std::set自定义比较函数

//set with user define comparer#include<set>#include<algorithm>#include<string>#include<functional>#include<iostream>using namespace std;struct Person{int age;string name;Person(const int a=0,const string &n="nobody"):age(a),name(n){}bool operator < (const Person &rhs) const { return this->age < rhs.age; }bool operator > (const Person &rhs) const { return this->age > rhs.age; }};bool Greater(const Person &a, const Person &b){return a.age > b.age;}struct LesserAge: public binary_function<Person,Person,bool>{inline bool operator()(const Person &a, const Person &b){return a.age < b.age;}};int main(){set<Person> s0;s0.insert(Person(24,"Calvin"));s0.insert(Person(32,"Benny"));s0.insert(Person(30,"Alice"));s0.insert(Person(28,"Alison"));for(set<Person>::iterator it=s0.begin(); it!=s0.end(); ++it) cout << it->age << "," << it->name << endl;cout << "========" << endl;set<Person,std::greater<Person> > s1;s1.insert(Person(24,"Calvin"));s1.insert(Person(32,"Benny"));s1.insert(Person(30,"Alice"));s1.insert(Person(28,"Alison"));for(set<Person>::iterator it=s1.begin(); it!=s1.end(); ++it) cout << it->age << "," << it->name << endl;cout << "========" << endl;set<Person,LesserAge> s2;s2.insert(Person(24,"Calvin"));s2.insert(Person(32,"Benny"));s2.insert(Person(30,"Alice"));s2.insert(Person(28,"Alison"));for(set<Person>::iterator it=s2.begin(); it!=s2.end(); ++it) cout << it->age << "," << it->name << endl;return 0;}