c++ - Making a custom class ostream outputable? -

i'm trying print balance checking , savings account. know can't return value using void function, in way can show balances both accounts?

#ifndef account_h #define account_h  // account.h // 4/8/14 // description  class account { private:     double balance;     double interest_rate; // example, interest_rate = 6 means 6% public:     account();     account(double);     void deposit(double);     bool withdraw(double); // returns true if there enough money, otherwise false     double query();     void set_interest_rate(double rate);     double get_interest_rate();     void add_interest(); };  #endif   // bank.cpp // 4/12/14 // description  #include <iostream> #include <string> #include "bank.h"  using namespace std;  bank::bank(): checking(0), savings(0) { }  bank::bank(double checking_amount, double savings_amount): checking(checking_amount), savings(savings_amount){;      checking = account(checking_amount);     savings = account(savings_amount); }  void bank::deposit(double amount, string account) {     if (account == "s") {         savings.deposit(amount);     } if (account == "c") {         checking.deposit(amount);     } }  void bank::withdraw(double amount, string account) {     if (account == "s") {         savings.withdraw(amount);     } if (account == "c") {         checking.withdraw(amount);     } }  void bank::transfer(double amount, string account) {     if (account == "s") {         savings.deposit(amount);         checking.withdraw(amount);     } if (account == "c") {         checking.deposit(amount);         savings.withdraw(amount);     } }  void bank::print_balances() {     cout << savings << endl;     cout << checking << endl;  }  #ifndef bank_h #define bank_h  // bank.h // 4/12/14 // description  #include <string>  #include "account.h"  using namespace std;  class bank { private:     account checking;     account savings; public:     bank();     bank(double savings_amount, double checking_amount);     void deposit(double amount, string account);     void withdraw(double amount, string account);     void transfer(double amount, string account);     void print_balances(); };  #endif 

i'm getting 2 errors under void bank::print_balances(). says:

"no match 'operator<<' in 'std::cout << ((bank*)this) ->bank::savings'" 

i reading lot it, learned since "checking" , "savings" account type, won't work. previous project similar, , had "double" types instead able return value.

sorry if format wrong. first time posting on site.

you need overload operator<< custom class account in order able cout<< objects.

class account {     ... public:     friend ostream& operator<<(ostream &os, const account &dt);     ... };  ostream& operator<<(ostream &os, const account &dt) {     os << dt.balance; // print balance     return os; } 

to read on, check out overloading i/o operators.