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FileNotFoundError · Exercises
Core Python

FileNotFoundError Exercises

4 exercises that build on the Python FileNotFoundError: No such file or directory lesson, from easy to hard. Each one is checked in your browser when you press Check. Stuck? Use the hint before peeking at the solution.

What this lesson covers: A FileNotFoundError means Python tried to open or access a file or folder path that does not exist, usually because the path is wrong relative to where the program is running. By the end you can read a FileNotFoundError, find the real reason the path failed, and fix it by correcting the path, creating missing folders or handling the error. You will practise: Predict which files are found; Fix the missing export folder; Write read_lines(); Append to a log, creating folders.

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1. Predict which files are found

Predict the output Easy

Read the code and type exactly what it prints. Names are case-sensitive here. Then press Check to compare.

Read this code 
import os

os.makedirs("shelf", exist_ok=True)
with open("shelf/a.txt", "w") as f:
    f.write("hi")

for name in ["a.txt", "A.txt", "a.txt.txt"]:
    try:
        with open("shelf/" + name) as f:
            f.read()
        print(name, "found")
    except FileNotFoundError:
        print(name, "missing")




  
  

  
  
  



    
  
    

  

    
2. Fix the missing export folder

    Fix the bug
    Easy
    
  

  
This code saves two rows into exports/scores.csv and reads them back into saved, but it raises FileNotFoundError. Fix it so the file is written and saved equals "Asha,90\nBen,75". Keep the shutil.rmtree line, which just resets the demo.

  
    

  

    Your code
    

      
      
      
      
    

  

  
import os
import shutil

shutil.rmtree("exports", ignore_errors=True)   # start clean

rows = ["Asha,90", "Ben,75"]
with open("exports/scores.csv", "w") as f:
    f.write("\n".join(rows))

with open("exports/scores.csv") as f:
    saved = f.read()
print(saved)

  
  
  
  

    
      
      
      
      
    
    
  

  




  
  

  
  
  



    

  
    

  

    
3. Write read_lines()

    Write code
    Medium
    
  

  
Write read_lines(path) that returns the lines of the text file as a list of strings without trailing newlines. If the file does not exist, return an empty list instead of raising. Catch FileNotFoundError only.

  
    

  

    Your code
    

      
      
      
      
    

  

  
def read_lines(path):
    with open(path) as f:
        return f.read().splitlines()

print(read_lines("nothing_here.txt"))

  
  
  
  

    
      
      
      
      
    
    
  

  




  
  

  
  
  



    
  
    

  

    
4. Append to a log, creating folders

    Write code
    Hard
    
  

  
Write append_log(path, message) that adds message plus a newline to the end of the file at path, creating the file and any missing parent folders if needed. Return the number of lines in the file after appending. It must also work for a plain filename with no folder, like "plain.log".

  
    

  

    Your code
    

      
      
      
      
    

  

  
def append_log(path, message):
    with open(path, "a") as f:
        f.write(message + "\n")

append_log("logs/app/run.log", "start")

  
  
  
  

    
      
      
      
      
    
    
  

  




  
  

  
  
  



    
  
  

    Next lessonPython UnboundLocalError
    
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