The answer is all(c in '0123456789abcdefABCDEF' for c in s). This expression works by iterating over every character in the string s and checking whether each one belongs to the explicit set of valid hexadecimal digits, returning True only if every character passes the test. The technical concept here is membership testing within a string of allowed characters, which is both precise and efficient because it avoids relying on broader methods like isalnum() or isdigit(), which would incorrectly accept non-hexadecimal letters or fail on uppercase hex digits. On the Certified Associate Python Programmer PCAP exam, this question tests your understanding of the all() function combined with generator expressions, a common pattern for validating string content. A frequent trap is assuming isdigit() or isxdigit() (which doesn’t exist in standard Python) will work, but the exam expects you to know the explicit character set approach. Memory tip: think “all hex in one string” — the valid hex digits are just 0-9, a-f, and A-F, so check every character against that single literal.
PCAP Strings Practice Question
This PCAP practice question tests your understanding of strings. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Which of the following expressions returns True if the string s contains only hexadecimal digits (0-9, a-f, A-F)?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
all(c in '0123456789abcdefABCDEF' for c in s)
The most reliable way is to check each character against a set of valid hex digits. Option C does exactly that. Other options are too broad or incorrect.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
s.isdigit() or s.isalpha()
Why it's wrong here
Incorrect: This allows any digit or any letter, including non-hex like 'g'.
✗
s.isnumeric()
Why it's wrong here
Incorrect: isnumeric() only checks for numeric characters, not letters.
✗
s.isalnum() and s.islower()
Why it's wrong here
Incorrect: isalnum() allows digits and letters, but islower() restricts to lowercase, missing uppercase hex.
✓
all(c in '0123456789abcdefABCDEF' for c in s)
Why this is correct
Correct: Checks each character against the set of valid hex digits.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
Use explanations to understand the rule behind the answer.
TExam Day Tips
→Underline the problem statement mentally.
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
What to study next
Got this wrong? Here's your next step.
Identify which PCAP exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Strings — This question tests Strings — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: all(c in '0123456789abcdefABCDEF' for c in s) — The most reliable way is to check each character against a set of valid hex digits. Option C does exactly that. Other options are too broad or incorrect.
What should I do if I get this PCAP question wrong?
Identify which PCAP exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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This PCAP practice question is part of Courseiva's free Python Institute certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the PCAP exam.
Question Discussion
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