PCAP Strings Practice Test 4 — 15 Questions

Question 1

Which TWO of the following expressions evaluate to `True`? (Select exactly two.)

Accepted Answer

'ab' in 'abc'. The `in` operator checks if the substring 'ab' appears anywhere within the string 'abc'. Since 'abc' contains the consecutive characters 'a' followed by 'b', the expression evaluates to True.

Answer

'x' in 'abc'

Answer

'ab' not in 'abc'

Answer

'abc' in 'ab'

Question 2

Consider the following code:

name = "Alice"
age = 30
print(f"{name} is {age} years old.")

What is the output of the above code?

Accepted Answer

Alice is 30 years old.. Given the code:

name = "Alice"
age = 30
print(f"{name} is {age} years old.")

The f-string correctly interpolates the variables, producing 'Alice is 30 years old.' Option D is correct. Option A incorrectly includes an extra comma after 30. Option B uses the literal string 'Name' instead of the variable name. Option C adds an extra period at the end.

Answer

Alice is 30, years old.

Answer

Name is 30 years old.

Answer

Alice is 30 years old..

Question 3

What is the cause of the error?

Accepted Answer

The result of `username.encode('utf-8')` is bytes, and Python does not allow concatenating str with bytes.. `username.encode('utf-8')` returns a bytes object, and Python's `+` operator does not allow concatenation of `str` and `bytes` types. This raises a `TypeError: can only concatenate str (not "bytes") to str` because the other operand in the concatenation is a string literal.

Answer

The error is because `encode` returns a string, but the plus operator expects two strings.

Answer

The `username` variable is of type bytes, so encoding is unnecessary.

Answer

The encode method is called incorrectly; it should be `username.encode()` without argument.

Question 4

A developer needs to check if a filename starts with the prefix 'report_'. Which string method should be used?

Accepted Answer

startswith(). The `startswith()` method is the correct string method in Python to check if a string begins with a specified prefix. It returns `True` if the string starts with the given substring, otherwise `False`, making it the exact tool for checking if a filename starts with 'report_'.

Answer

prefix()

Answer

starts()

Answer

beginwith()

Question 5

What is the output of 'hello'.count('l')?

Accepted Answer

2. The string method `count('l')` returns the number of non-overlapping occurrences of the substring `'l'` in the string `'hello'`. The string `'hello'` contains the character `'l'` at indices 2 and 3, so the count is 2. Therefore, option D is correct.

Answer

1

Answer

3

Answer

0

Question 6

What is the result of 'PyThon'.lower()?

Accepted Answer

'python'. The `.lower()` method in Python returns a new string with all alphabetic characters converted to lowercase. Since the original string 'PyThon' contains uppercase 'P' and 'T', applying `.lower()` yields 'python'. Option B is correct because it is the only option that shows all characters in lowercase.

Answer

'Python'

Answer

'PYTHON'

Answer

'pYTHON'

Question 7

Given s = 'Python', what is s[1:4]?

Accepted Answer

'yth'. In Python, string slicing with `s[start:stop]` extracts characters from index `start` up to but not including index `stop`. Since indexing starts at 0, `s[1:4]` on 'Python' takes indices 1 ('y'), 2 ('t'), and 3 ('h'), resulting in 'yth'. Option B is correct because it exactly matches this slice.

Answer

'pyt'

Answer

'ytho'

Answer

'Pyt'

Question 8

A web application receives a byte string b'\xc3\xa9' which represents the character 'é' in UTF-8. The developer wants to convert it to a Python string. Which operation should be used?

Accepted Answer

b'\xc3\xa9'.decode('utf-8'). The byte string b'\xc3\xa9' is a UTF-8 encoded representation of the character 'é'. To convert it to a Python string, you must decode it using the .decode('utf-8') method, which interprets the bytes according to the UTF-8 encoding and returns a Unicode string.

