从一个函数返回所有可能的输出，然后在另一个函数中使用它

Question

The purpose of this code is to read a directory which includes 5 files, then print these files names,But when I tried to do that I got weird result.

ps [This is experience not real code and meant to return all possible outputs from a function then use it in another function to do something with it within the same class]

Here is the code:

import os


class Data:
    def __init__(self):
        self.dir = r"C:\Users\Sayed\Desktop\script\New folder"

    def files(self):
        os.chdir(self.dir)
        for files in os.listdir(self.dir):
            return files

    def df(self):
        files = self.files()
        for file in files:
            print(file)

Here is what I expected:

file (1).txt

file (2).txt

file (3).txt

file (4).txt

file (5).txt

Here is the output:

f

i

l

e

(

1

)

.

t

x

t

Answer 1

os.listdir() returns a list of the files so you don't need to iterate over it. Change your files function to this:

def files(self):
    os.chdir(self.dir)
    files = os.listdir(self.dir)
    return files

Answer 2

Your first return() leads to the loop break, hence saving only 1 filename instead of all of them. Then, since str() is an iterable type, for() loop loops through it in an absolute correct way.

I suggest you'd want to do the following:

def files(self):
    output = []
    os.chdir(self.dir)
    for files in os.listdir(self.dir):
        output.append(files)
    return output

You might want to read more on Iterables and Iterators .