While Loops

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Date:

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Quick Questions

Shade in the A or B circle for each question.

1. When does a while loop stop?

A After 10 times

B When the condition becomes False

2. i=0\nwhile i<3:\n print(i)\n i=i+1\nWhat prints?

A 0, 1, 2

B 1, 2, 3

3. What happens with while True: and no break?

A The loop runs forever

B It runs once

4. What does the condition in a while loop check?

A Whether to keep looping

B How many times to loop

5. count=5\nwhile count>0:\n print(count)\n count=count-1\nWhat prints first?

A 0

B 5

Match the Pairs

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

Left column		Right column
1while x < 10 x += 1		AOutput: 8
2i = 0 while i < 5: print(i)		BOk: Infinite loop with break
3i = 0 while i < 3: i += 1		CValid: Loop runs 3 times
4while True: if done: break		DOutput: 1 2 3
5i = 1 while i <= 3: print(i) i += 1		EError: Infinite loop — never increments i
6x = 10 while x > 8: x -= 1 print(x)		FError: Missing colon after while

Definitions

while

Fill in the Blanks

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

i = 0 _____ i < 5: print(i) i = i + 1

i = 0 while i < 5_ print(i) i = i + 1

i = 0 while i _ 5: print(i) i = i + 1

i = 0 while i < 5: print(i) i = i _ 1

count = 3 while count _ 0: print(count) count = count - 1

Spot the Error

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

Question 1

A i = 0

B while i < 5:

C print(i)

D i = i + 1

Question 2

A i = 0

B while i < 5

C print(i)

D i = i + 1

Question 3

A i = 0

B while i < 5:

C print(i)

D # missing i = i + 1

Question 4

A i = 0

B While i < 5:

C print(i)

D i = i + 1

Question 5

A i = 0

B while i < 5:

C print(i)

D i = i + 1

E print('Done')

Answer Key

While Loops

Section A: Quick Questions

B — When the condition becomes False

A — 0, 1, 2

A — The loop runs forever

A — Whether to keep looping

B — 5

Section B: Match the Pairs

while x < 10 x += 1 → Error: Missing colon after while

i = 0 while i < 5: print(i) → Error: Infinite loop — never increments i

i = 0 while i < 3: i += 1 → Valid: Loop runs 3 times

while True: if done: break → Ok: Infinite loop with break

i = 1 while i <= 3: print(i) i += 1 → Output: 1 2 3

x = 10 while x > 8: x -= 1 print(x) → Output: 8

Section C: Definitions

while — Repeats indented code as long as the condition is True.~~Condition

Section D: Fill in the Blanks

i = 0
while i < 5:
    print(i)
    i = i + 1

i = 0
while i < 5:
    print(i)
    i = i + 1

i = 0
while i < 5:
    print(i)
    i = i + 1

i = 0
while i < 5:
    print(i)
    i = i + 1

count = 3
while count > 0:
    print(count)
    count = count - 1

Section E: Spot the Error

C — Code inside the while loop must be indented

B — Missing colon at the end of the while line

C — Missing i = i + 1: the counter never increases, causing an infinite loop

B — while must be lowercase: While is not valid Python

E — 'Done' is indented inside the loop it prints 5 times instead of once