Simple Banking System (C)

A modular ATM-based banking system implemented in C using multiple source files and a header file.
This project demonstrates structured programming, function modularization, pointer usage, and separate compilation in C.

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📌 Project Description

This project simulates a basic ATM system with PIN authentication and core banking operations.
The application is divided into multiple source files to maintain modular design and clean code structure.

The system requires a valid PIN to access banking operations and allows the user to perform basic account transactions through a console interface.

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🚀 Features

🔐 PIN-Based Login

• User must enter a PIN to access the ATM.
• Maximum of 3 attempts allowed.
• If incorrect PIN is entered 3 times, the program exits.

💰 Deposit

• Allows the user to deposit money.
• Only positive amounts are accepted.
• Invalid deposits are rejected.

💵 Withdraw

• Allows the user to withdraw money.
• Withdrawal amount must:
  • Be greater than 0
  • Not exceed current balance.
• Prevents overdrawing the account.

📊 Check Balance

• Displays the current account balance.

❌ Exit

• Allows the user to exit the ATM system safely.

🧩 Modular Structure

• ATM.c → Handles login system and main ATM menu.
• Account.c → Handles deposit, withdrawal, and balance operations.
• Account.h → Contains function declarations.
• Demonstrates header file usage and separate compilation.

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🗂 Project Structure

Simple-Banking-System/
│
├── ATM.c
├── Account.c
├── Account.h
└── README.md

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📥 Installation

Clone this repository:

git clone https://github.com/codexbutcher/Simple-Banking-System.git

Navigate into the project directory:

cd Simple-Banking-System

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🛠 How to Compile

Using GCC:

gcc ATM.c Account.c -o atm

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▶ How to Run

On Windows:

atm.exe

On Linux / Mac:

./atm

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🧑‍💻 How to Use the Program

1. Run the program.
2. Enter the PIN: 1234
3. After successful login, choose from the menu:
   • 1 → Deposit
   • 2 → Withdraw
   • 3 → Check Balance
   • 4 → Exit
4. Follow the on-screen instructions.
5. If the wrong PIN is entered 3 times, the program terminates.

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🧠 Concepts Used

• Functions
• Pointers (pass by reference)
• Header files
• Separate compilation
• Switch-case statements
• Loops (do-while, while)
• Conditional logic

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🎯 Purpose of This Project

This project was built to strengthen understanding of:

• Modular programming in C
• Code organization across multiple files
• Function declarations and definitions
• Basic ATM system logic implementation