C++ map 自定义比较函数

#include <iostream>
#include <map>

using namespace std;

void fun(int a[]){
    a[0] = 12;
}

struct compare
{
    bool operator()(const char * s1, const char * s2) const
    {
        return strcmp(s1, s2) < 0;
    }
};
int main(){
    map<char*, char*, compare> student;

    char id1[11] = "1395682451";
    char name1[18] = "xiaoming";
    student.insert(pair<char*, char*>(id1, name1));
    cout << student[id1] << endl;

    char id2[11] = "1395682451";
    char name2[18] = "lisi";
    student.insert(pair<char*, char*>(id2, name2));
    cout << student[id2] << endl;

    student[id1] = name2;
    cout << student[id2] << endl;

    map<char*, char*> teacher;
    teacher.insert(pair<char*, char*>(id1, name1));
    teacher.insert(pair<char*, char*>(id2, name2));
    cout << "teacher 1 is: " << teacher[id1] << endl;
    cout << "teacher 2 is: " << teacher[id2] << endl;

    int b[2] = { 1, 2 };
    fun(b);
    cout << b[0] << endl;


    return 0;
}