Python PyQt character counter notepad

Python PyQt Connecting Signals to Slots: Exercise-8 with Solution

Write a Python program that creates a notepad system where you can type, edit and display text. As you write, it should automatically count and show how many characters you've written. Use the PyQt module.

From doc.qt.io:

QApplication Class: The QApplication class manages the GUI application's control flow and main settings.

QWidget Class: The QWidget class is the base class of all user interface objects.

QTextEdit Class: The QTextEdit class provides a widget that is used to edit and display both plain and rich text.

QVBoxLayout Class: The QVBoxLayout class lines up widgets vertically.

QLabel Class: The QLabel widget provides a text or image display.

Sample Solution:

Python Code:

import sys
from PyQt5.QtWidgets import QApplication, QWidget, QTextEdit, QVBoxLayout, QLabel
def main():
    app = QApplication(sys.argv)
    window = QWidget()
    window.setWindowTitle("Character Counter")
    window.setGeometry(100, 100, 400, 200)  # (x, y, width, height)
    layout = QVBoxLayout()
    # Create a QTextEdit widget for text input
    text_edit = QTextEdit(window)
    layout.addWidget(text_edit)
    # Create a QLabel to display the character count
    char_count_label = QLabel("Character Count: 0", window)
    layout.addWidget(char_count_label)
    # Connect the textChanged signal of the QTextEdit to a slot that updates the character count
    def update_char_count():
        char_count = len(text_edit.toPlainText())
        char_count_label.setText(f"Character Count: {char_count}")
    text_edit.textChanged.connect(update_char_count)
    window.setLayout(layout)
    window.show()
    sys.exit(app.exec_())
if __name__ == "__main__":
    main()

Explanation:

In the exercise above -

• Import the necessary modules from PyQt5.
• Create a PyQt application and a main window.
• Design a "QTextEdit" widget called text_edit to allow text input.
• Create a "QLabel" widget called 'char_count_label' to display the character count.
• Define a slot function called "update_char_count()" that calculates the character count in "QTextEdit" and updates the label text accordingly.
• Connect the textChanged signal of "QTextEdit" to the "update_char_count()" slot function.
• Finally, we set up the layout, display the main window, and start the PyQt application's event loop.

Output:

Flowchart:

Python Code Editor:

Previous: Python PyQt custom signal example.
Next: Python PyQt simple calculator.