FEN Validator - Chess Notation Validator

The FEN Validator is a Python application built with PyQt5 that validates and visualizes FEN (Forsyth-Edwards Notation) strings for chessboard configurations. In addition to validating FEN syntax, the application graphically displays the arrangement of pieces on the board.

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📋 Features

• FEN Validation: Checks if a FEN string is valid according to chess rules.
• Board Visualization: Displays the chessboard with pieces based on the FEN string.
• Predefined Examples: Includes examples of valid and invalid FEN strings for testing.
• Graphical Interface: Built with PyQt5, offering an intuitive user experience.

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🛠️ Requirements

To run this project, you need:

• Python 3.8 or higher.
• PyQt5: For the graphical interface.
• Additional Libraries: re (regular expressions) and random.

Installing Dependencies

pip install PyQt5

🚀 How to Use

Clone the repository:

git clone https://github.com/santig005/FEN-Validator.git
cd FEN-Validator

Run the application:

python app.py

User Interface:

Enter a FEN string in the input field.

The application will automatically validate the FEN string and display the corresponding board.

If the notation is invalid, a detailed error message will be shown.

FEN Examples

The application includes buttons to load predefined examples:

Starting Position:

rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1

Scholar's Mate:

r1bqk1nr/pppp1Qpp/2n5/2b1p3/2B1P3/8/PPPP1PPP/RNB1K1NR b KQkq - 0 4

Alternating Queens:

QqQqQqQq/qQqQqQqQ/QqQqQqQq/qQqQqQqQ/QqQqQqQq/qQqQqQqQ/QqQqQqQq/qQqQqQqQ b - - 0 4

Invalid FEN:

8/6.app/p1n2k2/1fp6/3N#P/1q6/5K2/8 s qk e6 51 1

🧠 How It Works

FEN Validation

The application uses regular expressions to validate FEN syntax. It checks:

FEN Structure: 8 rows separated by /.

Pieces and Numbers: Each row must sum to 8 squares (pieces or numbers indicating empty squares).

Additional Details: Turn, castling rights, en passant, etc