C++primer 7.1.2节练习
练习7,2
1 #include <iostream> 2 #include <string> 3 using namespace std; 4 5 struct Sales_data { 6 string bookNo; 7 unsigned units_sold; 8 double price = 0.0; 9 double revenue = 0.0; 10 Sales_data &combine(const Sales_data&); 11 string isbn() const {return bookNo;} 12 }; 13 14 Sales_data & Sales_data::combine(const Sales_data &rhs) 15 { 16 units_sold += rhs.units_sold; 17 revenue += rhs.revenue; 18 return *this; 19 } 20 21 int main() 22 { 23 Sales_data item1, item2; 24 double totalRevenue = 0; 25 double totalSold = 0; 26 int counter = 1; 27 if (cin >> item1.bookNo >> item1.units_sold >> item1.price) 28 { 29 item1.revenue = item1.price * item1.units_sold; 30 while (cin >> item2.bookNo >> item2.units_sold >> item2.price) { 31 item2.revenue = item2.price * item2.units_sold; 32 if (item1.bookNo == item2.bookNo) { 33 item1.combine(item2); 34 ++counter; 35 } 36 else { 37 cout << item1.isbn() << " " << item1.units_sold << " " << item1.revenue << " Times:" << counter << endl; 38 item1.bookNo = item2.bookNo; 39 item1.units_sold = item2.units_sold; 40 item1.revenue = item2.revenue; 41 counter = 1; 42 } 43 } 44 cout << item1.bookNo << " " << item1.units_sold << " " << item1.revenue << " Times:" << counter << std::endl; 45 } 46 return 0; 47 }
练习7.3
见上面代码
练习7.4
1 struct person { 2 string person_name;//人员姓名 3 string person_add;//人员居住地址 4 };
练习7.5
1 string backName() const { return person_name; } 2 string backAddr() const { return person_addr; }
应该是const，在这两个函数体内不会改变this所指的对象，所以把this设置为指向常量的指针有助于提高函数的灵活性。
