Your First QtWidgets Application

As with any other programming framework, you start with the traditional “Hello World” program.

Here is a simple example of a Hello World application in PySide6:

import sys
from PySide6.QtWidgets import QApplication, QLabel

app = QApplication(sys.argv)
label = QLabel("Hello World!")
label.show()
app.exec()

When you execute it the code, the application will look like:

For a widget application using PySide6, you must always start by importing the appropriate class from the PySide6.QtWidgets module.

After the imports, you create a QApplication instance. As Qt can receive arguments from command line, you may pass any argument to the QApplication object. Usually, you don’t need to pass any arguments so you can leave it as is, or use the following approach:

app = QApplication([])

After the creation of the application object, we have created a QLabel object. A QLabel is a widget that can present text (simple or rich, like html), and images:

# This HTML approach will be valid too!
label = QLabel("<font color=red size=40>Hello World!</font>")

Note

After creating the label, we call show() on it.

Finally, we call app.exec() to enter the Qt main loop and start to execute the Qt code. In reality, it is only here where the label is shown, but this can be ignored for now.