PCAP Strings Practice Test 10 — 15 Questions

Question 1

A developer needs to parse a log file where each line contains a timestamp followed by a message. The timestamp format is 'YYYY-MM-DD HH:MM:SS'. Which string method is most appropriate to split the timestamp from the message?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

str.split(). Str.split(), is the most appropriate because it splits a string on whitespace by default. Although the timestamp 'YYYY-MM-DD HH:MM:SS' contains a space, using split() without arguments returns a list of all space-separated elements. Since the timestamp is always the first two elements (date and time), the developer can join them with a space to get the full timestamp. Alternatively, split() can be used with a specified separator and maxsplit to achieve the desired split. This flexibility makes str.split() the best choice among the given options.

Answer

str.rsplit()

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str.splitlines()

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str.partition()

Question 2

A programmer writes a function that expects a string and returns it reversed. Which code snippet correctly reverses the string 'stressed' to 'desserts'?

Accepted Answer

result = s[::-1]. Both option B and option D correctly reverse the string 'stressed' to 'desserts'. Option B uses slice notation `[::-1]`, which creates a reversed copy of the string by stepping from end to start with a step of -1. This is the most direct and idiomatic way to reverse a string in Python. Option D uses `''.join(reversed(s))`: `reversed(s)` returns an iterator that yields characters in reverse order, and `join()` concatenates them into a new string. This is also a valid and correct approach. Option A is incorrect because strings do not have a `reversed()` method; `reversed()` is a built-in function. Option C is incorrect because `.reverse()` is a list method, not a string method, and strings are immutable.

Answer

result = s.reversed()

Answer

s.reverse()

Question 3

A developer is tasked with validating user input that must be a 10-digit phone number. The input may contain spaces, dashes, and parentheses. Which approach best ensures the input contains exactly 10 digits?

Accepted Answer

if len([c for c in s if c.isdigit()]) == 10:. Uses a list comprehension to filter only digit characters from the input string `s` and then checks if the count of those digits is exactly 10. This correctly handles any non-digit characters (spaces, dashes, parentheses) by ignoring them, ensuring the validation focuses solely on the presence of exactly ten digits.

Answer

if len(s) >= 10 and s.isdigit():

Answer

if s[:10].isdigit():

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if s.isdigit() and len(s) == 10:

Question 4

A developer needs to check if a string contains only alphanumeric characters. Which string method should be used?

Accepted Answer

s.isalnum(). The `isalnum()` method returns `True` if all characters in the string are alphanumeric (letters or digits) and the string is non-empty. This directly matches the requirement to check for only alphanumeric characters, covering both letters and digits without any other characters.

Answer

s.isnumeric()

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s.isdigit()

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s.isalpha()

Question 5

Which THREE of the following are valid ways to create a string in Python?

Accepted Answer

'world'. All five options are valid ways to create a string in Python. 'world' (A) is a single-quoted string literal, str(['h','i']) (B) uses the str() constructor to convert a list into its string representation ''['h', 'i']'', '''multi-line''' (C) is a triple-quoted string literal, str(None) (D) converts the None object into the string 'None', and 'hello' (E) is a double-quoted string literal. The str() function returns a string for any argument, making B and D just as valid as the literals A, C, and E.

Question 6

You are a developer at a company that processes customer feedback. Each feedback entry is stored as a string containing a rating (1-5) followed by a colon and then the comment. For example: '4: Great service'. You need to extract only the comments from feedback that have a rating of 4 or 5. You have a list of feedback strings. Which code snippet correctly implements this?

Accepted Answer

[s.split(':')[1].strip() for s in feedback if s.split(':')[0].strip() in ('4','5')]. It splits each feedback string on ':', extracts the comment (index [1]), strips whitespace, and filters only those entries where the rating (index [0], stripped) is exactly '4' or '5'. This ensures only comments from high-rated feedback are collected, handling potential spaces around the colon.

Answer

[s for s in feedback if s.startswith('4') or s.startswith('5')]

Answer

[s.split(':') for s in feedback][1]

Answer

[s.split(':')[1] for s in feedback if '4' in s or '5' in s]

Question 7

A logging module receives a message that may contain sensitive data. To comply with data privacy, all digits in the message should be replaced with 'X' before logging. Which approach correctly achieves this?

Accepted Answer

re.sub(r'[0-9]', 'X', message). Options B, C, and D all correctly replace all digits in the message with 'X'. Option B uses `re.sub()` with a regex character class to match any digit. Option C uses `str.translate()` with a mapping from each digit to 'X', which works because the mapping explicitly covers all digits. Option D uses a list comprehension with `isdigit()` to conditionally replace digits. Option A is incorrect because `str.replace()` does not interpret character ranges; it would look for the literal string '0-9'. Therefore, three correct approaches exist.

