自定义比较器，将唯一元素插入到c++中的集合中

我有以下代码片段，用于将元素插入到集合中并检索它们。但正如您从样本输出中看到的，不知何故，学生1的名字（即"stud1"）没有打印出来，即使它是按照他们的到达时间排序的。有人能帮我弄清楚这种方法出了什么问题吗？

学生.h

#ifndef Student_h
#define Student_h
#include "string"
class Student
{
public:
    Student();
    ~Student();
    void setName(const std::string& p_name)     { _name = p_name; }
    void setArrivalTime(const int p_arr_t)      { _arrivalTime = p_arr_t; }
    const std::string& getName() const         { return _name; }
    const int getArrivalTime() const           { return _arrivalTime; }
private:
    std::string _name;
    int _arrivalTime;
};
struct CompareStudByArrivaltime
{
    const bool operator()(const Student* s1, const Student* s2) const;
};
#endif /* Student_h */

学生.cpp

#include <stdio.h>
#include "Student.h"
Student::Student()
{
}
Student::~Student()
{
}
const bool CompareStudByArrivaltime::operator()(const Student* s1, const Student* s2) const
{
    if (s1->getName() == s2->getName())
    {
        return false;
    }
    return (s1->getArrivalTime() <= s2->getArrivalTime());
}

main.cpp

#include <iostream>
#include <set>
#include <map>
#include <vector>
#include "Student.h"
typedef std::vector<Student> StudentsPool;
typedef std::set<Student*, CompareStudByArrivaltime> Students;
typedef std::map<std::string,Students> SchoolStudentsMap;
SchoolStudentsMap g_school_studs;
StudentsPool g_stud_pool;
Student* getStud(const std::string& n)
{
    for(StudentsPool::iterator itr = g_stud_pool.begin(); itr != g_stud_pool.end(); ++itr)
    {
        if (itr->getName() == n)
        {
            return &(*itr);
        }
    }
    return NULL;
}
void initObj()
{
    /** School 1 Record */
    std::string school_name = "school1";
    char c1 [] = {'s','t','u','d','1',''};
    std::string n1(c1);
    //Student* s1 = new Student();
    Student s1;
    s1.setName(n1);
    s1.setArrivalTime(10);
    g_stud_pool.push_back(s1);
    Student* tmp = NULL;
    tmp = getStud("stud1");
    g_school_studs[school_name].insert(tmp);
    char c2 [] = {'s','t','u','d','2',''};
    std::string n2(c2);
    Student s2;
    s2.setName(n2);
    s2.setArrivalTime(2);
    g_stud_pool.push_back(s2);
    tmp = getStud("stud2");
    g_school_studs[school_name].insert(tmp);
    char c3 [] = {'s','t','u','d','3',''};
    std::string n3(c3);
    Student s3;
    s3.setName(n3);
    s3.setArrivalTime(5);
    g_stud_pool.push_back(s3);
    tmp = getStud("stud3");
    g_school_studs[school_name].insert(tmp);
}
void processObj()
{
    for(SchoolStudentsMap::iterator itr = g_school_studs.begin(); itr != g_school_studs.end(); ++itr)
    {
        Students& studs = itr->second;
        for(Students::iterator sitr = studs.begin(); sitr != studs.end(); ++sitr)
        {
            Student* s = (*sitr);
            std::cerr << "Name: " << s->getName() << ", Arr Time: " << s->getArrivalTime() << std::endl;
        }
    }
}
int main(int argc, const char * argv[])
{
    initObj();
    processObj();
    return 0;
}

样本输出

Name: stud2, Arr Time: 2
Name: stud3, Arr Time: 5
Name: , Arr Time: 10