Error Handling – try/except basics

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Quick Questions

Shade in the A or B circle for each question.

1. What does try/except do?

A Catches errors so the program doesn't crash

B Makes code faster

2. What goes inside the try block?

A Error messages

B Code that might cause an error

3. When does the except block run?

A Always

B Only when an error occurs in try

4. try:\n int('abc')\nexcept:\n print('Oops')\nWhat prints?

A Oops

B abc

5. try:\n print(5 + 3)\nexcept:\n print('Error')\nWhat prints?

A 8

B Error

Match the Pairs

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

Left column		Right column
1try: x = int('abc') exept: print('oops')		AOutput: error
2except: print('error') try: risky()		BValid: Catches ValueError only
3try: x = int(val) except ValueError: print('bad')		COutput: 5
4try: risky() except: print('handled')		DError: Typo — 'except' not 'exept'
5try: print(int('hi')) except: print('error')		EError: try must come before except
6try: print(int('5')) except: print('error')		FOk: Catches any error

Definitions

try

Fill in the Blanks

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

___: num = int(input('Number: ')) except: print('Invalid')

try: num = int(input('Number: ')) ______: print('Invalid')

try: num = int(input('Number: ')) except __________: print('Not a number')

try: result = 10 / _ except: print('Error')

try: x = ___(input('Enter num: ')) except: print('Bad input')

Spot the Error

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

Question 1

A try

B num = int(input('Number: '))

C except:

D print('Invalid')

Question 2

A try:

B num = int(input('Number: '))

C except

D print('Invalid')

Question 3

A try:

B num = int(input('Number: '))

C except:

D print('Invalid')

Question 4

A except:

B print('Invalid')

C print('Try again')

D print('Done')

Question 5

A Try:

B num = int('abc')

C Except:

D print('Error')

Answer Key

Error Handling – try/except basics

Section A: Quick Questions

A — Catches errors so the program doesn't crash

B — Code that might cause an error

B — Only when an error occurs in try

A — Oops

A — 8

Section B: Match the Pairs

try: x = int('abc') exept: print('oops') → Error: Typo — 'except' not 'exept'

except: print('error') try: risky() → Error: try must come before except

try: x = int(val) except ValueError: print('bad') → Valid: Catches ValueError only

try: risky() except: print('handled') → Ok: Catches any error

try: print(int('hi')) except: print('error') → Output: error

try: print(int('5')) except: print('error') → Output: 5

Section C: Definitions

try — Block containing code that might cause an error.~~except

Section D: Fill in the Blanks

try:
    num = int(input('Number: '))
except:
    print('Invalid')

try:
    num = int(input('Number: '))
except:
    print('Invalid')

try:
    num = int(input('Number: '))
except ValueError:
    print('Not a number')

try:
    result = 10 / 0
except:
    print('Error')

try:
    x = int(input('Enter num: '))
except:
    print('Bad input')

Section E: Spot the Error

A — Missing colon after try

C — Missing colon after except

B — Code inside try must be indented

A — except cannot stand alone: it must follow a try block

A — try and except must be lowercase