C++STL map容器这样的写法为啥报错

#include<map>
#include <iostream>
using namespace std;
void printMap(map<int,Person>&m) {
	for (map<int, Person>::iterator it = m.begin(); it != m.end(); it++) {
		cout << "key = " << it->first << " Person value 姓名：" << it->second.m_Name << "Person value 年龄：" << it->second.m_Age << endl;
	}
}
class Person {
public:
	Person(string name, int age) {
		this->m_Name = name;
		this->m_Age = age;
	}
	string m_Name;
	int m_Age;
};

void test01() {
	map<int, Person>m;
	Person p1("刘备", 20);
	Person p2("张飞", 21);
	Person p3("关羽", 25);
	Person p4("赵云", 26);
	m.insert(make_pair(1, p1));

}
int main()
{
	test01();
	system("pause");
	return 0;
}

1，#include<string>

2，class Person定义放到void printMap(map<int,Person>&m) 前

没有什么问题啊。