7.3 Paths and Encoding

The most common file problems do not always come from read() or write(). They often come from paths and encoding. A path tells Python where to find a file; encoding tells Python how to interpret the bytes inside a text file.

Relative Paths and the Current Working Directory

A relative path is not automatically relative to the Python file. It is relative to the current working directory.

with open("data/quotes.txt", "r", encoding="UTF-8") as file:
    content = file.read()

If the current working directory is the project root, Python looks for:

project/
  data/
    quotes.txt

But if you run the program from another directory, the same "data/quotes.txt" may not be found.

UTF-8 Encoding

Text files store bytes. Encoding converts between characters and bytes. UTF-8 is one of the most common and compatible text encodings.

with open("note.txt", "w", encoding="UTF-8") as file:
    file.write("Hello, Python!")

with open("note.txt", "r", encoding="UTF-8") as file:
    print(file.read())

If writing and reading use different encodings, plain English may appear fine, but non-English text and symbols can break.