练习14.6
1 #include2 #include 3 #include 4 #include 5 #include 6 #include 7 8 using namespace std; 9 10 class Sales_data {11 friend istream& operator >> (istream& is, Sales_data &s);12 friend ostream& operator<<(ostream& os, Sales_data s);13 public:14 Sales_data() : bookNo("") {}15 Sales_data(string s, unsigned us, double up) : bookNo(s), units_sold(us), units_price(up) {}16 Sales_data operator+(const Sales_data& s);17 Sales_data& operator+=(const Sales_data& s);18 private:19 string bookNo;20 unsigned units_sold = 0;21 double units_price = 0;22 };23 24 istream& operator >> (istream& is, Sales_data &s);25 ostream& operator<<(ostream& os, Sales_data s);26 27 int main()28 {29 Sales_data s1;30 Sales_data s2("C++ primer", 10, 128.2);31 cout << s2 << endl;32 s1 = s2;33 cout << s1 << endl;34 cout << s1 + s2 << endl;35 s1 += s2;36 cout << s1 << endl;37 cin >> s1;38 cout << s1;39 cout << s1 + s2 << endl;40 system("pause");41 return 0;42 }43 44 istream & operator >> (istream & is, Sales_data &s)45 {46 is >> s.bookNo >> s.units_sold >> s.units_price;47 return is;48 // TODO: 在此处插入 return 语句49 }50 51 ostream & operator<<(ostream & os, Sales_data s)52 {53 os << s.bookNo << " " << s.units_sold << " " << s.units_price;54 return os;55 // TODO: 在此处插入 return 语句56 }57 58 Sales_data & Sales_data::operator+=(const Sales_data & s)59 {60 if (bookNo == s.bookNo)61 {62 units_sold = units_sold + s.units_sold;63 return *this;64 }65 else66 {67 cout << "can not add" << endl;68 return *this;69 }70 // TODO: 在此处插入 return 语句71 }72 73 Sales_data Sales_data::operator+(const Sales_data & s)74 {75 if (bookNo == s.bookNo)76 {77 Sales_data ss;78 ss.bookNo = bookNo;79 ss.units_price = units_price;80 ss.units_sold = units_sold + s.units_sold;81 return ss;82 }83 else84 {85 cout << "error" << endl;86 return *this;87 }88 // TODO: 在此处插入 return 语句89 }
练习14.7
1 #include2 #include 3 #include 4 #include 5 #include 6 7 using namespace std; 8 9 class String {10 friend ostream &operator<<(ostream &os, String &s);11 public:12 String() : element(nullptr), first_free(nullptr) {}13 String(char *);14 private:15 static allocator alloc;16 char *element;17 char *first_free;18 };19 allocator String::alloc;20 ostream &operator<<(ostream &os, String &s);21 22 int main()23 {24 String s1;25 String s2("hello");26 String s3("hello world");27 cout << s1;28 cout << s2;29 cout << s3;30 system("pause");31 return 0;32 }33 34 String::String(char *s)35 {36 int i = 0;37 while (s[i] != '\0')38 ++i;39 auto newloc = alloc.allocate(i);40 auto dest = newloc;41 for (auto count = 0; count != i;++count)42 alloc.construct(dest++, s[count]);43 element = newloc;44 first_free = dest;45 }46 47 ostream & operator<<(ostream &os, String &s)48 {49 while (s.element != s.first_free)50 {51 os << *(s.element);52 s.element++;53 }54 cout << endl;55 return os;56 // TODO: 在此处插入 return 语句57 }
练习14.8
类似上题，很简单，细心注意一下就行了