Unexpected output while iterating over list

Question

I am printing the files name from current directory in my os . files in my current directory are :test.py,Bob.txt,Alice.txt,

import os
files=os.listdir('.')
print(files)
#['test.py','Bob.txt','Alice.txt']
for file in files:
    if file.endswith(".txt"):
        print(file)
    else:
        print(".txt no such file in this directory") 
        break

I am getting output ".txt no such file in this directory"

but it should be print files name Bob.txt and Alice.txt please explain why and how?

Answer 1

With how you currently have your code structured, it will go to the else statement as soon as it encounters a single file that doesn't end with .txt . Since it seems like you want files that do end with .txt , it is possible to use list comprehension to quickly filter through the list.

txtfiles = [file for file in files if file.endswith(".txt")]

if len(txtfiles) > 0:
    for file in txtfiles:
        print(file)
else:
    print(".txt no such file in this directory")

An alternative is to do the filtering manually within a for loop, only checking for an empty list at the end.

Answer 2

The if/else is run for each file in the list. As soon as you hit a non txt file, the else clause runs, prints the unwanted message and breaks out of the loop. Instead, you could track whether you've seen a txt file and print afterwards

import os
files=os.listdir('.')
print(files)
has_txt = False
for file in files:
    if file.endswith(".txt"):
        has_txt = True
        print(file)
if not has_txt:
    print(".txt no such file in this directory") 

But I think a list comprension to filter the directory list is the way to go.

import os
txt_files = [name for name in os.listdir('.') if name.endswith(".txt")]
if txt_files:
    print("\n".join(txt_files))
else:
    print(".txt no such file in this directory") 

Answer 3

If you wanted to check for .txt file recursively in the all the subdirectories then you can use os.walk

import os
path_of_directory = "."
flag = False
for directory, dir_names, files_in_dir in os.walk(path_of_directory):
    for each_file in files_in_dir:
        if os.path.splitext(each_file)[-1] == ".txt":
            print(each_file)
            flag = True

if not flag:
    print("No .txt file")

Answer 4

Take a look for loop examples .

The problem is break ends the loop

for file in files:
    if file.endswith(".txt"):
        print(file)
    else:
        print(".txt no such file in this directory") 
        break

While it iterates the loop the first item is test.py

It does not match .endswith(".txt") , remove the break should work.