【c++ primer, 5e】访问控制与封装

#include <iostream>
#include <string>
using namespace std;

// Person.h
class Person {
friend istream &read(istream &is, Person &p);
public:
    Person() = default;
    Person(const string &name): name(name) {}
    Person(const string &name, const string &address): name(name), address(address) {}
    Person(istream&);
    string getName() const { return name; }
    string getAddress() const  { return address; }
private:
    string name;
    string address;
};
istream &read(istream&, Person&);
ostream &print(ostream&, const Person&);

// Person.cpp
istream &read(istream &is, Person &p)
{
    is >> p.name >> p.address;
    return is;
}
ostream &print(ostream &os, const Person &p)
{
    os << p.getName() << " " << p.getAddress();
    return os;
}
Person::Person(istream &is)
{
    read(is, *this);
}

// main.cpp
int main()
{
    Person p1;
    Person p2("xklf");
    Person p3("llyy", "china");
    Person p4(cin);
    print(cout, p1) << endl;
    print(cout, p2) << endl;
    print(cout, p3) << endl;
    print(cout, p4) << endl;
    return 0;
}