PCAP Strings Practice Test 8 — 15 Questions

Question 1

Which expression returns the last character of string s?

Accepted Answer

s[-1]. Python uses zero-based indexing for strings, where negative indices count from the end. s[-1] directly accesses the last character of the string, as -1 refers to the final element in the sequence.

Answer

s[len(s)]

Answer

s[-0]

Answer

s[0]

Question 2

A programmer has a string s = 'Python programming is fun'. They want to extract the word 'programming'. Which slicing expression achieves this?

Accepted Answer

s[7:18]. Python uses zero-based indexing. The word 'programming' starts at index 7 (the character 'p' in 'programming') and ends at index 17 (the character 'g'), but slicing is exclusive of the end index, so s[7:18] extracts characters from index 7 up to but not including index 18, which gives 'programming'.

Answer

s[6:18]

Answer

s[7:19]

Answer

s[6:19]

Question 3

Which of the following is the correct way to format a string to include a variable value with two decimal places in Python?

Accepted Answer

f"{value:.2f}". Uses the correct f-string format specifier `:.2f`, where `f` stands for fixed-point notation and `.2` specifies two decimal places. This is the standard Python syntax for formatting a floating-point number to two decimal places within an f-string.

Answer

f"{value:.2}"

Answer

f"{value%:.2f}"

Answer

f"{value:2f}"

Question 4

What is the output of the following code? s = 'Hello'; print(s.find('l'))

Accepted Answer

2. The `str.find()` method returns the lowest index of the first occurrence of the substring. In the string 'Hello', the character 'l' first appears at index 2 (0-based indexing: H=0, e=1, l=2). Therefore, `s.find('l')` returns 2, making option B correct.

Answer

1

Answer

0

Answer

3

Question 5

A developer writes a function to reverse a string: def reverse_str(s): return s[::-1]. Which of the following statements about this function is true?

Accepted Answer

It returns a new reversed string. The slice operation `s[::-1]` creates a new string that is the reverse of the original. Strings in Python are immutable, so any operation that appears to modify a string actually returns a new string object. The original string `s` remains unchanged.

Answer

It only works for strings with even length

Answer

It modifies the original string

Answer

It raises an error if s is empty

Question 6

Which of the following expressions returns True if the string s contains only hexadecimal digits (0-9, a-f, A-F)?

Accepted Answer

all(c in '0123456789abcdefABCDEF' for c in s). It explicitly checks each character in the string against the set of valid hexadecimal digits (0-9, a-f, A-F) using the `all()` function. This ensures that every character is a hex digit, which is the precise requirement for a string to contain only hexadecimal digits.

Answer

s.isdigit() or s.isalpha()

Answer

s.isnumeric()

Answer

s.isalnum() and s.islower()

Question 7

What is the result of the expression '123'.zfill(5)?

Accepted Answer

'00123'. The `zfill()` method in Python pads the string on the left with zeros until it reaches the specified width. For the string '123' and width 5, it adds two zeros to the left, resulting in '00123'. This is the correct behavior as defined in Python's string methods.

Answer

'123'

Answer

'000123'

Answer

'12300'

Question 8

Which TWO string methods are used to determine if a string begins or ends with a specified prefix or suffix? (Choose two.)

Accepted Answer

startswith(). The `startswith()` method returns `True` if a string begins with the specified prefix, and `endswith()` returns `True` if a string ends with the specified suffix. Both methods accept a string or a tuple of strings to check against, making them the correct choices for determining prefix or suffix presence.

Answer

count()

Answer

find()

Answer

index()

Question 9

Which THREE of the following string methods can be used to split a string into a list of substrings? (Choose three.)

Accepted Answer

splitlines(). The `splitlines()` method splits a string at line boundaries (like 
, 
, or ) and returns a list of substrings, making it a valid method for splitting a string into a list. It is specifically designed for handling multi-line strings.

Answer

join()

Answer

partition()

Question 10

Given s = 'Python', which THREE of the following expressions evaluate to True? (Choose three.)

Accepted Answer

'th' in s. The `in` operator checks for substring membership, and 'th' is indeed a contiguous substring within the string 'Python'. Python's `in` operator performs a linear scan of the string to determine if the substring exists, returning True if found.

Answer

s[0] == 'p'

Answer

s.isupper()

Question 11

A junior developer is writing a script that processes user input. The script reads a line of text from the console and needs to remove any leading or trailing whitespace. The developer uses the strip() method but notices that it also removes other characters like newline. However, the requirement is to remove only spaces (not tabs or newlines). Which course of action should the developer take to remove only leading and trailing spaces?

Accepted Answer

Use strip(' ') with a space argument. The strip() method in Python, when called with no arguments, removes all leading and trailing whitespace characters, including spaces, tabs, and newlines. By passing a space character as the argument, strip(' '), the method is instructed to remove only that specific character (space) from the ends of the string, leaving tabs and newlines intact. This directly meets the requirement to remove only leading and trailing spaces.

Answer

Use replace(' ', '') on the string

Answer

Use lstrip() and rstrip() with no arguments

Answer

Use split() and join()

Question 12

A DevOps engineer is writing a Python script to parse a configuration file. The file contains lines like: 'PARAMETER = value'. The engineer needs to extract the value part after the '=' sign, but there may be multiple equals signs in the value (e.g., 'DATABASE = mysql://user:pass@host/db'). The engineer initially uses line.split('=')[1] but this fails if there are extra equals. Which of the following approaches correctly extracts everything after the first '=' sign?

Accepted Answer

Use line.find('=') and slice from that index+1. Both line.partition('=')[2], line.split('=', 1)[1], and using find() with slicing correctly extract everything after the first '=' sign. The explanation incorrectly dismisses B because it can leave leading whitespace, but C and D also leave any whitespace present. Since the question asks for approaches that correctly extract everything after the first '=', options B, C, and D are all valid.

Answer

Both A and B work

Question 13

A function processes a Unicode string that may contain combining characters (e.g., 'é' as 'e' plus combining acute accent). The function must return the number of visible grapheme clusters (user-perceived characters). Which of the following is the most reliable built-in approach?

Accepted Answer

import unicodedata; len(unicodedata.normalize('NFC', s)). The length of an NFC-normalized string counts Unicode code points after composition, not grapheme clusters. For example, a grapheme like 'a' with combining acute and dot below cannot be fully composed to one code point, so len(NFC) returns 2 or 3, while the user perceives 1 character. Python's standard library does not include a grapheme cluster segmentation algorithm; external libraries like 'regex' (with \X) or 'grapheme' are needed.

Answer

len(s)

Answer

sum(1 for c in s if not unicodedata.combining(c))

Answer

len(s.encode('utf-8'))

Question 14

Which TWO of the following string methods return a boolean value?

Accepted Answer

startswith(). The `startswith()` method returns `True` if the string starts with the specified prefix, otherwise `False`. Similarly, `isalpha()` returns `True` if all characters in the string are alphabetic and there is at least one character, otherwise `False`. Both methods explicitly return a boolean value (`True` or `False`), making them correct choices.

Answer

capitalize()

Answer

format()

Answer

swapcase()

Question 15

In a performance-critical application, you need to concatenate many strings in a loop. Which TWO approaches are most efficient?

Accepted Answer

Using the join() method on a list. The `join()` method on a list (Option B) is efficient because it allocates memory once for the final concatenated string, avoiding repeated reallocation and copying that occurs with immutable strings. `StringIO` (Option E) provides a mutable buffer that accumulates string fragments efficiently, making it suitable for high-performance concatenation in loops.

Answer

Using the % formatting operator

Answer

Using the += operator

Answer

Using the + operator