map 运算符重载

#include <stdio.h>
#include <map>
#include <string>
#include <algorithm>
#include <iostream>

using namespace std;

typedef struct studentinfo
{
    int ID;
    string strName;
    bool operator < (studentinfo const & A) const
    {
        if (ID < A.ID )
            return true;
        if (ID == A.ID)
            return strName.compare(A.strName) < 0;
        return false;
    }
}stu;

int main( )
{
   //用学生信息映射分数
    map<stu,int>mp;
    studentinfo st;
    st.ID = 1;
    st.strName = "peter";
    mp.insert(pair<stu,int>(st,90));
    st.ID = 1;
    st.strName = "jack";
    mp.insert(pair<stu,int>(st,91));
    map<stu,int>::iterator iter;
    for(iter = mp.begin( ); iter != mp.end( ); iter++)
        cout<<iter->first.ID<<" "<<iter->second<<" "<<iter->first.strName<<endl;
}