Why is choose option looping?

Question

Trying to create an algorithm that an ATM would use, but after selecting a choice to enter card number or exit, the code keeps looping back to this question. Still new to C++ and this has me stumped. I believe that my issue is at the beginning of the code because I can't get far into the program before it starts to loop.

#include <iostream>
#include <string>
#include <vector>
using namespace std;
// abstract class
struct Person
{
    string name;
    virtual void printName() = 0;
};
//Account class
struct Account : public Person
{
    long cardNumber;
    int pin; // 4 digit pin
    double balance;

    Account()
    {
        cardNumber = 0;
        pin = 1234;
        balance = 0;
    }

    Account(long c, int p, double bal)
    {
        cardNumber = c;
        pin = p;
        balance = bal;
    }

    void withdraw()
    {
        double amount;
        cout << "Enter amount less than " << balance << ": ";
        cin >> amount;
        balance -= amount;
        checkBalance();
    }

    void checkBalance()
    {
        cout << "Your balance is: " << balance << endl;
    }

    void changePin()
    {
        int Pin;
        cout << "ENTER NEW PIN: ";
        cin >> Pin;
        pin = Pin;
        cout << "PIN CHANGED \n";
    }

    void printName()
    {
        cout << "Name of Person: ";
        cout << name << endl;
    }
};

struct ATM
{
    vector<Account> accounts;

    void Login()
    {
        long cardNumber;
        cout << "Enter cardNumer: ";
        cin >> cardNumber;
        for (int i = 0; i < accounts.size(); ++i)
        {
            if (cardNumber == accounts[i].cardNumber)
            {
                long pin;
                cout << "Enter PIN: ";
                cin >> pin;
                if (pin == accounts[i].pin)
                {
                    int choice = 0;
                    cout << "1. WITHDRAW\n";
                    cout << "2. CHECK BALANCE\n";
                    cout << "3. CHANGE PIN\n";
                    cout << "4. EXIT\n";
                    cout << "Enter your choice: ";
                    cin >> choice;
                    switch (choice)
                    {
                    case 1: accounts[i].withdraw();
                        break;
                    case 2: accounts[i].checkBalance();
                        break;
                    case 3: accounts[i].changePin();
                        break;
                    case 4: cout << "THANK YOU FOR USING\n";
                        break;
                    default: cout << "NO A VALID CHOICE BYE!!\n";
                    }
                }
                else
                    cout << "WRONG PIN BYE!!";
            }
        }
    }
};

int main()
{
    int choice = 0;
    ATM A;
    Account temp;
    temp.name = "John Doe";
    temp.cardNumber = 123456789;
    temp.pin = 1234;
    temp.balance = 30000;
    A.accounts.push_back(temp);
    temp.name = "David Joe";
    temp.cardNumber = 987654321;
    temp.pin = 4321;
    temp.balance = 10000;
    A.accounts.push_back(temp);
    while (choice != 2)
    {
        cout << "1. LOGIN\n";
        cout << "2. EXIT\n";
        cout << "ENTER CHOICE: ";
        cin >> choice;
        switch (choice)
        {
        case 1: A.Login();
            break;
        case 2: cout << "BYE!!\n";
            break;
        default: cout << "ENTER A VALID CHOICE\n";
        }
    }
}

Any help is much appreciated.

Answer 1

Other than a misspelt cardNumer, and a signed/unsigned comparison warning which can be fixed with:

for (size_t i = 0; i < accounts.size(); ++i)

there's nothing really wrong with that code, as evidenced by the following run:

1. LOGIN
2. EXIT
ENTER CHOICE: 1
Enter cardNumer: 7
1. LOGIN
2. EXIT
ENTER CHOICE: 1
Enter cardNumer: 123456789
Enter PIN: 1234
1. WITHDRAW
2. CHECK BALANCE
3. CHANGE PIN
4. EXIT
Enter your choice: 2
Your balance is: 30000
1. LOGIN
2. EXIT
ENTER CHOICE:

If you enter an invalid card number, it will go back to the main menu but the question is not really clear on that behaviour, and you haven't specified what test data you're using.