🏦 bank-cli — Bank Management System

A console-based Bank Management System built in C++, featuring account creation, deposits/withdrawals, loans, transaction history, and an admin panel — all backed by a singly linked list of accounts and per-account linked-list transaction logs, with data persisted to a plain text file between runs.

---

📑 Table of Contents

• Overview
• Key Features
  • User Panel
  • Admin Panel
• Tech Stack
• System Design
• Data Structures Used
• Data Persistence
• Project Structure
• Prerequisites
• Getting Started
  • 1. Clone the repository
  • 2. Build from source
• Usage Walkthrough
• Input Validation Rules
• Known Limitations
• Security Note
• Possible Future Improvements

---

📖 Overview

This project simulates a simplified banking backend from the command line. It supports two access modes:

• A User Panel, where any customer can create an account, deposit/withdraw funds, view transaction history, and take/repay loans.
• An Admin Panel, where accounts can be frozen or reactivated.

All accounts are held in memory as a linked list while the program runs, and are saved to / loaded from a local text file (AccountsInfo.txt) so data survives between sessions.

---

✨ Key Features

👤 User Panel

• Add Account — create a new account with a unique 9-digit account number, name, password, and starting balance.
• Search Account — look up an account by account number + password and view its details.
• Deposit Funds — add money to an account (blocked if the account is frozen).
• Withdraw Funds — withdraw money, with balance-sufficiency checks (blocked if frozen).
• Display All Accounts — list every account with balance, status (Active/Frozen), and loan details.
• See Transaction History — view a full chronological log of deposits/withdrawals for an account.
• Take Loan — request a loan up to a per-account loan limit (default $50,000); approved amount is credited to the balance.
• Repay Loan — repay part or all of an outstanding loan (capped automatically at the outstanding amount and available balance).

🛡 Admin Panel

• View All Accounts — the admin panel loads and displays every account on entry.
• Freeze Account — lock an account so deposits, withdrawals, and loan actions are blocked.
• Activate Account — unfreeze a previously frozen account.

---

🧰 Tech Stack

Component	Details
Language	C++ (uses <stdexcept>, exception handling, <sstream>)
Standard Library	<fstream>, <sstream>, <string>, <iomanip>, <ctime>
Platform APIs	<conio.h> (Windows-only, masked keystroke input)
Interface	Command-Line Interface (CLI)
Persistence	Flat text file (AccountsInfo.txt), custom delimiter format
Compiler	MinGW g++ / MSVC (Windows) — project includes VS Code settings

---

🏗 System Design

                    BankManagementSystem
      - head (linked list of Account*)
      - AddAccount(), DepositFunds(), WithDrawAmountFromAccount()
      - TakeLoan(), RepayLoan(), SeeTransactionHistory()
      - SaveAccountsToFile(), LoadAccountsFromFile()
      - ConfirmAccountNumber(), ConfirmPassword()
                           ▲
                           │  (public inheritance)
                        Admin
      - AdminPanel(): Freeze / Activate accounts

• Admin publicly inherits from BankManagementSystem, reusing account storage/lookup while adding the AdminPanel() freeze/activate workflow.
• main() presents a top-level menu (User Panel / Admin Panel / Exit) and dispatches to admin->Menu() or admin->AdminPanel().

---

🗃 Data Structures Used

Structure	Purpose
Singly linked list of Account	Every account created is appended as a node (Account::next); traversed linearly for lookups, display, and saving.
Singly linked list of Transaction (per account)	Each account keeps its own transaction log as a linked list (Transaction::next), appended in chronological order.

Key structs:

struct Transaction {
    string type;       // "Deposit" or "Withdraw"
    double amount;
    string timestamp;
    Transaction *next;
};

struct Account {
    string AccountNumber;
    string AccountName;
    double AccountBalance;
    bool isFrozen;
    string Password;
    Transaction *transactionHead = nullptr;
    double LoanAmount = 0.0;
    double LoanLimit = 50000.0;
    Account *next;
};

---

💾 Data Persistence

Account and transaction data is written to / read from AccountsInfo.txt in the working directory, using a custom comma/pipe/semicolon-delimited format:

AccountNumber,AccountName,Password,Balance,IsFrozen,LoanAmount,LoanLimit,[Type;Amount;Timestamp|Type;Amount;Timestamp]

• Data is saved automatically after every account-modifying action (add, deposit, withdraw, loan, repayment, freeze/activate) via SaveAccountsToFile().
• Data is loaded automatically when entering the User Menu or Admin Panel via LoadAccountsFromFile().
• Loading is idempotent — accounts already present in memory (matched by account number) are skipped rather than duplicated.

