【C++ Primer Plus习题】16.10

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问题:

解答:

#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <memory>
using namespace std;struct Review
{string title;int rating;int price;
};bool operator<(const shared_ptr<Review>& p1, const shared_ptr<Review>& p2);
bool FillReview(Review& rr);
void ShowReview(const shared_ptr<Review>& p);
bool worseThan(const shared_ptr<Review>& p1, const shared_ptr<Review>& p2);
bool expenThan(const shared_ptr<Review>& p1, const shared_ptr<Review>& p2);int main()
{vector<shared_ptr<Review>>books;Review temp;while (FillReview(temp)){shared_ptr<Review>pd(new Review(temp));books.push_back(pd);}if (books.size() > 0){cout << "Choose the way to sort: "<< "r:rate, s: rate r, p:price, d:price, d:price r, q:quit\n";char choice;while (cin >> choice && choice != 'q'){switch (choice){case 'r':sort(books.begin(), books.end(), worseThan);break;case 's':sort(books.rbegin(), books.rend(), worseThan);break;case 'p':sort(books.begin(), books.end(), expenThan);break;case 'd':sort(books.rbegin(), books.rend(), expenThan);break;default:break;}for_each(books.begin(), books.end(), ShowReview);cout<<"Please choose the way to sort: "<< "r:rate, s: rate r, p:price, d:price, d:price r, q:quit\n";}}return 0;
}bool operator<(const shared_ptr<Review>& p1, const shared_ptr<Review>& p2)
{if (p1->title < p2->title)return true;else if (p1->title == p2->title && p1->rating < p2->rating)return true;elsereturn false;
}
bool FillReview(Review& rr)
{cout << "Enter book title (quit to quit): ";getline(cin, rr.title);if (rr.title == "quit" || rr.title == "")return false;cout << "Enter book rating: ";cin >> rr.rating;if (!cin)return false;cout << "Enter book price: ";cin >> rr.price;if (!cin)return false;while (cin.get() != '\n'){continue;}return true;
}
void ShowReview(const shared_ptr<Review>& p)
{cout << p->rating << "\t" << p->title << "\t" << p->price << endl;
}
bool  worseThan(const shared_ptr<Review>& p1, const shared_ptr<Review>& p2)
{if (p1->rating < p2->rating)return true;elsereturn false;
}
bool expenThan(const shared_ptr<Review>& p1, const shared_ptr<Review>& p2)
{if (p1->price < p2->price)return true;elsereturn false;
}