Lab: Editing and Running Python Programs

Lab: Editing and Running Python Programs#

Note

Source: Adapted from the C# edition (data/lab-edit-compile-run.rst). Python workflow replaces the C# edit-compile-run cycle; VS Code and terminal instructions are original additions.

The goal of this lab is to get a working Python program running on your computer.

The Python Workflow#

Unlike C#, Python does not require a separate compile step. The workflow is:

  1. Write a .py file with a text editor.

  2. Run it directly with python3.

There is no build or compile command.

Setting Up#

If Python 3 is not yet installed, download it from python.org. Open a terminal and verify:

$ python3 --version
Python 3.12.0

We recommend Visual Studio Code as an editor. Install the Python extension from the VS Code marketplace.

The Interactive Shell#

Before writing a file, try the interactive shell. Type python3 at the terminal prompt:

$ python3
Python 3.12.0 (default, ...)
>>>

You are now at the Python REPL (Read-Evaluate-Print Loop). Type any expression and press Enter:

>>> 2 + 3
5
>>> "Hello!"
'Hello!'
>>> print("Hello, world!")
Hello, world!

Exit with quit() or Ctrl-D.

Your First Script#

  1. Create a new file called hello.py with this content:

    print("Hello, world!")

  2. Run it from the terminal:

    $ python3 hello.py
Hello, world!

The Painting Program#

Now run the painting program from A Sample Python Program.

  1. Create a file called painting.py and type in the program.

  2. Run it and verify you get the same output as shown in the sample run.

  3. Run it a second time with different values (for example, length 15 and width 6.5) and check that the output is correct.

Calculation of Room Paint Requirements
Enter room length: 15
Enter room width: 6.5
The wall area is 344.0 square feet.
The ceiling area is 97.5 square feet.