PCAP Strings Practice Test 5 — 15 Questions

Question 1

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?

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

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 2

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 3

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()

Answer

str.replace()

Answer

str.strip()

Question 4

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 5

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.

Answer

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

Answer

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

Answer

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

Question 6

Drag and drop the steps to debug a Python script using pdb into the correct order.

Accepted Answer

Step 1: Start the pdb debugger. Step 2: Run the script. Step 3: Step through the code. Step 4: Inspect variables. Step 5: Exit the debugger.. Debugging with pdb involves setting a trace, running the script, using commands to step through code, setting breakpoints, and exiting.

Answer

Step 1: Start the pdb debugger. Step 2: Inspect variables. Step 3: Step through the code. Step 4: Run the script. Step 5: Exit the debugger.

Answer

Step 1: Run the script. Step 2: Start the pdb debugger. Step 3: Step through the code. Step 4: Inspect variables. Step 5: Exit the debugger.

Answer

Step 1: Start the pdb debugger. Step 2: Step through the code. Step 3: Run the script. Step 4: Inspect variables. Step 5: Exit the debugger.

Question 7

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 8

Match each string method to its purpose.

Accepted Answer

upper(): Converts all characters to uppercase.. The correct matches are: .upper() converts to uppercase, .lower() converts to lowercase, .strip() removes leading/trailing whitespace. Common confusions include swapping .split() and .replace(), and confusing .replace() with .upper().

Answer

split(): Replaces all occurrences of a substring with another.

Answer

join(): Splits the string into a list of substrings.

Answer

replace(): Converts all characters to uppercase.

Question 9

Match each variable scope to its description.

Accepted Answer

Local: Variables defined inside a function.. The LEGB rule defines scope lookup order: Local, Enclosing, Global, Built-in. Correct matches are Local (inside function), Enclosing (outer function), Global (module level). Built-in consists of Python's predefined names.

Answer

Built-in: Variables defined at the top level of a module.

Answer

Local: Variables defined in an enclosing function.

Answer

Global: Predefined names like print and len.

Question 10

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()

Answer

startswith()

Question 11

Which of the following expressions returns the string 'Hello' repeated three times?

Accepted Answer

'Hello' * 3. In Python, the multiplication operator (*) when used with a string and an integer performs string repetition. 'Hello' * 3 returns the string 'HelloHelloHello' by concatenating three copies of the original string. This is a core feature of Python's sequence protocol, where strings are sequences of characters.

Answer

'Hello' + 3

Answer

'Hello' * '3'

Answer

'Hello' * 3.0

Question 12

What is the result of the expression 'aBc'.lower()?

Accepted Answer

'abc'. The `lower()` method returns a new string with all cased characters converted to lowercase. Since the original string 'aBc' contains an uppercase 'B', calling `.lower()` converts it to 'b', resulting in 'abc'. The method does not modify the original string but returns a new one.

Answer

'Abc'

Answer

'aBc'

Answer

'ABC'

Question 13

What does the expression 'hello world'.title() return?

Accepted Answer

'Hello World'. The `title()` method in Python returns a copy of the string where the first character of each word is converted to uppercase and all remaining characters are converted to lowercase. For the string 'hello world', this results in 'Hello World', making option A correct.

Answer

'HELLO WORLD'

Answer

'Hello world'

Answer

'hello World'

Question 14

Which of the following best describes the immutability of strings in Python?

Accepted Answer

Strings cannot be changed after creation, but variables can be reassigned.. Strings in Python are immutable objects, meaning once a string is created, its contents cannot be changed. However, the variable referencing the string can be reassigned to point to a new string object. This distinction between mutability of the object and reassignment of the variable is fundamental to Python's data model.

Answer

Strings can be modified in place using indexing.

Answer

Strings are mutable but require special methods.

Answer

Strings cannot be reassigned.

Question 15

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'

Answer

ValueError: string index out of range

Answer

s becomes 'abc' and no error