PCAP Strings Practice Test 9 — 15 Questions

Question 1

A developer tries to modify a string: s = 'hello'; s[0] = 'H'. What happens when this code runs?

Accepted Answer

It raises a TypeError: 'str' object does not support item assignment. Strings in Python are immutable, meaning their contents cannot be changed after creation. Attempting to assign a new character to an index position (e.g., s[0] = 'H') raises a TypeError: 'str' object does not support item assignment. To modify a string, you must create a new string using slicing or concatenation.

Answer

It changes the string to 'Hello'

Answer

It creates a new string 'Hello' and assigns it to s

Answer

It raises an IndexError because index 0 is out of range

Question 2

A developer wants to check if a string 'example.txt' ends with '.txt'. Which expression returns True?

Accepted Answer

'example.txt'.endswith('.txt'). The `endswith()` method is specifically designed to check if a string ends with a given suffix. In this case, `'example.txt'.endswith('.txt')` returns `True` because the string ends with the substring '.txt'.

Answer

'example.txt'.startswith('.txt')

Answer

'example.txt'.find('.txt')

Answer

'example.txt'.rsplit('.',1)

Question 3

A developer needs to format a floating-point number 123.456789 with exactly 2 decimal places and a width of 10 characters, right-aligned. Which format specifier accomplishes this?

Accepted Answer

:10.2f. The format specifier `:10.2f` combines a total width of 10 characters with exactly 2 decimal places for a floating-point number, right-aligned by default. The `f` type ensures fixed-point notation, and the width of 10 includes the decimal point and digits, padding with spaces on the left.

Answer

:.2f

Answer

:10.2g

Answer

:10.2e

Question 4

Which TWO of the following string methods return a boolean value (True or False)?

Accepted Answer

str.startswith(). Both `str.startswith()` and `str.isdigit()` return a boolean value (`True` or `False`) because they are designed for conditional checks. `str.startswith()` checks if the string starts with a given prefix, while `str.isdigit()` checks if all characters in the string are digits. In contrast, `str.upper()` returns a new string, `str.split()` returns a list, and `str.find()` returns an integer index. Therefore, options C and D are the correct answers.

Answer

str.upper()

Answer

str.split()

Answer

str.find()

Question 5

Which THREE of the following are valid ways to create a string in Python?

Accepted Answer

'Hello'. In Python, valid string literals can be enclosed in single quotes, double quotes, triple single quotes, or triple double quotes. Formatted string literals (f-strings) are also valid. Option A is invalid because it uses mismatched quote characters: it opens with a single quote but closes with a double quote. Option B uses consistent single quotes. Option C is an f-string. Option D uses backticks, which are not valid Python string delimiters. Option E uses triple single quotes, which are valid for multi-line strings.

Answer

'Hello"

Answer

`Hello`

Question 6

Which TWO of the following operations can be performed on a string?

Accepted Answer

Slicing with [::]. String slicing with the syntax `[start:stop:step]` (e.g., `[::]`) is a built-in operation for strings in Python, allowing extraction of substrings. Option E is correct because the `+` operator performs string concatenation, creating a new string by joining two strings together.

Answer

Extend with .extend()

Answer

Append with .append()

Answer

Pop with .pop()

Question 7

Consider the following code snippet: s = 'abcdefgh'; result = s[7:3:-2]; print(result). What is the output?

Accepted Answer

hf. The slice s[7:3:-2] starts at index 7 (character 'h'), goes backwards with step -2, and stops before index 3. The indices visited are 7 and 5, yielding 'h' and 'f', so the result is 'hf'. Option B is correct because the step is negative, meaning the slice moves from right to left, and the stop index is exclusive.

Answer

fh

Answer

h

Answer

hfd

Question 8

Which TWO of the following can be used to remove leading whitespace (spaces, tabs, newlines) from a string? (Choose exactly 2 correct answers.)

Accepted Answer

lstrip(). The `lstrip()` method removes all leading whitespace characters (spaces, tabs, newlines) from the left side of a string. `strip()` removes leading and trailing whitespace, so it also satisfies the requirement of removing leading whitespace. Both are built-in string methods in Python.

Answer

rstrip()

Answer

trim()

Answer

clean()

Question 9

A developer wants to convert a string 'Python' to all uppercase letters. Which string method should be used?

Accepted Answer

upper(). The `upper()` method returns a copy of the string with all lowercase characters converted to uppercase. Since the goal is to convert 'Python' to 'PYTHON', `upper()` is the correct and most direct method for this task.

Answer

capitalize()

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title()

Answer

swapcase()

Question 10

A developer is working on a logging system where dynamic values are inserted into a template string. The template is 'User %s logged in at %s'. The developer has the username and timestamp as separate variables. Which approach is most Pythonic (PEP 498) and recommended for new code?

Accepted Answer

Use an f-string: f'User {username} logged in at {timestamp}'. PEP 498 introduced f-strings (formatted string literals) as the recommended approach for string formatting in Python 3.6+. They are concise, readable, and evaluated at runtime, allowing direct embedding of expressions. This aligns with the 'Pythonic' principle of simplicity and is the preferred style for new code according to the official Python documentation.

Answer

Use %-formatting: 'User %s logged in at %s' % (username, timestamp)

Answer

Use .format(): 'User {} logged in at {}'.format(username, timestamp)

Answer

Concatenate: 'User ' + username + ' logged in at ' + timestamp

Question 11

Which TWO statements about Python strings are correct? (Choose exactly 2 correct answers.)

Accepted Answer

Strings are immutable; operations like concatenation produce a new string.. Python strings are immutable, meaning once a string object is created, its content cannot be changed. Any operation that appears to modify a string, such as concatenation with the + operator, actually creates a brand-new string object in memory, leaving the original unchanged.

Answer

Strings are mutable; you can change individual characters via indexing.

Answer

Strings have an .append() method to add characters at the end.

Answer

You can assign a new character to a position in a string using indexing: s[0] = 'a'.

Question 12

A developer wants to check if a string 'racecar' is a palindrome by comparing it to its reverse. Which code completes the task correctly?

Accepted Answer

s[::-1] == s. The slicing syntax `s[::-1]` creates a reversed copy of the string `s`, and comparing it to `s` with `==` checks if the string reads the same forwards and backwards, which is the definition of a palindrome. For the string 'racecar', `s[::-1]` returns 'racecar', so the comparison is `True`.

Answer

reversed(s) == s

Answer

s[::1] == s

Answer

s.reverse() == s

Question 13

Given the code: s = 'Python'; t = s; s = s + '3.0'. What is the value of t after these lines execute?

Accepted Answer

'Python'. Strings in Python are immutable. The assignment `t = s` makes `t` reference the same string object as `s`. When `s = s + '3.0'` executes, a new string object `'Python3.0'` is created and bound to `s`, while `t` still references the original string `'Python'`. Thus, `t` remains `'Python'`.

Answer

It raises an error because s was reassigned.

Answer

''

Answer

'Python3.0'

Question 14

What will the above code output?

Accepted Answer

Index out of range. The code attempts to access an index that is outside the valid range of the string. In Python, strings are zero-indexed, so for a string of length n, valid indices are 0 to n-1. Accessing an index equal to or greater than the length raises an IndexError, which is exactly what 'Index out of range' describes.

Answer

The program runs without output.

Answer

The program crashes with an unhandled IndexError.

Answer

ValueError is raised.

Question 15

What is the output of the code in the exhibit?

Accepted Answer

Alice is 30 years old.. The code uses an f-string which substitutes the values of the variables `name` and `age` into the string. