Installing Python and PyCharm

Installing Python

Windows: the install manager

The main platform for the labs is Windows 11. Open https://www.python.org/downloads/windows/ and install Python Install Manager. Do not confuse the manager with the runtime itself: it downloads and maintains the Python versions you need. The manager's commands are documented at https://docs.python.org/3.14/using/windows.html.

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python.org/downloads/windows: Install Manager and Python 3.14

Figure 1.3. Downloading Python for Windows

After installation, open a new PowerShell window and run:

py install 3.14
py list
py -V:3.14 --version
python --version
where.exe python

py list shows installed versions, while where.exe shows the executables it finds. In PowerShell, use where.exe specifically, because the short form where has a different meaning. If py install is not recognized, the old Python Launcher may be running: use pymanager install 3.14 and check the command's source. Do not remove existing interpreters until you know which projects need them.

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PowerShell: py install 3.14; py list; python –version

Figure 1.4. Checking the installed Python 3.14

The traditional .exe installer is still available for Python 3.14, but is marked deprecated; releases for 3.16 and later are not planned. The Add python.exe to PATH checkbox belongs specifically to that installer. If the command opens Microsoft Store, check App execution aliases and the path to the Python you need; do not change all system aliases at random.

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python: 2 ** 100; import sys; sys.version; exit()

Figure 1.5. An interactive Python session

Linux and macOS

On Linux, the system python3 may have a different version from the one required for the course. Do not use it to replace system components. On Debian/Ubuntu, the environment creation module may require a separate package:

python3 --version
sudo apt update
sudo apt install python3-venv
python3 -m venv .venv
source .venv/bin/activate

These commands use the distribution's version. If you specifically need 3.14, install uv using its official instructions, then run uv python install 3.14, followed by uv venv --python 3.14 .venv in a new project directory. Do not run both environment creation commands on the same existing environment unnecessarily.

On macOS, you can install the .pkg from https://www.python.org/downloads/macos/. Check python3.14 --version; create an environment with python3.14 -m venv .venv. After activation with source .venv/bin/activate, the python command should point to the project environment. On both systems, install project packages without sudo pip.

JetBrains PyCharm

An IDE (Integrated Development Environment) combines an editor, execution, a debugger, and project management tools. PyCharm does not replace Python: the IDE runs the selected interpreter. Download: https://www.jetbrains.com/pycharm/download/.

PyCharm now ships as a unified product. Core features remain free; you can continue using them after the Pro trial. Paid features are not needed for this lab. Check educational terms separately: https://www.jetbrains.com/academy/student-pack/. Do not treat a student license as permission for unrestricted commercial use.

For PyCharm 2026.2, the documentation specifies 8 GB of total RAM, 3 GB available for the IDE, 10 GB of disk space, and a display of at least 1280×720. There is no need to install Java separately: JetBrains Runtime is bundled. Current requirements: https://www.jetbrains.com/help/pycharm/installation-guide.html.

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PyCharm download: Windows, version and download button

Figure 1.6. The PyCharm download page

Install the IDE directly or through JetBrains Toolbox App. On first launch, choose the English interface so that command names match this material. Importing old settings is optional. From the welcome window, you can create a project, open a directory, or clone a repository (Fig. 1.7).

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Welcome: New Project, Open, Clone Repository

Figure 1.7. The PyCharm welcome window

Your first project

1. Click New Project and choose Pure Python.
2. Specify the directory C:\Labs\hello; the project name matches the directory name.
3. Choose Project venv and base Python 3.14. The environment will be in .venv.
4. Create main.py using New → Python File. If the IDE has already created an example, replace it with the code below.
5. For the first run, right-click the file and choose Run 'main'. Once the configuration exists, you can run it again with Shift+F10.

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New Project: Pure Python; hello; Project venv; Python 3.14

Figure 1.8. A project with its own environment

"""The first program in the course."""


def main():
    print("Hello, Python!")


if __name__ == "__main__":
    main()

Program output:

Hello, Python!

In the Run window, the IDE also displays the launch command and exit code. Process finished with exit code 0 means the process ended successfully, but does not prove that the calculations are correct. Check the result itself as well. Project creation instructions: https://www.jetbrains.com/help/pycharm/creating-empty-project.html.

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main.py; Project; Run with Hello, Python!; interpreter widget

Figure 1.9. The editor and execution result

The Project window shows files, Run shows the output of a separate process, Python Console provides interactive Python, and Terminal provides a command shell. Enter python main.py in the terminal, not after >>>. Use Ctrl+Alt+L to format code, Alt+Enter for a suggested fix, and Ctrl+Q for documentation in the default Windows keymap. Check reassigned shortcuts under Settings → Keymap.

Module structure and errors

A module is a file containing Python code. A documentation string (docstring) is appropriate at the beginning, followed by imports, function definitions, and the entry point. def main(): defines a function but does not execute it. Calling main() runs its body. The __name__ == "__main__" check distinguishes direct execution from import: importing loads the definitions without making this call.

Indentation defines blocks. Use four spaces per level, rather than mixing spaces and tabs. A comment begins with # and explains the intent. Write variable and function names in snake_case, and constants in UPPER_CASE. Style rules: https://peps.python.org/pep-0008/.

Deliberately replace print with prnt and run the file. In the traceback, find the last line with the error type, then the file and line number above it. NameError means an unknown name; an editor suggestion is not an automatic correction. Fix the error and run the program again to check the result.

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prnt("Hi"); Run: NameError and clickable source line

Figure 1.10. Reading an error message

Table 1.2. Initial errors and where to look for their causes

Error	Example cause	What to check
SyntaxError	Missing : after def	The syntax of the indicated line
IndentationError	No indentation in the function body	Four spaces per level
NameError	prnt instead of print	The name's spelling and definition
ModuleNotFoundError	The package is in another environment	The interpreter path

Example: command-line arguments

The args.py file shows how the shell passes data to a program. This differs from input: values are provided before the process starts.

"""Displays arguments without converting them."""
import sys

print("File:", sys.argv[0])
print("Arguments:", sys.argv[1:])

Running python args.py alpha "beta gamma" produces:

File: args.py
Arguments: ['alpha', 'beta gamma']

Quotes combine two words into one argument and usually are not part of its value. In PyCharm, open Run → Edit Configurations and enter these values in the script parameters field. Also check Working directory: relative paths depend on it. Do not append arguments to the filename itself.