Python change strings line by line in all files within a directory

Question

So I have some files located in directory. Some of the files contain paths like this and some are empty: C:\d\folder\project\folder\Folder1\Folder2\Folder3\Module.c

What would be the best way to cut it just by counting backslashes from the end: So in this case we need to cut everything what is after 4th backslash when counting backward:

Folder1\Folder2\Folder3\Module.c

I need some function that will go through all files and do this on each line of a file.

Current code which do not work for some reason is:

directory = os.listdir(//path_to_dir//)
for file in directory:
    with open (file) as f:
        for s in f:
            print('\\'.join(s.split('\\')[-4:])) 

Answer 1

I would try something like this:

from pathlib import Path

def change(s):
    return '\\'.join(s.split('\\')[-4:])

folder = Path.cwd() / "folder" # here is your folder with files
files = folder.glob("*")

for f in files:
    with open(f, "r") as file:
        content = file.read()

    lines = content.split('\n')
    new_lines = []

    for line in lines:
        new_lines.append(change(line))

    with open(f, "w") as file:
        file.write("\n".join(new_lines))

It look for all files in the subfolder folder, does replacing on every line of every file and saves the files.