PCAP Strings Practice Test 6 — 15 Questions

Question 1

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 2

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 3

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 4

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 5

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]

Question 6

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 7

Refer to the exhibit. Which of the following fixes the error?

Accepted Answer

Both A and B. Both A and B produce the string 'Hello5' without error. In Python, the + operator concatenates strings, so 'Hello' + '5' works. Option B converts the integer 5 to a string using str() before concatenation, which also works. Option D uses the * operator to repeat the string 'Hello' five times, producing 'HelloHelloHelloHelloHello', which is a valid operation but does not fix the error described in the exhibit (likely a TypeError from trying to concatenate a string and an integer).

Answer

print('Hello' + '5')

Answer

print('Hello' + str(5))

Answer

print('Hello' * 5)

Question 8

Which of the following is the BEST practice for building a large string by concatenating many smaller strings in Python?

Accepted Answer

result = ''.join(parts). `''.join(parts)` is the most efficient way to concatenate a large number of strings in Python. It allocates memory once for the final string by iterating over the list and copying each part into the result buffer, avoiding the O(n²) time complexity of repeated concatenation in a loop.

Answer

result = sum(parts, '')

Answer

result = str.concat(*parts)

Answer

result = ''; for part in parts: result += part

Question 9

A team is using f-strings to format a report. They have a variable `value = 0.123456789` and want to display it with exactly 3 significant digits. They write `f"{value:.3g}"`. The output is '0.123'. They expected '0.123'. Is the output correct? If not, what change would produce '0.123'?

Accepted Answer

The output is correct as is.. The format specifier `.3g` in an f-string instructs Python to format the number with 3 significant digits using general format. For `0.123456789`, the first three significant digits are '123', and the general format automatically switches to fixed-point notation when the exponent is small, producing '0.123' exactly as expected.

Answer

Use `f"{value:.3s}"`

Answer

Use `f"{value:.3f}"`

Answer

Use `f"{value:.3e}"`

Question 10

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 11

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 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

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()

Question 15

Which THREE of the following escape sequences are valid in a Python string and represent a single character? (Select exactly three.)

Accepted Answer

\'. The backslash followed by a single quote (\') is a valid escape sequence in Python that represents a literal single quote character, allowing it to appear inside a single-quoted string without terminating the string. This sequence is interpreted as a single character by the Python parser.

Answer

\x

Answer

\q