仿函数1-当排序规则

#include <string>#include <set>#include <algorithm>using namespace std;class Person{public:Person(const std::string& first_name, const std::string& last_name) :first_name_(first_name), last_name_(last_name){}std::string firstname()  const { return first_name_;}std::string lastname() const {return last_name_;}private:std::string first_name_;std::string last_name_;};class PersonSortCriterion{public:bool operator()(const Person& lhs, const Person& rhs) {return lhs.lastname() < rhs.lastname() || (!(lhs.lastname() < rhs.lastname()) && lhs.firstname() < rhs.firstname());}};int _tmain(int argc, _TCHAR* argv[]){typedef std::set<Person, PersonSortCriterion> PersonSet;PersonSet ps;ps.insert(Person("ketty","Yang"));ps.insert(Person("ketty", "Xang"));ps.insert(Person("ketty", "Wang"));return 0;}