Question

How do I add an output operator to a class in C++?

The specific part of the task said to:

Define a ​class t​o hold accounts. Use the ​same​ stream variable! Write getters to access the fields in the accounts when printing. Add an output operator for your class. First, Repeat the print loop using this output operator.Now​ make the output operator a friend, by adding a friend​prototype​ to your account class definition. Add a line in the output operator that prints the fields “directly”, i.e. without using the getters. The vector push_back method will be passed as temporary object defined as the argument to push_back. Repeat the filling of the vector using ​emplace_back ​and again display the contents.

Under my "class AccountClass":

I was supposed to add an "output operator". Based on the instructions above, how do you do this?

Code:

#include
#include
#include
#include
#include
#include

using namespace std;

struct Account
{
   string name;
   int accno;
};

class Transaction
{
private:
   bool isDeposit;
   int amount;
   //Balance need to be static to maintain the state across the transactions
   static int balance;
public:
   void deposit(int amt)
   {
       amount = amt;
       balance += amount;
       isDeposit = true;
   }
   void withdraw(int amt)
   {
       amount = amt;
       balance -= amount;
       isDeposit = false;
   }
};

class AccountClass
{
private:
   string name;
   int accno;
   vector vHistory;
public:
   AccountClass(string nm, int acno) :name(nm), accno(acno)
   {

   }
   string getName()
   {
       return name;
   }

   int getaccno()
   {
       return accno;
   }

   void addTransaction(Transaction t)
   {
       vHistory.push_back(t);
   }
};

void readandDisplayUsingStruct(string fileName= "accounts.txt")
{
   ifstream fin;

   fin.open(fileName);

   if (!fin.is_open())
       return;

   string line;

   vector vAccounts;

   //Read each line from the file
   while (getline(fin, line))
   {
       stringstream ss(line);
       string name;
       int no;
       //Split the line into name and id using string stream
       ss >> name;
       ss >> no;
       Account acc{ name,no };
       vAccounts.push_back(acc);
   }

   cout << "The Read Values are" << endl;

   for (Account acc : vAccounts)
   {
       cout << "Name : " << acc.name << "\n";
       cout << "No : " << acc.accno << "\n";
   }

   //Clear the vector
   vAccounts.clear();

   fin.close();

   //Again do the same operation using local variables without Braces Initialisation.
   fin.open(fileName);

   if (!fin.is_open())
       return;

   string line1;

   vector vAccounts2;

   //Read each line from the file
   while (getline(fin, line1))
   {
       stringstream ss(line1);
       string name;
       int no;
       //Split the line into name and id using string stream
       ss >> name;
       ss >> no;
       Account acc;
       //Explicit initialisation
       acc.name = name;
       acc.accno = no;
       vAccounts2.push_back(acc);
   }

   std::cout << "The Read Values are" << endl;

   for (Account acc : vAccounts)
   {
       std::cout << "Name : " << acc.name << "\n";
       std::cout << "No : " << acc.accno << "\n";
   }

   fin.close();

}

void readandDisplayUsingClass(string fileName)
{
   ifstream fin;

   fin.open(fileName);

   if (!fin.is_open())
       return;

   string line;

   vector vAccounts;

   //Read each line from the file
   while (getline(fin, line))
   {
       stringstream ss(line);
       string name;
       int no;
       //Split the line into name and id using string stream
       ss >> name;
       ss >> no;
       AccountClass acc(name, no);
       vAccounts.push_back(acc);
   }

   std::cout << "The Read Values are" << endl;

   for (AccountClass acc : vAccounts)
   {
       std::cout << "Name : " << acc.getName() << "\n";
       std::cout << "No : " << acc.getaccno() << "\n";
   }

   //Clear the vector
   vAccounts.clear();

   fin.close();

}

int main()
{
   ifstream fin;

   fin.open("transactions.txt");

   if (!fin.is_open())
       return 0;

   string line;

   vector vAccounts;

