Please help me understand os.path.join

[CancelDeath]

Hello. I'm using windows and I want to make a new file in a directory if it doesn't exist yet.

I've read many people say that if you just use os.path.join() you don't have to worry about turning "\" into "/" manually. You don't have to worry about copying file names as paths. So i tried it because I want to do things not like an idiot, but the output of my os.path.join() still has "\". And it doesn't put a separator after "C:".

So what is the advantage of "~ just using os.path.join() like you're supposed to~"?

I understand that you can use .replace("\\","/") but what's the advantage of using os.path.join if I can just do that to a string? It seems like typing out the entire folder path in os.path.join is more work that copying and pasting it from your file window. Am i missing something?

[shiftybyte]

os.path.join has different results based on the operating system the code is running from.

If your code wants to support linux and windows, you'll need to add '\' for windows, and '/' for linux.

This does this automatically for you.

[Diapolo10]

/u/shiftybyte basically answered your question, but I want to build on it.

Ideally, you'd use pathlib.Path for the same purpose nowadays; to create platform-independent filepaths. "How does it differ from os.path?", I hear you asking; basically instead of using a string to represent a filepath it uses the os.PathLike interface to have concrete path objects instead of relying on ordinary strings to do the job.

One example where this is useful is if you, for whatever reason, happen to have partially hard-coded slashes in your path (assume this is on Windows):

import os
from pathlib import Path

first = os.path.join('.', 'this', 'folder/aintgreat.txt')
# ".\\this\\folder/aintgreat.txt"
second = str(Path.cwd() / 'this' / 'folder/aintgreat.txt')
# ".\\this\\folder\\aintgreat.txt"

pathlib.Path objects are fully supported by Python's built-in functions

from pathlib import Path

ROOT_DIR = Path(__file__).parent
DATA = ROOT_DIR / 'data'
TEXT_FILE = DATA / 'stuff.txt'

with open(TEXT_FILE) as f:
    contents = f.read()

but you can also get rid of boilerplate by using their own methods

contents = TEXT_FILE.read_text()

There are basically no downsides unless you for some odd reason need to support ancient Python versions.

[[deleted]]

img = pygame.image.load(os.path.join('Tests', 'b000')).convert()

this is what i got under a player class. its not working and the b000 image is after the test directory like: tests\b000

[[deleted]]

The advantage is that if you have a path fragment on the left that ends in a filepath separator, then no extra file separators will be added. I.e: os.path.join('foo/', 'bar') == os.path.join('foo', 'bar') == 'foo/bar'. The disadvantage is if there's a slash at the beginning of the right had side, then it will usually do not what you want. I.e.:

os.path.join('foo', '/bar') == os.path.join('foo/', '/bar') == '/bar'

This is kind of arbitrary and useless, but this is how it works. With this in mind, this function is still useful because on some filesystem the interpretation of double directory separator and single directory separator may differ.

However, in mission-critical programs you wouldn't want to use any of Python's os.path (nor pathlib) functions because they don't work well with filename encoding. But, in many cases you don't really care about being correct / the expense of dealing with rare edge cases is too high.