【C++ Primer Plus】编程练习答案——第12章

1 // chapter12_1_cow.h 234 #ifndef LEARN_CPP_CHAPTER12_1_COW_H 5 #define LEARN_CPP_CHAPTER12_1_COW_H 67 class Cow { 8 private: 9char name_[20];10char * hobby_;11double weight_;12 public:13Cow();14Cow(const char * name, const char * hobby, double weight);15Cow(const Cow & c);16~Cow();17Cow & operator=(const Cow & c);18void showcow() const;19 };20 21 22 #endif //LEARN_CPP_CHAPTER12_1_COW_H23 24 25 // chapter12_1_cow.cpp26 27 #include "chapter12_1_cow.h"28 #include <cstring>29 #include <iostream>30 31 Cow::Cow() {32name_[0] = '\0';33hobby_ = nullptr;34weight_ = 0;35 }36 37 Cow::Cow(const char * name, const char * hobby, double weight) {38strcpy(name_, name);39hobby_ = new char[strlen(hobby)];40strcpy(hobby_, hobby);41weight_ = weight;42 }43 44 Cow::Cow(const Cow &c) {45strcpy(name_, c.name_);46if (!hobby_) delete [] hobby_;47hobby_ = new char[strlen(c.hobby_)];48strcpy(hobby_, c.hobby_);49weight_ = c.weight_;50 }51 52 Cow::~Cow() {53delete [] hobby_;54 }55 56 Cow & Cow::operator=(const Cow & c) {57strcpy(name_, c.name_);58if (!hobby_) delete [] hobby_;59hobby_ = new char[strlen(c.hobby_)];60strcpy(hobby_, c.hobby_);61weight_ = c.weight_;62return *this;63 }64 65 void Cow::showcow() const {66using namespace std;67cout << "name: " << name_ << endl68<< "hobby: " << hobby_ << endl69<< "weight: " << weight_ << endl;70 }71 72 // run73 74 void ch12_1() {75Cow a("nma", "tennis", 70);76Cow b("nmb", "football", 65);77a.showcow();78b.showcow();79b = a;80b.showcow();81Cow c(a);82c.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; // dstring2 & stringlow(); // bstring2 & stringup(); // cstring2 & 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); // astatic 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;}// runvoid 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;elsecout << "Try again!\n";}cout << "Bye\n";}1 // chapter12_3_stock.h234 void ch12_2() {5using namespace std;6string2 s1(" and I am a C++ student.");7string2 s2 = "Please enter your name: ";8string2 s3;9cout << s2; 10cin >> s3; 11string2 t("My name is "); 12s2 = t + s3; 13cout << s2 << ".\n"; 14s2 = s2 + s1; 15s2.stringup(); 16cout << "The string\n" << s2 << "\ncontains " << s2.charnum('A') 17<< " 'A' characters in it.\n"; 18s1 = "red"; 19string2 rgb[3] = {string2(s1), string2("green"), string2("blue")}; 20cout << "Enter the name of a primary color for mixing light: "; 21string2 ans; 22bool success = false; 23while (cin >> ans) { 24ans.stringlow(); 25for (int i = 0; i < 3; ++ i) { 26if (ans == rgb[i]) { 27cout << "That's right!\n"; 28success = true; 29break; 30} 31} 32if (success) 33break; 34else 35cout << "Try again!\n"; 36} 37cout << "Bye\n"; 38 } 394041 // chapter12_3_stock.cpp 4243 #include "chapter12_3_stock.h" 4445 #include <iostream> 46 #include <cstring> 4748 stock::stock() { 49company = new char[8]; 50len = 7; 51strcpy(company, "no name"); 52shares = 0; 53share_val = 0.0; 54total_val = 0.0; 55 } 5657 stock::stock(const char * co, long n, double pr) { 58len = strlen(co); 59company = new char[len + 1]; 60strcpy(company, co); 61if (n < 0) { 62std::cout << "Number of shares can't be negative; " 63<< company << " shares set to 0.\n"; 64shares = 0; 65} 66else 67shares = n; 68share_val = pr; 69set_tot(); 70 } 7172 stock::~stock() { 73delete [] company; 74 } 7576 void stock::buy(long num, double price) { 77if (num < 0) { 78std::cout << "Number of shares purchased can't be nagetive. " 79<< "Transaction is aborted.\n"; 80} 81else { 82shares += num; 83share_val = price; 84set_tot(); 85} 86 } 8788 void stock::sell(long num, double price) { 89using std::cout; 90if (num < 0) { 91cout << "Number of shares sold can't be negative. " 92<< "Transaction is aborted.