📝 CLI Todo App + Calculator Module

A Rust-powered command-line application that combines a Todo List Manager, a Basic Calculator, and a Multithreaded Calculator — all in one tool.

This project is designed to help beginners and intermediates strengthen their understanding of Rust fundamentals, including ownership, borrowing, modules, collections, user input, and multithreading.

---

🚀 Features

✅ Todo App

• Add tasks
• List tasks
• Remove tasks
• Mark tasks as completed
• Clean, simple CLI interface

🧮 Calculator Module

• Addition
• Subtraction
• Multiplication
• Division (with safe error handling)
• Separated into its own Rust module for reusability

⚡ Multithreaded Calculator

• Executes operations on multiple threads
• Demonstrates concurrency using std::thread
• Ideal for CPU-heavy or background computations

---

🧩 Project Structure

Each module handles a dedicated portion of the program, designed using clean Rust architecture.

---

📦 Installation

First, ensure Rust is installed:

rustc --version cargo --version

▶️ Running the App

Inside the project directory, run:

cargo run

Welcome to the CLI Todo App with Calculator Module!

Select an option:

1. Todo App
2. Calculator
3. Multithreaded Calculator
4. Exit

📘 Usage Guide

📝 Todo App Menu

Selecting Todo App gives you:

1. Add Task
2. List Tasks
3. Remove Task
4. Mark Task as Completed
5. Back to Main Menu

Examples

Add → "Finish Rust project"

List → Shows pending & completed tasks

Remove → Remove by index

Mark complete → Updates task status

🧮 Calculator Usage

Input order:

Enter first number Enter second number Choose operation: +, -, *, /

Example 5 3 * Result: 15

⚡ Multithreaded Calculator Usage

You will see:

Enter number A: Enter number B: Choose operation to run in a separate thread:

The calculation runs on a separate thread, demonstrating Rust concurrency.

🧠 Concepts Demonstrated

This project reinforces many core Rust concepts:

Rust module organization

Structs & enums

Ownership and borrowing

Collections (Vec)

Pattern matching

Error handling

Iterators

User input parsing

Concurrency with threads

A strong foundation for advanced Rust and future Solana development.

🛠️ Optional Future Enhancements

Ideas to extend the app:

File-based task persistence

Task timestamps

Task categories or priority levels

Colored output

Batch operations using threads

Terminal UI using crossterm or ratatui

📄 License

This project is open-source. Feel free to modify, extend, or use it for learning.