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I keep getting the following errors

Error (active) E0349 no operator "<<" matches these operands Error C2678 binary '<<': no operator found which takes a left-hand operand of type 'std::ostream' (or there is no acceptable conversion)

I know the issue is that there's something going wrong or missing when I try to overload the operator and I think its something small at this point, but I have no idea anymore. Any help would be appreciated.

.h file

#include <iostream> #include <string> #include <ostream> using namespace std; #ifndef ACCOUNT_H #define ACCOUNT_H class account { private: int acct_ID; string acct_name; float acct_balance; static int next_id; public: account(); account(account& rhs); ~account(); account(int acct_ID, string acct_name, float acct_balance); void set_ID(int acct_ID); int get_ID()const; void set_name(string acct_name); void input(); void set_balance(float acct_balance); ostream& display(ostream& stream); }; ostream& operator<<(ostream& stream, account& Account); //!!!!!!!!!!!!!!!!!!! #endif

.cpp file

#include "Account.h" account::account(): acct_ID{0},acct_name{0},acct_balance{ 0 }{} account::account(account& rhs): acct_ID{ rhs.acct_ID }, acct_name{ rhs.acct_name }, acct_balance{ rhs.acct_balance }{} account::account(int ID, string name, float balance) :acct_ID{ ID }, acct_name{ name }, acct_balance{ balance } { } int account::next_id = 0; account::~account() {} void account::set_ID(int ID) { acct_ID = ID; } int account::get_ID()const { int acct_ID = 0; return acct_ID; } void account::set_name(string name) { acct_name = name; } void account::input() { cout << "Enter the name: "; cin >> acct_name; float x; cout << "Enter the balance: "; cin >> x; acct_balance += x; acct_ID = next_id; next_id++; } //!!!!!!!!!!!!!!!!!!!!!!! ostream& account::display(ostream& stream) { stream << "Account name: " << this->acct_name; stream << "Account balance: " << this->acct_balance; stream << "Account ID: " << this->acct_ID; return stream; } ostream& operator<<(ostream& stream,account& Account) { stream << Account.display(stream); return stream; } //!!!!!!!!!!!!!!! void account::set_balance(float balance) { acct_balance = balance; }
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  • 1
    stream << Account.display(stream); doesn't look right, since the return value of Account.display(stream) is, itself, an ostream& and there isn't an overload for ostream << ostream. It looks like you just want Account.display(stream); return stream;. Or possibly even just return Account.display(stream); Commented May 14, 2022 at 4:54
  • 1
    Better to avoid using namespace std - see here stackoverflow.com/questions/1452721/…. Commented May 14, 2022 at 4:56

1 Answer 1

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1

The problem is that you've used:

stream << Account.display(stream);

inside the overloaded operator<<. This is a problem because account::display returns a std::ostream and there is no overload of operator<< that takes a std::ostream as a parameter.

Method 1

To solve this you can add a friend declaration for the overloaded operator<< inside the class and change the implementation of operator<< to as shown below:

class account { //other members as before //friend declaration for overloaded operator<< friend std::ostream& operator<<(std::ostream& stream, account& Account); }; //implementation of operator<< std::ostream& operator<<(std::ostream& stream,account& Account) { stream << Account.acct_ID<<" "<< Account.acct_name<<" "<<Account.acct_balance<<" "<<Account.acct_ID; return stream; }

Working demo

Method 2

Another way to solve this is to replace stream << Account.display(stream); with return Account.display(stream); as shown below:

std::ostream& operator<<(std::ostream& stream,account& Account) { return Account.display(stream); //changed this }

Demo

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2 Comments

You don't need a friend declaration since display is a public member of account. Seems simpler to just correct the usage of display in the operator<< overload. And also makes it a little easier to adapt this to a situation where, say, account is actually supposed to be a polymorphic base class and display can be made virtual but operator<< the free function cannot.
@NathanPierson Note that in my modified example, i have not used display. Also, since there is a overloaded operator<< for account, display is no longer needed for the given example.

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