Files – Error Handling (try/except)

Name:

Date:

Class:

Quick Questions

Shade in the A or B circle for each question.

1. What error occurs when reading a missing file?

A FileNotFoundError

B ValueError

2. Why use try/except with files?

A Files might not exist or be inaccessible

B It makes code faster

3. What does 'finally' do?

A Only runs on error

B Always runs, even if there's an error

4. Which is safer: try/except or with?

A Both together is safest

B try/except alone

5. What error if you can't write to a file?

A WriteError

B PermissionError

Match the Pairs

Draw a line connecting each item on the left to its match on the right.

Left column		Right column
1open('missing.txt')		AOutput: Missing
2try: f = open('f.txt') except: pass f.read()		BValid: Handle missing file
3try: f = open('f.txt') except FileNotFoundError: print('Not found')		COutput: FileNotFoundError
4try: open('f.txt') finally: print('done')		DError: f may not be defined
5try: open('x.txt') except FileNotFoundError: print('Missing')		EError: FileNotFoundError
6try: open('x.txt') except Exception as e: print(type(e).__name__)		FOk: finally always runs

Definitions

FileNotFoundError

Fill in the Blanks

Complete each line of code by filling in the missing parts.

try: with open('f.txt') as f: print(f.read()) except _________________: print('Not found')

try: with open('f.txt') as f: print(f.read()) except Exception __ e: print(e)

___: f = open('f.txt') except FileNotFoundError: print('Missing')

try: with open('f.txt') as f: print(f.read()) except _______________: print('No access')

try: open('f.txt') except FileNotFoundError: print('Missing') _______: print('Done')

Spot the Error

Shade in the letter of the line that contains an error.

Question 1

A try

B with open('f.txt') as f:

C print(f.read())

D except FileNotFoundError:

E print('Missing')

Question 2

A try:

B with open('f.txt') as f:

C print(f.read())

D except filenotfounderror:

E print('Missing')

Question 3

A except:

B print('Error')

C try:

D with open('f.txt') as f:

E print(f.read())

Question 4

A try:

B with open('f.txt') as f:

C print(f.read())

D catch FileNotFoundError:

E print('Missing')

Question 5

A try:

B with open('f.txt') as f:

C print(f.read())

D except:

E pass # silently ignore

Answer Key

Files – Error Handling (try/except)

Section A: Quick Questions

A — FileNotFoundError

A — Files might not exist or be inaccessible

B — Always runs, even if there's an error

A — Both together is safest

B — PermissionError

Section B: Match the Pairs

open('missing.txt') → Error: FileNotFoundError

try: f = open('f.txt') except: pass f.read() → Error: f may not be defined

try: f = open('f.txt') except FileNotFoundError: print('Not found') → Valid: Handle missing file

try: open('f.txt') finally: print('done') → Ok: finally always runs

try: open('x.txt') except FileNotFoundError: print('Missing') → Output: Missing

try: open('x.txt') except Exception as e: print(type(e).__name__) → Output: FileNotFoundError

Section C: Definitions

FileNotFoundError — Error when trying to read a file that doesn't exist.~~PermissionError

Section D: Fill in the Blanks

try:
    with open('f.txt') as f:
        print(f.read())
except FileNotFoundError:
    print('Not found')

try:
    with open('f.txt') as f:
        print(f.read())
except Exception as e:
    print(e)

try:
    f = open('f.txt')
except FileNotFoundError:
    print('Missing')

try:
    with open('f.txt') as f:
        print(f.read())
except PermissionError:
    print('No access')

try:
    open('f.txt')
except FileNotFoundError:
    print('Missing')
finally:
    print('Done')

Section E: Spot the Error

A — Missing colon after try

D — Error names are capitalized: FileNotFoundError

A — try must come before except

D — Python uses except, not catch

E — Bare except with pass silently hides ALL errors. Catch specific errors.