int i = 0; i < top; ++ i)
98 cout << pitems[i] << " ";
99 cout << endl;
100 }
101
102 // run
103
104 void ch12_4() {
105 Stack s1(15);
106 s1.show();
107 s1.push(1234);s1.push(123);s1.push(12);
108 s1.show();
109 Item t = 0;
110 s1.pop(t);
111 s1.show();
112
113 Stack s2(s1);
114 s2.show();
115 s2.push(12345);
116 s2.show();
117
118 Stack s3 = s1;
119 s3.show();
120 s3.pop(t);
121 s3.show();
122 }
// ch12_5&5 // 待更新
标签：12,const,int,C++,char,Plus,str,return,string2 来源： https://www.cnblogs.com/xushunsdu/p/15337816.html