Answer

b'\xc3\xa9'.encode('utf-8')

Answer

b'\xc3\xa9'.tostring()

Answer

str(b'\xc3\xa9', 'ascii')

Question 9

A developer is building a large string by concatenating many substrings in a loop using '+'. What is the main performance issue?

Accepted Answer

Each concatenation creates a new string object, leading to quadratic time complexity. In Python, strings are immutable, so the '+' operator does not modify an existing string but creates a new string object each time it is used. In a loop, this results in O(n²) time complexity because each concatenation copies the entire accumulated string, making it highly inefficient for large or many substrings.

Answer

String concatenation is not allowed in loops

Answer

Strings are immutable, so concatenation is impossible

Answer

The '+' operator works only for characters, not strings

Question 10

Which TWO of the following string methods return a new string without modifying the original?

Accepted Answer

replace(). The `replace()` method returns a new string with all occurrences of a substring replaced by another substring, without altering the original string. Similarly, `strip()` returns a new string with leading and trailing whitespace (or specified characters) removed, leaving the original unchanged. Both methods are non-mutating because strings in Python are immutable.

Answer

index()

Answer

find()

Answer

count()

Question 11

Which THREE of the following are valid escape sequences in Python strings?

Accepted Answer

. 	 is the standard escape sequence for a horizontal tab character in Python strings. Escape sequences in Python begin with a backslash followed by a specific character, and 	 is defined in the Python language specification (similar to C) to represent the ASCII tab character (0x09).

Answer

\g

Answer

\h

Question 12

Refer to the exhibit. What is the output?

Accepted Answer

18. The code prints the length of the string 'Python programming', which includes the space between 'Python' and 'programming', resulting in 18 characters. Therefore, the output is 18.

Answer

20

Answer

17

Answer

19

Question 13

What is the likely outcome of running the following code?

```python
with open("C:\Users\path\file.txt", "r") as f:
    print(f.read())
```

Accepted Answer

The program raises a SyntaxError due to invalid escape sequences.. The code likely contains backslash sequences (e.g., `\U`, `\p`, or other non-standard escapes) that are not valid escape sequences in Python. Starting with Python 3.12, such invalid sequences raise a `SyntaxError` at compile time, preventing the program from running. In earlier versions, a `DeprecationWarning` is issued, but the code may run. The error is not about file operations or path resolution; it's a compile-time syntax error. To avoid this, use raw strings (`r"..."`) or double backslashes (`\`).

Answer

The program runs but the file contents are incorrect.

Answer

The program raises a FileNotFoundError because the path is invalid after escape interpretation.

Answer

The file is opened successfully because backslashes are ignored.

Question 14

A developer wrote a script that processes user input. The script expects a string containing a list of comma-separated values. The user enters "apple, banana, cherry, date". The script uses split() to separate the items. Which code correctly extracts the second item without leading/trailing spaces?

Accepted Answer

items = data.split(", "); second = items[1]. Both B and C correctly extract the second item without leading/trailing spaces. B splits on ', ' to get ['apple', 'banana', 'cherry', 'date'] and accesses index 1. C splits on ',' to get ['apple', ' banana', ' cherry', ' date'], then applies .strip() to items[1], yielding 'banana'. Since the question asks for correct extraction without specifying a preferred method, C is also correct.

Answer

items = data.split(); second = items[1]

Answer

items = data.split(","); second = items[2].strip()

Question 15

In a data processing pipeline, a string variable 'text' contains the value "Hello
World
". The developer needs to count the number of lines in the text. Which expression returns the correct line count (treating 
 and 
 as line terminators)?

Accepted Answer

text.count('
'). For text = "Hello
World
", text.count('
') equals 2 and len(text.splitlines()) equals 2. Since the question asks which expression returns the correct line count for the given value, both A and B are correct. The question needs revision to have a unique answer, e.g., by using a string that does not end with a newline.

Answer

text.count('
') + text.count('
')

Answer

len(text.split('
'))