Primer plus C++ 第十六章 标准模板库_STL排序函数

/*
*STL中排序相关函数:
* 1)operator<()为全排序；
* 2）WorseThan()为完整弱排序；
*/
#include 
#include
#include
#include
// 结构体在c++中和类一样对待,他们唯一的区别，就是缺省情况下，struct中的所有成员都是public的，class中的所有成员都是private的
struct Review {
	std::string title;
	int rating;
};
bool operator<(const Review & r1, const Review & r2);
bool worseThan(const Review & r1, const Review & r2);
bool FillReview(Review & rr);
void ShowReview(const Review & rr);
int main() {
	using namespace std;
	vector books;
	Review temp;
	while (FillReview(temp))
		books.push_back(temp);
	cout << "Thank you. You entered the following" << books.size()
		<< "ratings: \n" << "Rating \t Book\n";

	for_each(books.begin(), books.end(), ShowReview);
	sort(books.begin(), books.end());
	cout << "Sorted by title: \n Rating \t book \ n";
	for_each(books.begin(), books.end(), ShowReview);
	sort(books.begin(), books.end(), worseThan);
	cout << "Sorted by rating: \n Rating \t  Book \n";
	for_each(books.begin(), books.end(), ShowReview);
	// Random_shuffle()接收两个指定区间的迭代器参数，并随机排列该区域中的元素；
	random_shuffle(books.begin(), books.end());
	cout << "After shuffling: \n Rating \t Book \n";
	for_each(books.begin(), books.end(), ShowReview);
	cout << "Bye. \n";
	return 0;
}
bool operator<(const Review & r1, const Review & r2) {
	if (r1.title < r2.title)
		return true;
	else if (r1.title == r2.title && r1.rating < r2.rating)
		return true;
	else
		return false;
}
bool worseThan(const Review & r1, const Review & r2) {
	if (r1.rating < r2.rating)
		return true;
	else
		return false;
}
bool FillReview(Review & rr) {
	std::cout << "Enter book title (quit to quit): ";
	std::getline(std::cin, rr.title);
	if (rr.title == "quit")
		return false;
	std::cout << "Enter book rating: ";
	std::cin >> rr.rating;
	if (!std::cin)
		return false;
	std::cin.get();
	return true;
}
void ShowReview(const Review & rr)
{
	std::cout << rr.rating << "\t" << rr.title << std::endl;
}