Saving an object to a file

What is wrong with this code? I keep getting errors saying

error C2679: binary '<<' : no operator defined which takes a right-hand operand of type 'class Account' (or there is no acceptable conversion)

any help would be greatly appreciated.

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

class Account {
protected:
float Balance;
char Accountno[5];
public:
Account(char id[5], float initialbal);
~Account();

};
Account::Account(char id[5], float initialbal)
{
strcpy(Accountno, id);
Balance = initialbal;
}

Account::~Account(){}

void main()
{
Account acc1("1234", 500);
Account acc2("2345", 1000);

fstream in_out ("acc.txt", ios::in|ios::out);
if (in_out.fail() )
{
cerr << "error opening acc.txt" <<endl;
return ;
}

in_out << acc1 << acc2 ;

in_out.seekg ( 0 );

in_out >> acc1 >> acc2 ;
cout << acc1 << acc2 ;
}

Define an overloaded operator:

Code:

---

friend ostream& operator<<(ostream& os, Account& rhs)
{
  os << rhs.<blah> << <etc>;
  return os;
}

---

Just os << each of the members that you want to write.

Z.