File Paths (os & pathlib)

Paths: relative vs absolute

A relative path starts from the current folder. An absolute path starts from the drive root.

Joining paths safely

Use os.path.join() so your code works on Windows, macOS, and Linux.

python
import os
path = os.path.join("data", "notes.txt")
print(path)

Using pathlib (recommended)

pathlib gives you a clean, object-style way to work with paths.

python
from pathlib import Path
path = Path("data") / "notes.txt"
print(path)

Checking if a path exists

python
from pathlib import Path
path = Path("data") / "notes.txt"
print(path.exists())

Listing files in a folder

python
from pathlib import Path
for p in Path("data").iterdir():
    print(p.name)

Creating folders

python
from pathlib import Path
Path("output").mkdir(exist_ok=True)

Common mistakes to avoid

• Building paths with string +.
• Using backslashes directly (\\) instead of Path() or os.path.
• Assuming a file exists without checking.

What you should understand after this lesson

• The difference between relative and absolute paths.
• How to build paths safely with os.path or pathlib.
• How to check for files and folders.