PCAP Strings Practice Question
What is the result of the expression '12345'[:10]?
⚠ Common exam trap
The PCAP exam often tests the misconception that slicing beyond the string length causes an IndexError or that Python automatically pads the result to the specified length, leading candidates to choose A or C instead of recognizing the graceful truncation.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
'12345'
In Python, slicing a string with a start index of 0 and an end index of 10 (as in '12345'[:10]) returns the entire string if the slice end exceeds the string length. Since '12345' has only 5 characters, the slice extracts all characters without padding or error, resulting in '12345'.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
'12345 '
Why it's wrong here
Padding the string to ten places with spaces is a formatting behavior, not a slicing behavior. Slicing returns a substring of the original object and never inserts filler characters to satisfy a requested stop value. To obtain '12345 ' one would need an explicit method such as '12345'.ljust(10), not a slice.
- ✓
'12345'
Why this is correct
The expression slices the string literal '12345' with a stop index that exceeds the string's length. Python's slice operation clamps out-of-range boundaries to the sequence's actual length, so it returns every character from index 0 through index 4. Thus the result is exactly the original five-character string '12345', with no error and no added whitespace.
- ✗
IndexError
Why it's wrong here
IndexError would only be raised by direct subscription such as '12345'[10], where a single integer index outside the valid range is looked up. A slice uses a range of indices and Python silently clamps the endpoint to the length of the string, so '12345'[0:10] is perfectly legal. The slice protocol is deliberately forgiving about out-of-range bounds, unlike integer indexing, which is strict.
- ✗
'12345 '
Why it's wrong here
A trailing space would mean the slice produced '12345 ' — a six-character result. Slicing extracts a contiguous existing substring; it never synthesizes or appends characters that are not already present in the original sequence. Since the source string '12345' contains no space character, no slice boundary combination can yield one.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.