The correct fix is to change `{0:s}` to `{0:d}` because the format specifier `s` is designed for string arguments, while `42` is an integer, causing the `ValueError: Unknown format code 's' for object of type 'int'`. In Python’s string formatting, each format specifier must match the data type of the supplied value—`d` stands for decimal integer, whereas `s` expects a string. On the PCAP exam, this question tests your understanding of format specifiers and type compatibility, a common trap where learners mistakenly assume `s` works for any value. A reliable memory tip is to think of `d` as “digit” for integers and `s` as “string” for text; when you see an integer, always reach for `d`, not `s`.
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.
A developer encounters an error: `ValueError: Unknown format code 's' for object of type 'int'` when running `print("{0:s}".format(42))`. What is the problem and how should it be fixed?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Change `{0:s}` to `{0:d}` because the value is an integer, not a string.
Option D is correct because the format specifier `s` in `{0:s}` expects a string argument, but the provided argument `42` is an integer. The `d` format specifier is designed for integers, so changing `{0:s}` to `{0:d}` resolves the `ValueError` by matching the format code to the data type.
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.
✗
Change `{0:s}` to `{0:str}` to explicitly specify string conversion.
Why it's wrong here
`str` is not a format code; use `s` for strings, but the value is int.
✗
Wrap 42 in str(): `print("{0:s}".format(str(42)))`
Why it's wrong here
That would work but is not the most direct fix; the problem is the format code, not the value.
✗
Change `{0:s}` to `{0:i}` to indicate integer.
Why it's wrong here
`i` is not a valid format code; use `d`.
✓
Change `{0:s}` to `{0:d}` because the value is an integer, not a string.
Why this is correct
`d` is the correct format code for decimal integers.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Python Institute often tests the distinction between format specifiers `s` and `d`, trapping candidates who think `s` can handle any type or who confuse `i` (from other languages like C) with Python's `d` for integers.
Detailed technical explanation
How to think about this question
Python's `str.format()` method uses a mini-language where format specifiers like `s` (string) and `d` (decimal integer) are defined in PEP 3101. The `s` specifier calls `str()` on the argument, but it first checks the type and raises `ValueError` if the argument is not a string or a subclass thereof. In real-world code, mismatched format specifiers often occur when dynamically generating format strings or when refactoring code without updating format codes, leading to runtime errors that are easy to miss without testing.
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.
TExam Day Tips
→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 media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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: Change `{0:s}` to `{0:d}` because the value is an integer, not a string. — Option D is correct because the format specifier `s` in `{0:s}` expects a string argument, but the provided argument `42` is an integer. The `d` format specifier is designed for integers, so changing `{0:s}` to `{0:d}` resolves the `ValueError` by matching the format code to the data type.
What should I do if I get this PCAP question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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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