这个程序有什么用呢？谁能告诉我呢？

 

#include<iostream>

using namespace std;

class PhoneNumber

{

   friend ostream & operator<<(ostream &,const PhoneNumber &);

   friend istream & operator>>(istream &,PhoneNumber &);

private:

   char areacode[4];

   char exchange[4];

   char line[5];

};

ostream & operator<<(ostream & output,const PhoneNumber& num)

{

   output<<"("<<num.areacode<<")"<<num.exchange<<"-"<<num.line<<endl;

    return output;

}

istream & operator>>(istream & input,PhoneNumber& num)

{

   input.ignore();

   input.get(num.areacode,4);

   input.ignore(2);

   input.get(num.exchange,4);

   input.ignore();

   input.get(num.line,5);

   return input;

}

int main()

{

   PhoneNumber phone;

   cout<<"enter a PhoneNumber is the"<<"form(123)456-7890/n";

   cin>>phone;

   cout<<"the PhoneNumber entered was:/n"<<phone<<endl;

   system("pause");

   return 0;

}