⚠️ Passwords are stored here in plain text. See Security Note below before sharing this file or this project publicly.

---

📁 Project Structure

bank-cli/
├── README.md
├── Project.cpp          # Full implementation: BankManagementSystem, Admin, main()
├── AccountsInfo.txt      # Persisted account/transaction data (plain text)
├── Project.exe            # Prebuilt Windows executable

---

✅ Prerequisites

Because the project uses <conio.h> (for _getch() and masked password input), it must be compiled and run on Windows (natively, or in a Windows VM). It will not compile as-is on Linux/macOS without modification (e.g. swapping conio.h for a portable alternative).

You'll need one of:

• MinGW-w64 g++ (recommended, e.g. via MSYS2 or the standalone MinGW installer), or
• Microsoft Visual Studio (Desktop development with C++ workload), or
• Any C++ Windows compiler with <conio.h> support.

You'll also need Git installed if you want to clone the repo (or just download the ZIP from GitHub instead).

---

🚀 Getting Started

1. Clone the repository

git clone https://github.com/<your-username>/bank-cli.git
cd bank-cli

No Git? Click Code → Download ZIP on the GitHub page instead, then extract it and open the extracted folder.

2. Build from source

1. Confirm you're in the project root (same folder as Project.cpp):

   dir Project.cpp

2. Compile with g++ (make sure MinGW's bin folder is on your PATH):

   g++ Project.cpp -o Project.exe

3. Run the compiled program:

   .\Project.exe

Using Visual Studio instead?

1. Create a new Console App (C++) project.
2. Replace the default main.cpp with Project.cpp from this repo (add it via Project → Add Existing Item).
3. Build and run with Ctrl+F5 (Start Without Debugging).

---

🖥 Usage Walkthrough

1. Launch the app — choose between User Panel, Admin Panel, or Exit.
2. User Panel menu:

   1. Add Account
   2. Search Account
   3. Deposit Funds
   4. Withdraw Funds
   5. Display All Accounts
   6. See Transaction History
   7. Take Loan
   8. Repay Loan
   9. Exit
   

3. Admin Panel — on entry, all accounts are listed automatically, then you can choose to Freeze or Activate an account by number.
4. Account numbers must be 9 digits and passwords 8+ characters; both use masked, character-by-character input via _getch().

---

🔒 Input Validation Rules

Field	Rule
Account Number	Exactly 9 digits, between 100000000 and 999999999, numeric only
Password	8 or more characters
Initial Balance	Must be greater than 0
Deposit / Withdraw Amount	Must be greater than 0; withdrawal also checked against available balance
Loan Request	Must be > 0 and not push total loan above the account's loan limit
Loan Repayment	Must be > 0, capped at both current balance and outstanding loan amount

Frozen accounts are blocked from deposits, withdrawals, taking loans, and repaying loans.

---

⚠️ Known Limitations

• Plain-text password storage — passwords are stored and compared as-is, with no hashing (see Security Note).
• No admin authentication — the Admin Panel has no login/PIN of its own; anyone launching the app can access it.
• Linear-time account lookup — accounts are stored in a linked list, so lookups are O(n) rather than using a hash map/index.
• Single-file, single-account-holder data store — no multi-branch, multi-currency, or interest-calculation support.
• Windows-only — relies on <conio.h> for keystroke capture and masked input.
• Basic error handling — malformed lines in AccountsInfo.txt are skipped with a console message rather than fully recovered.

---

🔐 Security Note

AccountsInfo.txt in this repo currently contains sample/test account data with plain-text passwords. Before pushing this project publicly:

• Delete or reset AccountsInfo.txt to remove any real or sample account numbers, names, and passwords — even test data can look like a credential leak to anyone browsing the repo.
• Consider adding AccountsInfo.txt to .gitignore going forward, so runtime-generated data never gets committed.
• Treat this project as an educational demo of data structures and file I/O, not as a template for handling real financial or personal data — plain-text password storage is not appropriate for anything beyond a classroom exercise.

---

🔮 Possible Future Improvements

• Hash passwords (e.g. with a proper cryptographic hash + salt) instead of storing them in plain text.
• Add admin authentication (username/PIN) before granting access to the Admin Panel.
• Replace the linked list with a map/unordered_map keyed by account number for O(1) lookups.
• Add interest calculation, account statements, and export to CSV.
• Cross-platform support by replacing <conio.h> with a portable input library.

---

Made with ❤️ and a linked list of good intentions.