📊 Factorial Calculator - GUI Version using PySide6 & QtPy

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In python

In C script

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Welcome to the Factorial Calculator! This is a simple GUI application built using PySide6 and QtPy to calculate the factorial of any non-negative integer. It's easy to use, visually appealing, and perfect for those who want to explore recursion, factorials, and GUI development.

✨ Features

• 🧮 Recursively computes factorials for any non-negative integer.
• ❌ Handles invalid inputs, such as negative numbers or non-integer values, with error messages.
• 🎨 Clean and simple graphical user interface with white text on black background for input fields.
• 🔁 Supports multiple calculations without needing to restart the app.

💡 What is a Factorial?

The factorial of a non-negative integer n is the product of all positive integers less than or equal to n. It is denoted as n!. For example:

• 5! = 5 × 4 × 3 × 2 × 1 = 120
• Special cases: 0! = 1 and 1! = 1.

🖥️ Project Overview

This project is a graphical implementation of a factorial calculator that accepts user input through a text box, computes the factorial, and displays the result in the interface. Error messages are shown when invalid inputs (negative numbers or non-integers) are entered.

🎯 How to Use

1. Requirements:

• Python 3.x installed on your system.
• The following Python packages:

  pip install PySide6 qtpy

2. Running the Program:

1. Clone or Download this repository.

2. Open a terminal or command prompt and navigate to the directory where the code is saved.

3. Run the Python script with:

   git clone https://github.com/mdriyadkhan585/Factorial-Calculator-GUI
   cd Factorial-Calculator-GUI
   python factorial_calculator_gui.py

4. The graphical user interface (GUI) will appear, where you can enter a number and calculate its factorial.

3. Example Input and Output:

Valid Input:

• Input: 5
• Output: Factorial of 5 is: 120

Invalid Input (Negative Number):

• Input: -5
• Output: Error: Factorial of a negative number doesn't exist.

Invalid Input (Non-integer):

• Input: abc
• Output: Error: Please enter a valid integer.

🛠️ Code Overview

Main Components:

• QLineEdit (Input Field): A text box where users can enter the number.
• QPushButton (Button): Triggers the calculation of the factorial.
• QLabel (Labels): Displays the result or error messages.

Key Functionality:

• Factorial Calculation: The factorial is computed using a recursive function in Python.
• Input Validation: Ensures that the user input is a valid, non-negative integer. Appropriate error messages are shown for invalid inputs.
• GUI Layout: The layout is managed using QVBoxLayout, which stacks the widgets vertically for a clean, user-friendly interface.

Code Breakdown:

• Factorial Calculation Function:

  def factorial(self, n):
      if n == 0 or n == 1:
          return 1
      else:
          return n * self.factorial(n - 1)

• Input Validation and Error Handling: The program checks if the input is a valid integer. If the input is not valid or is a negative number, it displays an appropriate error message:

  def calculate_factorial(self):
      try:
          num = int(self.input_field.text())
          if num < 0:
              self.result_label.setText('Error: Factorial of a negative number doesn\'t exist.')
          else:
              result = self.factorial(num)
              self.result_label.setText(f'Factorial of {num} is: {result}')
      except ValueError:
          self.result_label.setText('Error: Please enter a valid integer.')

• Input Box Style: The text color of the input box has been customized to make it visually appealing:

  self.input_field.setStyleSheet("color: white; background-color: black;")

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Screenshot

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📂 File Structure

Factorial-Calculator-GUI/
│
├── factorial_calculator_gui.py   # Main Python file containing the GUI code
└── README.md                     # This README file

🧑‍💻 Contributing

If you'd like to contribute or improve this project, feel free to open an issue or submit a pull request. Suggestions and feedback are always welcome!

📜 License

This project is licensed under the MIT License. See the LICENSE file for more information.

🎉 Acknowledgements

• Thanks to the PySide6 and QtPy libraries for making Python GUI development easier!
• Python community for continuous support and improvement in the language and libraries.

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🎯 Summary

This Factorial Calculator is a fun and interactive way to compute factorials using a simple yet elegant GUI. Whether you're learning Python or just need a tool to quickly calculate factorials, this project has got you covered. Enjoy coding! 😊

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