Scientific Calculator in C

A scientific calculator implemented in C with GTK4 GUI. Originally intended as a clone of Google's calculator but evolved into a more comprehensive scientific calculator application.

Features

• Scientific Functions:

  • Basic arithmetic operations (+, −, ×, ÷)
  • Trigonometric functions (sin, cos, tan) with DEG/RAD mode toggle
  • Inverse trigonometric functions (sin⁻¹, cos⁻¹, tan⁻¹)
  • Logarithmic functions (ln, log)
  • Exponential functions (e^x)
  • Square root (√), power (x^y), and factorial (!)
  • Constants (π, e)
  • Parentheses for complex expressions
  • Reciprocal (1/x) and negation (+/−)

• Calculator Functions:

  • Decimal point support
  • Percentage calculations
  • Clear (C) and backspace (←) functionality
  • Proper operator precedence and chaining

• GUI Features:

  • GTK4-based interface with responsive grid layout
  • Clean, functional design with color-coded buttons
  • Large monospace display for clear number visibility
  • Support for both keyboard input and button clicks

Build Requirements

• GTK 4.0 or later
• GLib 2.0
• Cairo graphics library
• Pango text rendering
• Graphene geometry library
• GCC compiler
• Math library (libm)

Building

cd src
make

Running

./calculator

Or use the convenience target:

make run

Testing

The project includes unit tests:

make test

Project Structure

• calculator.c - Main GUI application and event handlers
• calculator_logic.c - Core calculator computation logic
• calculator_logic.h - Calculator logic header and data structures
• Makefile - Build configuration with GTK4 and math library support
• test_calculator.c - Unit tests for calculator logic

Usage

1. Click number buttons to enter values
2. Click operator buttons (+, −, ×, ÷) to perform operations
3. Use scientific function buttons (sin, cos, tan, etc.) for advanced calculations
4. Press = to calculate the result
5. Use ← to delete the last digit
6. Use C to clear everything
7. Toggle between DEG and RAD modes using the DEG/RAD button
8. Use parentheses to group operations

Technical Details

The calculator uses a stack-based expression evaluator that handles operator precedence correctly. The GUI is separated from the calculation logic, following a clean architectural pattern.

License

This project is licensed under the MIT License.

Contributing

Feel free to submit issues or pull requests to improve the calculator functionality or user interface.