PCAP Strings Practice Test 3 — 15 Questions

Question 1

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 2

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 3

Which of the following expressions raises a ValueError?

Accepted Answer

'abc'.index('d'). Calling `'abc'.index('d')` raises a `ValueError` when the substring is not found. The `str.index()` method in Python is designed to raise this exception for missing substrings, unlike `str.find()` and `str.rfind()`, which return -1.

Answer

'abc'.index('a')

Answer

'abc'.find('d')

Answer

'abc'.rfind('d')

Question 4

Given the string 'Python', what is the result of 'Python'[::-1]?

Accepted Answer

'nohtyP'. The slice notation [::-1] creates a reversed copy of the string by using a step of -1, which traverses the sequence from the end to the beginning. Since strings in Python are immutable sequences of Unicode characters, this operation returns a new string with the characters in reverse order, preserving the original case of each character.

Answer

'nohtyp'

Answer

'NOHYP'

Answer

'Python'

Question 5

Which TWO of the following are valid string methods in Python?

Accepted Answer

capitalize(). `capitalize()` is a built-in string method in Python that returns a copy of the string with its first character capitalized and the rest lowercased. It is part of the standard string methods available for all string objects in Python.

Answer

rotate()

Answer

shuffle()

Answer

reverse()

Question 6

Which THREE of the following are true about Python strings?

Accepted Answer

They support slicing.. Python strings are sequences, and the slicing syntax (e.g., s[start:stop:step]) allows extracting substrings by specifying indices. This works because strings implement the sequence protocol, including __getitem__ with slice objects.

Answer

They are stored as arrays of ASCII characters.

Answer

They are mutable.

Question 7

Consider the following code: print(type('apple,banana,cherry'.split(','))) What type of value is printed?

Accepted Answer

list. The `split()` method of a string returns a list of substrings. Thus, `type()` on that result returns `<class 'list'>`, indicating that the value is a list.

Answer

tuple

Answer

string

Answer

dict

Question 8

A developer needs to extract the domain name (e.g., 'example.com') from an email address stored in the variable 'email'. The code currently uses `email.split('@')[1]`, which returns the domain part. However, it fails for addresses containing an '@' character in the local part (e.g., 'user@name@domain.com'). Which approach correctly extracts the domain assuming the email is valid?

Accepted Answer

email.rsplit('@', 1)[1]. `rsplit('@', 1)` splits the string from the right, limiting the split to one occurrence, so it always returns the last part after the final '@' character. This correctly extracts the domain even when the local part contains an '@', as in 'user@name@domain.com', where the domain is 'domain.com'.

Answer

email.partition('@')[0]

Answer

email.split('@')[1]

Answer

email.split('@', 1)[1]

Question 9

A developer wants to replace all vowels in a string with their corresponding uppercase letters. They wrote: `s = 'hello world'`; `vowels = 'aeiou'`; `trans = str.maketrans(vowels, vowels.upper())`; `result = s.translate(trans)`. What is the value of `result`?

Accepted Answer

'hEllO wOrld'. The `str.maketrans(vowels, vowels.upper())` creates a translation table mapping each lowercase vowel to its uppercase equivalent. The `translate()` method then replaces only the vowels in the original string, leaving all other characters unchanged. In 'hello world', the vowels 'e', 'o', 'o' become 'E', 'O', 'O', resulting in 'hEllO wOrld' — note that the first 'h' and 'w' remain lowercase because they are consonants.

Answer

'HEllO WOrld'

Answer

'H@ll@ W@rld'

Answer

'hello world'

Question 10

A programmer wants to check whether a string `s` is a palindrome (reads the same forwards and backwards, ignoring case and non-alphanumeric characters). Which code snippet correctly implements this?

Accepted Answer

clean = ''.join(c for c in s if c.isalnum()); return clean.lower() == clean.lower()[::-1]. It first filters out non-alphanumeric characters using `c.isalnum()`, then converts the cleaned string to lowercase before comparing it with its reverse via slicing `[::-1]`. This ensures that case differences and punctuation/spaces are ignored, which is required for a proper palindrome check per the problem statement.

Answer

s.lower() == s.lower()[::-1]

Answer

s == s[::-1]

Answer

return s.lower() == ''.join(reversed(s.lower()))

Question 11

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?

Accepted Answer

Wrap 42 in str(): `print("{0:s}".format(str(42)))`. Both changing the format specifier to 'd' and wrapping the argument in str() resolve the ValueError. The explanation only justifies D and incorrectly implies D is the only correct fix.

Answer

Change `{0:s}` to `{0:str}` to explicitly specify string conversion.

Answer

Change `{0:s}` to `{0:i}` to indicate integer.

Question 12

A script reads a binary file and decodes it as UTF-8. Some bytes are invalid UTF-8 sequences, causing a `UnicodeDecodeError`. The developer wants to replace invalid bytes with the replacement character U+FFFD. Which approach achieves this?

Accepted Answer

data.decode('utf-8', errors='replace'). The `errors='replace'` parameter in Python's `decode()` method replaces any bytes that cannot be decoded as valid UTF-8 with the Unicode replacement character U+FFFD, which is exactly what the developer wants. This approach ensures the script continues processing without raising a `UnicodeDecodeError` while preserving the overall structure of the data.

Answer

data.decode('utf-8', errors='strict')

Answer

data.decode('utf-8', errors='surrogateescape')

Answer

data.decode('utf-8', errors='ignore')

Question 13

What is the output of `print('-'.join(['a', 'b', 'c']))`?

Accepted Answer

a-b-c. The `join()` method in Python concatenates the elements of an iterable (here, a list of strings) into a single string, using the string on which it is called as the separator. In this case, `'-'.join(['a', 'b', 'c'])` inserts a hyphen between each element, producing the string `'a-b-c'`. The `print()` function then outputs that string without quotes.

Answer

['a', '-', 'b', '-', 'c']

Answer

('a', '-', 'b', '-', 'c')

Answer

a,b,c

Question 14

Given `s = 'Python'`, what is the result of `s[-4::-1]`?

Accepted Answer

'tyP'. The slice `s[-4::-1]` starts at index -4 (which corresponds to the character 't' in 'Python') and proceeds backward to the beginning of the string because the step is -1. This extracts 't', 'y', 'P', resulting in 'tyP'. Option D is correct because it matches this exact backward traversal from index -4 to the start.

Answer

'ty'

Answer

'tho'

Answer

'nohtyP'

Question 15

Which TWO of the following string methods return a new string with all characters converted to lowercase? (Select exactly two.)

Accepted Answer

str.lower(). Str.lower(), is correct because it returns a new string with all Unicode characters converted to lowercase according to the current locale's case mapping. Option E, str.casefold(), is correct because it returns a string suitable for case-insensitive comparisons by applying aggressive folding that handles special cases like the German 'ß' (which becomes 'ss'), going beyond simple lowercase conversion.

Answer

str.title()

Answer

str.swapcase()

Answer

str.capitalize()