   //Read each line from the file
   while (getline(fin, line))
   {
       stringstream ss(line);
       string operation;
       if (operation == "Deposit" || operation == "Withdraw")
       {
           int accno;
           ss >> accno;
           auto itr = std::find_if(vAccounts.begin(), vAccounts.end(), [&](AccountClass anAccount)
               {
                   return anAccount.getaccno() == accno;
               });

           if (itr != vAccounts.end())
           {
               Transaction t;
               int amount;
               ss >> amount;

               if (operation == "Deposit")
               {
                   t.deposit(amount);
               }
               else
               {
                   t.withdraw(amount);
               }

               itr->addTransaction(t);
           }
       }
       else if (operation == "Account")
       {
           string accName;
           ss >> accName;
           auto itr = std::find_if(vAccounts.begin(), vAccounts.end(), [&](AccountClass anAccount)
               {
                   return anAccount.getName() == accName;
               });

           if (itr == vAccounts.end())
           {
               int accno;
               ss >> accno;
               AccountClass newAccount(accName, accno);
               vAccounts.push_back(newAccount);
           }

       }

   }
}

Here is more information based on the expert’s comments: (i am just pasting the whole question since you did not specify what info you need, all my code is already posted)

Step 1: Define a ​struct​ that can hold information about bank accounts. First: ■ Each instance will hold the name for the account and an account number. We have created an input file that has at least three accounts, called "accounts.txt":

"moe 6

larry 28

curly 42"

Read a file of account information, filling a vector of account objects. Define local variables corresponding to each data item. Loop through the file, reading into these variables. Clear the vector, reopen the file (call the open method), and​repeat the above, except using curly braced intializers to intialize the instance. Close the file and display all objects.

Step 2: Define a ​class t​o hold accounts. Redo the above steps from task 1 that you did with the struct version. Use the ​same​ stream variable! Write getters to access the fields in the accounts when printing. Add an output operator for your class. First, Repeat the print loop using this output operator.Now​ make the output operator a friend, by adding a friend​prototype​ to your account class definition. Add a line in the output operator that prints the fields “directly”, i.e. without using the getters. The vector push_back method will be passed as temporary object defined as the argument to push_back. Repeat the filling of the vector using ​emplace_back ​and again display the contents.

Step 3: Add ​transactions​ to your world. A transaction will be implemented as a class and have a field to indicate whether this is a deposit or a withdrawal and a field to say how much is being deposited or withdrawn. The account class will keep track of transactions applied to it. It will need a vector to store this history of transactions. It will also need a "balance" field to indicate how much is in the account. The account will have methods "deposit" and "withdrawal" which will be passed the amount and will add an appropriate transaction object to the history and modify the balance as needed. The output operator for the account will need to change so that it can display (you format it) the history, i.e. the transactions. When you finish, test this by reading in another file "transactions.txt" that has commands such as:

"Account moe 6

Deposit 6 10

Withdraw 6 100

Account larry 28

Withdraw 6 100

Deposit 6 10

Deposit 6 10

Withdraw 6 5

Account curly 42"

Answer 1

// Output operator has been added to class AccountClass (bolded)

#include <iostream>

#include <vector>

#include <fstream>

#include <algorithm>

#include <sstream>

using namespace std;

struct Account

{

   string name;

   int accno;

};

class Transaction

{

private:

   bool isDeposit;

   int amount;

   //Balance need to be static to maintain the state across the transactions

   static int balance;

public:

   void deposit(int amt)

   {

       amount = amt;

       balance += amount;

       isDeposit = true;

   }

   void withdraw(int amt)

   {

       amount = amt;

       balance -= amount;

       isDeposit = false;

   }

};

int Transaction::balance = 0; // initialize balance to be 0 at the start

class AccountClass

{

private:

   string name;

   int accno;

   vector<Transaction> vHistory;

public:

   AccountClass(string nm, int acno) :name(nm), accno(acno)

   {

   }

   string getName()

   {

       return name;

   }

   int getaccno()

   {

       return accno;

   }

   void addTransaction(Transaction t)

   {

       vHistory.push_back(t);

