Python PyQt program - Display Hello, PyQt!

Python PyQt Widgets: Exercise-1 with Solution

Write a Python program that displays the text "Hello, PyQt!" in the center of the window using PyQt.

From doc.qt.io:

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

QMainWindow Class: The QMainWindow class provides a main application window.

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

QVBoxLayout Class: The QVBoxLayout class lines up widgets vertically.

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

Qt module: PyQt5 is a set of Python bindings for the Qt application framework. It allows us to use Qt, a popular C++ framework, to create graphical user interfaces (GUIs) in Python.

Sample Solution:

Python Code:

import sys
from PyQt5.QtWidgets import QApplication, QMainWindow, QLabel, QVBoxLayout, QWidget
from PyQt5.QtCore import Qt
class HelloPyQtApp(QMainWindow):
    def __init__(self):
        super().__init__()

        # Set the window properties (title and initial size)
        self.setWindowTitle("Hello, PyQt!")
        self.setGeometry(100, 100, 400, 200)  # (x, y, width, height)

        # Create a central widget for the main window
        central_widget = QWidget()
        self.setCentralWidget(central_widget)

        # Create a QLabel widget with the text "Hello, PyQt!"
        label = QLabel("Hello, PyQt!")

        # Create a layout for the central widget and add the label
        layout = QVBoxLayout()
        layout.addWidget(label)

        # Center-align the label
        label.setAlignment(Qt.AlignmentFlag.AlignCenter)

        # Set the layout for the central widget
        central_widget.setLayout(layout)

def main():
    app = QApplication(sys.argv)
    window = HelloPyQtApp()
    window.show()
    sys.exit(app.exec_())

if __name__ == "__main__":
    main()

Explanation:

In the exercise above -

• Import the necessary modules.
• Create a "QMainWindow" named HelloPyQtApp.
• Set the window's title and initial size using self.setWindowTitle and 'self.setGeometry'.
• Create a central widget using QWidget and set it as the central widget of the main window using 'self.setCentralWidget'.
• Create a "QLabel" widget named label with the text "Hello, PyQt!".
• Create a "QVBoxLayout" for the central widget, add the label to it, and center-align the label's text.
• In the main function, we set the layout for the central widget and execute the PyQt application's event loop.

Output:

Flowchart:

Python Code Editor:

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