While–else behavior in Python - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the else block do in a while–else statement?

The else block runs only if the while loop finishes normally without encountering a break statement.

beginner

When is the else block skipped in a while–else loop?

The else block is skipped if the while loop exits early due to a break statement.

beginner

Consider this code:<br>

i = 0
while i < 3:
    print(i)
    i += 1
else:
    print('Done')

<br>What will be printed?

The output will be:<br>0<br>1<br>2<br>Done<br>The else runs because the loop finished normally.

beginner

What happens if a break is used inside a while loop with an else?

If break runs, the loop stops immediately and the else block does not run.

intermediate

Why might you use a while–else instead of just a while loop?

You use while–else to run special code only if the loop did not stop early, like confirming a search found nothing.

What triggers the else block in a while–else loop?

A The loop contains a break

B The loop runs at least once

C The loop finishes without a break

D The loop condition is false initially

The else block runs only if the loop finishes normally without a break.

If a while loop never runs because the condition is false at start, does the else block run?

A Yes, because the loop did not break

B No, never

C Yes, always

D Only if there is a break

The else block runs if the loop condition is false initially and the loop body never executes.

What happens if a break is inside the while loop?

A The <code>else</code> block runs after break

B The <code>else</code> block is skipped

C The loop restarts

D The program crashes

A break stops the loop early and skips the else block.

Which of these is a good use of while–else?

A To run code only if the loop breaks

B To run code before the loop starts

C To run code inside the loop

D To run code after a loop that found no matching item

while–else is useful to run code if the loop completes without finding something.

What will this code print?<br>

i = 0
while i < 5:
    if i == 3:
        break
    print(i)
    i += 1
else:
    print('Finished')

A 0 1 2

B 0 1 2 Finished

C Finished

D 0 1 2 3 4 Finished

The loop breaks at i == 3, so else does not run. It prints 0,1,2 only.

Explain how the else block works with a while loop in Python.

Think about when the loop ends normally versus early.

Describe a real-life example where a while–else loop would be helpful.

Imagine looking for your keys and what you do if you find or don't find them.