   }

   // output operator declaration

   friend ostream& operator<<(ostream &out, const AccountClass &account);

};

// output operator overloading to print the name and account no of the account

ostream& operator<<(ostream &out, const AccountClass &account)

{

       out << "Name : " << account.name << "\n";

       out << "No : " << account.accno << "\n";

       return out;

}

void readandDisplayUsingStruct(string fileName= "accounts.txt")

{

   ifstream fin;

   fin.open(fileName);

   if (!fin.is_open())

       return;

   string line;

   vector<Account> vAccounts;

   //Read each line from the file

   while (getline(fin, line))

   {

       stringstream ss(line);

       string name;

       int no;

       //Split the line into name and id using string stream

       ss >> name;

       ss >> no;

       Account acc{ name,no };

       vAccounts.push_back(acc);

   }

   cout << "The Read Values are" << endl;

   for (Account acc : vAccounts)

   {

       cout << "Name : " << acc.name << "\n";

       cout << "No : " << acc.accno << "\n";

   }

   //Clear the vector

   vAccounts.clear();

   fin.close();

   //Again do the same operation using local variables without Braces Initialisation.

   fin.open(fileName);

if (!fin.is_open())

       return;

   string line1;

   vector<Account> vAccounts2;

   //Read each line from the file

   while (getline(fin, line1))

   {

       stringstream ss(line1);

       string name;

       int no;

       //Split the line into name and id using string stream

       ss >> name;

       ss >> no;

       Account acc;

       //Explicit initialisation

       acc.name = name;

       acc.accno = no;

       vAccounts2.push_back(acc);

   }

   std::cout << "The Read Values are" << endl;

   for (Account acc : vAccounts)

   {

       std::cout << "Name : " << acc.name << "\n";

       std::cout << "No : " << acc.accno << "\n";

   }

   fin.close();

}

void readandDisplayUsingClass(string fileName)

{

   ifstream fin;

   fin.open(fileName);

   if (!fin.is_open())

       return;

   string line;

   vector<AccountClass> vAccounts;

   //Read each line from the file

   while (getline(fin, line))

   {

       stringstream ss(line);

       string name;

       int no;

       //Split the line into name and id using string stream

       ss >> name;

       ss >> no;

       AccountClass acc(name, no);

       vAccounts.push_back(acc);

   }

   std::cout << "The Read Values are" << endl;

   for (AccountClass acc : vAccounts)

   {

          std::cout<<acc; // the operator<< class is used to output the name and accno

          /*std::cout << "Name : " << acc.getName() << "\n";

       std::cout << "No : " << acc.getaccno() << "\n";*/

   }

   //Clear the vector

   vAccounts.clear();

   fin.close();

}

int main()

{

   ifstream fin;

   fin.open("transactions.txt");

   if (!fin.is_open())

       return 0;

   string line;

   vector<AccountClass> vAccounts;

   //Read each line from the file

   while (getline(fin, line))

   {

       stringstream ss(line);

       string operation;

       if (operation == "Deposit" || operation == "Withdraw")

       {

           int accno;

           ss >> accno;

           auto itr = std::find_if(vAccounts.begin(), vAccounts.end(), [&](AccountClass anAccount)

               {

                   return anAccount.getaccno() == accno;

               });

           if (itr != vAccounts.end())

           {

               Transaction t;

               int amount;

               ss >> amount;

               if (operation == "Deposit")

               {

                   t.deposit(amount);

               }

               else

               {

                   t.withdraw(amount);

               }

               itr->addTransaction(t);

           }

       }

       else if (operation == "Account")

       {

           string accName;

           ss >> accName;

           auto itr = std::find_if(vAccounts.begin(), vAccounts.end(), [&](AccountClass anAccount)

               {

                   return anAccount.getName() == accName;

               });

           if (itr == vAccounts.end())

           {

               int accno;

               ss >> accno;

               AccountClass newAccount(accName, accno);

               vAccounts.push_back(newAccount);

           }

       }

   }

   return 0;

}