"# ATM"

💳 ATM Simulation System in C

A console-based ATM Simulation System built in C language that allows users to generate a PIN, check balance, deposit or withdraw money, and view their last 10 transactions.
It demonstrates file handling, linked lists, and modular programming in C.

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🧠 Features

• 🔐 PIN Generation & Validation

  • Generates a 4-digit PIN and stores it in pin.txt
  • Validates PIN before giving access to ATM functions

• 💰 Banking Operations

  • Check balance
  • Deposit and withdraw money
  • Prevents overdraft withdrawals

• 🧾 Transaction History

  • Maintains a history of the last 10 transactions
  • Uses a linked list to manage queue-based storage

• 📂 Persistent Storage

  • Saves PINs in a text file (pin.txt) for reuse across sessions

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🧩 Code Overview

Function	Description
pinGeneration()	Generates and saves a 4-digit PIN
checkPin()	Validates user-entered PIN against saved ones
showBalance()	Displays current account balance
depositMoney()	Adds user deposit to the balance
withdrawMoney()	Deducts withdrawal amount safely
saveHistory()	Saves transaction record to linked list
removeHistory()	Removes oldest transaction when limit (10) reached
showHistory()	Displays all recent transactions

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🧾 Example Console Output

ATM System

1. Generate PIN
2. Use ATM
3. Exit

Your choice: 1

PIN generated successfully Your generated PIN: 7485 Re-run the program and use ATM with this PIN

File Used

File	Purpose
ATM.c	Main program source code
pin.txt	Stores generated PINs
README.md	Project documentation

⚙️ How to Compile and Run

🖥️ On Windows (using GCC via MinGW)

gcc ATM.c -o ATM.exe
./ATM.exe