atm.cpp

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

string accountNumber = "12345";
string pin = "0000";
double balance = 10000;

// Function declarations
void loadData();
void saveData();
bool login();
void menu();
void checkBalance();
void withdrawMoney();
void depositMoney();
void changePIN();

int main() {
    loadData();

    cout << "=====================================\n";
    cout << "      WELCOME TO ATM SYSTEM\n";
    cout << "=====================================\n";

    if (login()) {
        menu();
    } else {
        cout << "\nToo many wrong attempts. Card blocked!\n";
    }

    return 0;
}

// Load data from file
void loadData() {
    ifstream file("account.txt");
    if (file) {
        file >> accountNumber >> pin >> balance;
        file.close();
    }
}

// Save data to file
void saveData() {
    ofstream file("account.txt");
    file << accountNumber << " " << pin << " " << balance;
    file.close();
}

// User login
bool login() {
    string acc, enteredPin;
    int attempts = 3;

    while (attempts > 0) {
        cout << "\nEnter Account Number: ";
        cin >> acc;
        cout << "Enter PIN: ";
        cin >> enteredPin;

        if (acc == accountNumber && enteredPin == pin) {
            cout << "\nLogin Successful!\n";
            return true;
        } else {
            attempts--;
            cout << "Wrong credentials. Attempts left: " << attempts << endl;
        }
    }
    return false;
}

// Main menu
void menu() {
    int choice;
    do {
        cout << "\n========== MAIN MENU ==========\n";
        cout << "1. Check Balance\n";
        cout << "2. Withdraw Money\n";
        cout << "3. Deposit Money\n";
        cout << "4. Change PIN\n";
        cout << "5. Exit\n";
        cout << "Enter your choice: ";
        cin >> choice;

        switch (choice) {
            case 1:
                checkBalance();
                break;
            case 2:
                withdrawMoney();
                break;
            case 3:
                depositMoney();
                break;
            case 4:
                changePIN();
                break;
            case 5:
                saveData();
                cout << "\nThank you for using ATM!\n";
                break;
            default:
                cout << "Invalid choice!\n";
        }
    } while (choice != 5);
}

// Check balance
void checkBalance() {
    cout << "\nYour current balance is: Rs. " << balance << endl;
}

// Withdraw money
void withdrawMoney() {
    double amount;
    cout << "\nEnter amount to withdraw: ";
    cin >> amount;

    if (amount <= 0) {
        cout << "Invalid amount!\n";
    } else if (amount > balance) {
        cout << "Insufficient balance!\n";
    } else {
        balance -= amount;
        cout << "Please collect your cash.\n";
        cout << "Remaining balance: Rs. " << balance << endl;
        saveData();
    }
}

// Deposit money
void depositMoney() {
    double amount;
    cout << "\nEnter amount to deposit: ";
    cin >> amount;

    if (amount <= 0) {
        cout << "Invalid amount!\n";
    } else {
        balance += amount;
        cout << "Amount deposited successfully.\n";
        cout << "Updated balance: Rs. " << balance << endl;
        saveData();
    }
}

// Change PIN
void changePIN() {
    string oldPin, newPin;
    cout << "\nEnter old PIN: ";
    cin >> oldPin;

    if (oldPin == pin) {
        cout << "Enter new PIN: ";
        cin >> newPin;
        pin = newPin;
        cout << "PIN changed successfully.\n";
        saveData();
    } else {
        cout << "Wrong old PIN!\n";
    }
}