🏧 C++ ATM & Banking System Simulation

This project is a fully functional, console-based ATM and Banking System simulation developed using C++ and Object-Oriented Programming (OOP) principles.

It features a robust architecture that handles user accounts, performs financial transactions, ensures data persistence via file I/O, and manages memory dynamically.

🚀 Technical Highlights & Features

This project demonstrates proficiency in the following Computer Science and C++ concepts:

• OOP Architecture: Utilizes Class design, Inheritance (BankAccount -> SavingsAccount), and Encapsulation.
• Polymorphism: Implements virtual functions to manage different account types dynamically using Base Class Pointers.
• Memory Management: Manual memory management using new and delete operators on the Heap. Uses std::vector<BankAccount*> to prevent Object Slicing.
• Data Persistence: Custom serialization and deserialization algorithms to save/load user data from bank_database.txt upon startup and exit.
• Transaction Logging: real-time logging of all financial activities (Deposit, Withdraw, Transfer) with timestamps to transaction_log.txt.
• Error Handling: Robust exception handling using try-catch blocks and custom throw statements to prevent runtime crashes.
• Input Validation: Helper functions to prevent infinite loops when invalid data types (e.g., characters instead of integers) are entered.
• Build Automation: Integrated Makefile for one-command compilation and execution.

📂 File Structure

• mainATM.cpp: Application entry point and main user interface loop.
• Bank.cpp: Controller class that manages account storage, authentication, and file operations.
• BankAccount.cpp: Base class defining standard account behaviors.
• SavingsAccount.cpp: Derived class with specific features like Interest Rate calculation.
• Makefile: Configuration file for automated building.
• bank_database.txt: Persistent storage for user account data.
• transaction_log.txt: Audit trail for transaction history.

🛠️ Installation & Usage

Prerequisites

• A C++ Compiler (G++ recommended)
• Make tool (Optional, but recommended)

How to Run

1. Clone the repository:

   git clone [https://github.com/YOUR_USERNAME/ATM-Project.git](https://github.com/YOUR_USERNAME/ATM-Project.git)
   cd ATM-Project

2. Compile and Run (using Makefile):

   make run

3. Clean Build Files:

   make clean

🎮 Usage Scenario

Upon launching, the system loads existing users from the database.

1. Login: Enter Account Number and PIN (System locks after 3 failed attempts).
2. Menu Options:
   • 1. Show Account Info: Displays balance and account details.
   • 2. Deposit: Adds funds to the account (Logged).
   • 3. Withdraw: deducts funds with balance checks.
   • 4. Transfer: Sends money to another valid account ID.
   • 5. Exit: Saves all data to the text database and closes the application.

👤 Author

Özge Uçar - Computer Engineering Student