Answer to Question #101080 in Python for rishabh jain

Question

Describe how catching exceptions can help with file errors. Write three Python examples that actually generate file errors on your computer and catch the errors with try: except: blocks.Describe how you might deal with each error if you were writing a large production program.

Answer 1

1. FileNotFoundError

raised when a file or directory is requested but doesn’t exist. Corresponds to errno ENOENT.

Describe -- I would do the same as in the code, check and ask the user to create a file or not

try:

file_name = 'some_missing_file'

with open(file_name) as f:

print(f)

except FileNotFoundError:

print(f'File: {file_name} not found')

choose = input(f'Create file {file_name} y/n \n')

if choose == 'y':

with open(file_name, 'w') as f:

print(f'File: {f} write')

else:

exit('Bye!')

2. Exception FileExistsError

Raised when trying to create a file or directory which already exists. Corresponds to errno EEXIST.

Describe -- I would do the same as in the code, check and ask the user to overwrite the file or not

import os

try:

file_name = 'some_missing_file'

os.mkdir('./some_missing_file')

except FileExistsError:

print(f'File: some_missing_file exists')

choose = input('Rewrite y/n')

if choose == 'y':

with open(file_name, 'w') as f:

print(f'File: {f} rewrite')

3. PermissionError

Raised when trying to run an operation without the adequate access rights - for example filesystem permissions.

Corresponds to errno EACCES and EPERM.

Describe -- Basically, such an error appears if not an experienced user is trying to remove or modify something, or if someone wants to read a file that should not be with this error, I don’t see the point of fighting as they only help from unnecessary actions, but as a last resort, the user can contact the system administrator

import os

try:

os.mkdir('admin_data', 000)

with open('admin_data') as f:

print(f)

except PermissionError:

print('Access denied \n'

'Ask your system administrator')