Answer

message.replace('0-9', 'X')

Question 8

A data pipeline processes CSV lines that may contain quoted fields with commas inside double quotes. For example: 'John, "Doe, Jr.", 35'. The team needs to split such a line correctly. Which approach is best?

Accepted Answer

Use csv.reader([line]) to parse the line.. Python's `csv.reader` is specifically designed to handle CSV parsing according to RFC 4180, including quoted fields that contain commas, newlines, and embedded quotes. It automatically manages quote state and field boundaries, making it the most robust and Pythonic solution for this task.

Answer

Manually iterate over characters and track quote state.

Answer

Use str.split(',') after removing all quotes.

Answer

Use re.split(r',(?=(?:[^"]*"[^"]*")*[^"]*$)', line)

Question 9

Which TWO of the following string methods modify the string in place? (Note: Python strings are immutable.)

Accepted Answer

str.lower(). None of the listed string methods modify the string in place because Python strings are immutable. All string methods return a new string rather than altering the original. Therefore, there are no correct options for this question.

Answer

str.join()

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str.replace()

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str.strip()

Question 10

You are a developer for an e-commerce platform. The system receives product descriptions from suppliers in various formats. One supplier sends descriptions with inconsistent capitalization, extra whitespace, and occasional leading/trailing punctuation. Your task is to write a function that normalizes these descriptions: convert to lowercase, remove leading/trailing whitespace and punctuation (.,!?;:), and replace multiple spaces with a single space. The function should return the cleaned string. Which implementation correctly performs all these steps?

Accepted Answer

def normalize(s): import re; s = s.strip(); s = s.strip('.,!?;:'); s = s.lower(); s = re.sub(r'\s+', ' ', s); return s. It performs all required steps in the correct order: it first strips leading/trailing whitespace with `strip()`, then removes leading/trailing punctuation using `strip('.,!?;:')`, converts to lowercase with `lower()`, and finally replaces multiple spaces with a single space using `re.sub(r'\s+', ' ', s)`. This ensures that punctuation is removed only from the edges after whitespace is handled, and internal whitespace is normalized last.

Answer

def normalize(s): return ' '.join(s.lower().split())

Answer

def normalize(s): return s.lower().strip('.,!?;: ')

Answer

def normalize(s): return s.strip().lower()

Question 11

Drag and drop the steps to handle an exception in Python using try-except-finally into the correct order.

Accepted Answer

try block, then except block(s), then else block, then finally block. Exception handling follows the order: try block, except blocks, else block, finally block. The raise statement can be used anywhere to trigger an exception.

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try block, then except block(s), then finally block, then else block

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try block, then else block, then except block(s), then finally block

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else block, then try block, then except block(s), then finally block

Question 12

Match each exception to its cause.

Accepted Answer

ValueError: Raised when a built-in operation or function receives an argument that has the right type but an inappropriate value.. Correct matches: ValueError with inappropriate value, TypeError with wrong type, IndexError with out-of-range index, KeyError with missing key. Common confusions arise from swapping the definitions of ValueError and TypeError, or TypeError and KeyError.

Answer

ValueError: Raised when an operation or function is applied to an object of inappropriate type.

Answer

TypeError: Raised when a mapping key is not found in the set of existing keys.

Question 13

A developer wants to check if a string ends with a specific suffix. Which method should be used?

Accepted Answer

endswith(). The `endswith()` method is specifically designed to check if a string ends with a given suffix, returning a boolean value. This is the correct and most direct approach for the task described, as it avoids manual slicing or comparison.

Answer

index()

Answer

find()

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startswith()

Question 14

A developer writes: s = 'abc'; s[0] = 'x'. What happens?

Accepted Answer

TypeError: 'str' object does not support item assignment. In Python, strings are immutable, meaning their contents cannot be changed after creation. Attempting to assign a new character to an index position (e.g., `s[0] = 'x'`) raises a `TypeError: 'str' object does not support item assignment`. This is a fundamental property of the `str` type in Python, enforced at the interpreter level.

Answer

s becomes 'xbc'

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ValueError: string index out of range

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s becomes 'abc' and no error

Question 15

Given s = 'a1b2c3', which TWO of the following expressions return the string '123'?

Accepted Answer

s[1::2]. Slicing with `s[1::2]` starts at index 1 (the character '1'), goes to the end of the string, and takes every second character, resulting in '1', '2', '3' concatenated as '123'. Option C is also correct because `s[1:6:2]` starts at index 1, stops before index 6 (the string length is 6, so index 6 is just past the last character), and steps by 2, yielding the same sequence of characters.

Answer

s[0:5:2]

Answer

s[0::2]

Answer

s[2:5:1]