while True pattern in Python - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of a simple while True loop with break

What is the output of this code?

Python

count = 0
while True:
    print(count)
    count += 1
    if count == 3:
        break

A

0
1
2
3
4

B

0
1
2
3

C

1
2
3

D

0
1
2

💡 Hint

The loop stops when count reaches 3, so it prints before breaking.

The loop starts at 0 and prints count each time. When count becomes 3, the break stops the loop before printing 3.

❓ Predict Output

intermediate

While True loop with continue and break

What is the output of this code?

Python

i = 0
while True:
    i += 1
    if i == 2:
        continue
    if i == 4:
        break
    print(i)

A

1
2
3

B

1
3

C

1
3
4

D

2
3

💡 Hint

The continue skips printing when i is 2.

When i is 2, continue skips the print. The loop breaks at i == 4, so 4 is not printed. Only 1 and 3 are printed.

🔧 Debug

advanced

Identify the error in this while True loop

What error does this code raise when run?

Python

while True
    print("Hello")
    break

A SyntaxError

B IndentationError

C NameError

D No error, prints Hello once

💡 Hint

Check the syntax of the while statement.

The while statement is missing a colon at the end, causing a SyntaxError.

❓ Predict Output

advanced

Output of nested while True loops with break

What is the output of this code?

Python

x = 0
while True:
    y = 0
    while True:
        print(f"{x},{y}")
        y += 1
        if y == 2:
            break
    x += 1
    if x == 3:
        break

A

0,0
1,0
2,0

B

0,0
0,1
0,2
1,0
1,1
2,0
2,1

C

0,0
0,1
1,0
1,1
2,0
2,1

D

0,0
0,1
1,0
1,1
2,0

💡 Hint

Inner loop runs twice for each outer loop iteration.

The inner loop prints y from 0 to 1, then breaks. The outer loop runs x from 0 to 2, then breaks.

🧠 Conceptual

expert

Why use while True with break instead of a condition?

Which is the best reason to use a while True loop with a break inside instead of a while loop with a condition?

A To handle complex exit conditions inside the loop body more clearly

B To create an infinite loop that never stops

C Because while True loops run faster than while with conditions

D To avoid indentation errors

💡 Hint

Think about readability and control inside the loop.

Using while True with break allows placing multiple exit points inside the loop, making complex conditions easier to manage.

Practice

1.

What does the while True loop do in Python?

easy

A. It creates a loop that runs forever unless stopped by break.

B. It runs the loop only once.

C. It runs the loop a fixed number of times.

D. It causes a syntax error.

Solution

1. Step 1: Understand the meaning of while True

   The condition True is always true, so the loop will keep running forever.

2. Step 2: Recognize how to stop the loop

   To stop this infinite loop, a break statement is used inside the loop when a condition is met.

3. Final Answer:

   It creates a loop that runs forever unless stopped by break. -> Option A

4. Quick Check:

   while True = infinite loop until break [OK]

Hint: Remember: while True loops forever until break stops it [OK]

Common Mistakes:

• Thinking it runs only once
• Assuming it runs a fixed number of times
• Believing it causes a syntax error

2.

Which of the following is the correct syntax to stop a while True loop when a variable count reaches 5?

count = 0
while True:
    count += 1
    ?

easy

A. if count == 5: break

B. if count = 5: break

C. if count == 5: continue

D. if count > 5: stop

Solution

1. Step 1: Identify correct comparison operator

   Use == to compare values, so if count == 5 is correct.

2. Step 2: Use break to exit the loop

   The break statement stops the loop immediately when the condition is true.

3. Final Answer:

   if count == 5: break -> Option A

4. Quick Check:

   Use == and break to stop loop [OK]

Hint: Use double equals (==) for comparison and break to stop [OK]

Common Mistakes:

• Using single equals (=) instead of double equals (==)
• Using continue instead of break
• Using undefined commands like stop

3.

What will be the output of the following code?

i = 0
while True:
    i += 2
    if i > 6:
        break
print(i)

medium

A. 0

B. 6

C. 4

D. 8

Solution

1. Step 1: Trace the loop increments

   i starts at 0, then increases by 2 each loop: 2, 4, 6, 8.

2. Step 2: Check the break condition

   The loop breaks when i > 6, which happens when i becomes 8.

3. Final Answer:

   6 -> Option B

4. Quick Check:

   Loop stops at i=8 because 8 > 6, but the printed value is the last before break, which is 6 [OK]

Hint: Add increments step-by-step until break condition met [OK]

Common Mistakes:

• Stopping at i=6 instead of i=8
• Printing before break
• Confusing break condition with >= instead of >

4.

Find the error in this code snippet:

count = 0
while True
    count += 1
    if count == 3:
        break
print(count)

medium

A. Wrong comparison operator in if count == 3

B. Incorrect indentation of count += 1

C. Missing break statement

D. Missing colon after while True

Solution

1. Step 1: Check syntax of while statement

   Python requires a colon (:) after while True to start the loop block.

2. Step 2: Verify other parts

   Indentation and comparison operator are correct; break is present.

3. Final Answer:

   Missing colon after while True -> Option D

4. Quick Check:

   Loops need colon after condition [OK]

Hint: Look for missing colons after loop or if statements [OK]

Common Mistakes:

• Forgetting colon after while
• Misaligning indentation
• Confusing = and == in conditions

5.

You want to write a program that keeps asking the user to enter a number until they enter a negative number. Which code snippet correctly uses while True to do this?

hard

A. while num >= 0:
num = int(input('Enter number: '))
print(f'You entered {num}')

B. while True:
num = int(input('Enter number: '))
if num > 0:
break
print(f'You entered {num}')

C. while True:
num = int(input('Enter number: '))
if num < 0:
break
print(f'You entered {num}')

D. while True:
num = input('Enter number: ')
if num < 0:
break

Solution

1. Step 1: Check loop condition and input

   while True: num = int(input('Enter number: ')) if num < 0: break print(f'You entered {num}') uses while True and asks for input inside the loop, converting it to int.

2. Step 2: Verify break condition and output

   It breaks when the number is negative (< 0) and prints the number otherwise.

3. Final Answer:

   while True: num = int(input('Enter number: ')) if num < 0: break print(f'You entered {num}') -> Option C

4. Quick Check:

   Break on negative input inside infinite loop [OK]

Hint: Break loop when negative number entered, print otherwise [OK]

Common Mistakes:

• Breaking on wrong condition (positive instead of negative)
• Not converting input to int
• Missing print statement or break