Choosing and Setting Up a Python Editor

From Editor to Saved Program

Writing code in an editor is only the beginning. If you want to keep the program, reopen it, edit it, run it later, or share it with someone else, you must save it as a file on your computer. The essential choices are the editor, the filename, and the folder where the file will live.

The .py Filename Extension

A Python source filename has two essential parts: a name you choose and the .py extension that you must include. In hello.py, hello is the chosen name and .py is the required extension. The extension tells the operating system and text editors that the file contains Python code, and it allows the Python interpreter to recognize the file as a Python program.

Saving Code into a File

The saving workflow is straightforward. Open a plain-text editor, write your Python code, choose a meaningful filename, select a location, and save the file with the .py extension. When you click Save, the code in the editor is written to computer storage as the file you specified.

File Contents and Editor Display

Before saving, the code exists in the editor while you are working on it. Saving writes that code to computer storage as a file. The file is independent of the editor: after saving, you can close the editor or turn off the computer, and the file remains in the selected folder exactly as it was saved.

Organizing Python Programs

A Python file can be saved in any folder as long as you know where that folder is. However, a dedicated folder makes your work easier to organize as you create more programs. Create one folder specifically for Python programs, such as Python_Programs or My_Python_Code, on your Desktop or in your Documents folder. Save your Python files there so they remain together and are easier to find and run later.

• Create one folder dedicated to your Python programs.
• Choose a location you can find again, such as the Desktop or Documents folder.
• Use meaningful filenames for individual programs.
• Use underscores instead of spaces in filenames.
• Avoid special characters in filenames.
• After saving, verify that the file is in the intended folder and that the name ends in .py.

Filename and Saving Mistakes

• Leaving out the .py extension

  The operating system and Python interpreter rely on the extension to recognize the file as a Python source file.

  Fix: Include .py at the end of the filename.

• Using a word processor instead of a plain-text editor

  The added formatting cannot be interpreted as Python code.

  Fix: Use a plain-text editor for writing and saving Python programs.

• Using spaces or special characters in the filename

  The recommended filename format uses underscores instead of spaces and avoids special characters.

  Fix: Choose a meaningful name that uses underscores where needed and ends in .py.

• Saving programs in unrelated locations

  The files become harder to find and manage as the number of programs grows.

  Fix: Create one dedicated folder and save your Python programs there.

• Assuming code remains after closing an interactive shell or notebook

  Code entered interactively runs immediately but disappears when the program is closed.

  Fix: Save code as a .py file when you need to keep, reuse, or share it.

File Setup Practice

Essential Saving Rules

1. Use a plain-text editor rather than a word processor.
2. Save every Python program with the .py extension.
3. Choose a meaningful filename, use underscores instead of spaces, and avoid special characters.
4. Keep your programs in one dedicated folder so they are easy to find.
5. Remember that saving writes the code from the editor to a lasting file on computer storage.
6. Verify both the filename and the folder after saving.