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;
}