\n"; 93} 94else { 95shares -= num; 96share_val = price; 97set_tot(); 98} 99 }100 101 void stock::update(double price) {102share_val = price;103set_tot();104 }105 106 void stock::show() const {107using std::cout;108using std::ios_base;109ios_base::fmtflags orig = cout.setf(ios_base::fixed, ios_base::floatfield);110std::streamsizeprec = cout.precision(3);111cout << "Company: " << company112<< "Shares: " << shares << '\n';113cout << "Shares Prices: $" << share_val << '\n';114cout.precision(2);115cout << "Total Worth: $" << total_val << '\n';116cout.setf(orig, ios_base::floatfield);117cout.precision(prec);118 }119 120 const stock &stock::topval(const stock &s) const {121if (s.total_val > total_val)122return s;123return *this;124 }125 126 std::ostream &operator<<(std::ostream & os, const stock & s) {127os << "Company: " << s.company128<< "Shares: " << s.shares << '\n';129os << "Shares Prices: $" << s.share_val << '\n';130os.precision(2);131os << "Total Worth: $" << s.total_val << '\n';132 }133 134 135 // run136 137 138 139 void ch12_3() {140using namespace std;141const int STKS = 4;142stock ss[STKS] = {143stock("NanoSmart", 12, 20.0),144stock("Boffo Objects", 200, 2.0),145stock("Monolithic Obelisks", 130, 3.25),146stock("Fleep Enterprises", 60, 6.5)147};148cout << "Stock holdings: \n";149int st;150for (st = 0; st < STKS; ++ st)151cout << ss[st];152const stock * top = &ss[0];153for (st = 1; st < STKS; ++ st)154top = &top -> topval(ss[st]);155cout << "\nMost valuable holding:\n";156cout << *top;157 }1 // chapter12_4_stack.h234 #ifndef LEARN_CPP_CHAPTER12_4_STACK_H5 #define LEARN_CPP_CHAPTER12_4_STACK_H67 typedef unsigned long Item;89 class Stack { 10 private: 11enum {MAX = 10}; 12Item * pitems; 13int size; 14int top; 15 public: 16Stack(int n = MAX); 17Stack(const Stack & st); 18~Stack(); 19bool isempty() const; 20bool isfull() const; 21bool push(const Item & item); 22bool pop(Item & item); 23void show() const; 24Stack & operator=(const Stack & st); 25 }; 2627282930 #endif //LEARN_CPP_CHAPTER12_4_STACK_H 3132 // chapter12_4_stack.cpp 3334 #include "chapter12_4_stack.h" 35 #include <iostream> 3637 Stack::Stack(int n) { 38pitems = new Item[n]; 39size = n; 40top = 0; 41 } 4243 Stack::Stack(const Stack &st) { 44pitems = new Item[st.size]; 45size = st.size; 46top = st.top; 47for (int i = 0; i < st.top; ++ i) 48pitems[i] = st.pitems[i]; 49 } 5051 Stack::~Stack() { 52delete [] pitems; 53 } 5455 bool Stack::isempty() const { 56if (top == 0) 57return true; 58return false; 59 } 6061 bool Stack::isfull() const { 62if (top == size) 63return true; 64return false; 65 } 6667 bool Stack::push(const Item &item) { 68if (isfull()) 69return false; 70pitems[top ++] = item; 71return true; 72 } 7374 bool Stack::pop(Item &item) { 75if (isempty()) 76return false; 77item = pitems[-- top]; 78return true; 79 } 8081 Stack &Stack::operator=(const Stack &st) { 82if (this == &st) 83return *this; 84if (pitems) 85delete [] pitems; 86pitems = new Item[st.size]; 87size = st.size; 88top = st.top; 89for (int i = 0; i < st.top; ++ i) 90pitems[i] = st.pitems[i]; 91return *this; 92 } 9394 void Stack::show() const { 95using namespace std; 96cout << "Stack: "; 97for (int i = 0; i < top; ++ i) 98cout << pitems[i] << " "; 99cout << endl;100 }101 102 // run103 104 void ch12_4() {105Stack s1(15);106s1.show();107s1.push(1234);s1.push(123);s1.push(12);108s1.show();109Item t = 0;110s1.pop(t);111s1.show();112 113Stack s2(s1);114s2.show();115s2.push(12345);116s2.show();117 118Stack s3 = s1;119s3.show();120s3.pop(t);121s3.show();122 }【【C++ Primer Plus】编程练习答案——第12章】// ch12_5&6// 待更新欢迎大家一起交流。
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