PCEP Control Flow, Loops, Lists and Logic Practice Question

A validation script defines a list named flags containing boolean values. The script must determine whether every flag is True and print 'All clear' only in that case; otherwise it should print 'Check needed'. Which code fragment implements this logic correctly?

⚠ Common exam trap

Candidates often confuse any with all or assuming that a non-empty list of booleans is itself a reliable truth test for all values being True.

Answer choices

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Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.

Correct answer & explanation

✓

if all(flags): print('All clear') else: print('Check needed')

Determining that every element is True requires a check that inspects all elements and fails if any is falsy. The built-in all function does exactly that, returning True only when every element is truthy and False otherwise, which maps directly onto the two required messages.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

✗
if flags: print('All clear') else: print('Check needed')
Why it's wrong here
Using the list itself as a condition tests only whether the list is non-empty. A list containing False values is still non-empty and therefore truthy, so the script would incorrectly print 'All clear' even when some flags are False.
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if any(flags): print('All clear') else: print('Check needed')
Why it's wrong here
The any function returns True when at least one element is truthy, not when all are. A list containing a single True and several False values would incorrectly print 'All clear', so this fragment does not enforce the requirement that every flag be True.
✓
if all(flags): print('All clear') else: print('Check needed')
Why this is correct
The built-in all function returns True when every element in the iterable is truthy. For a list of booleans, that means all values must be True, so the conditional prints the correct message for both the all-True and any-False cases.
✗
if flags == True: print('All clear') else: print('Check needed')
Why it's wrong here
Comparing a list to the boolean True with == is always False because a list and a boolean are different types. The condition never succeeds, so the script always prints 'Check needed' regardless of the contents of flags.

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PCEP Control Flow, Loops, Lists and Logic Practice Question

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