➕➖➗ Calculator (Python)

A clean and extensible command-line calculator built using Python. Supports mathematical expressions, variables, basic functions, and easy extension—ideal for learning parsing, REPL interfaces, or quick CLI calculations.

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📋 Table of Contents

1. Overview
2. Features
3. Requirements
4. Installation
5. Usage Examples
6. Code Structure
7. Extendability
8. Contributing
9. License

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💡 Overview

This command-line calculator provides interactive evaluation of mathematical expressions, support for variables, and function definitions. It’s implemented with emphasis on modular design, clean parsing, and intuitive user experience—perfect for educational purposes or as a building block in larger tools.

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✅ Features

• ✅ Evaluate expressions: +, -, *, /, **, parentheses
• 🧮 Use variables (x = 5, y = x * 2)
• 🛠️ Define simple functions: e.g. def square(n): return n**2
• 🧵 Interactive REPL loop: Accepts assignments, expressions, and commands
• 🗑️ Session state persistence: Variables/functions retained throughout session
• 🔄 Easily extendable parser for new operators or functions

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🧾 Requirements

• Python 3.7+
• No external dependencies—implemented with ast, math, and standard libraries

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⚙️ Installation

git clone https://github.com/MisaghMomeniB/Calculator-Python.git
cd Calculator-Python

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🚀 Usage Examples

Start the REPL:

python calculator.py

Example session:

> x = 10
> y = 3 * x + 5
> y
35
> def square(n): return n * n
> square(7)
49
> (x + y) / square(2)
9.0
> quit

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📁 Code Structure

Calculator-Python/
├── calculator.py     # Main file with parser, evaluator, and REPL
└── README.md         # This file

• Uses the ast module for safe expression parsing
• Maintains a symbol table for variables/functions
• Handles errors like division by zero or syntax errors gracefully
• REPL supports built-in commands: help, quit, etc.

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⚙️ Extendability

• 🌐 Add math module functions (sin, cos, log) via symbol table
• ➕ Extend parser with new operators or syntax
• 📦 Package as a module or CLI script with argparse
• 🔐 Add sandbox restrictions for secure execution

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🤝 Contributing

Contributions are welcome! Ideas include:

• Add built-in trigonometric functions (math.sin, math.cos, etc.)
• Implement persistent session (save/load variables)
• Add unit tests (e.g., using pytest)
• Enhance REPL with history navigation (readline) or features

To contribute:

1. Fork the repository
2. Create a branch (feature/...)
3. Add tests & comments
4. Submit a detailed Pull Request

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📄 License

Released under the MIT License — see LICENSE for details.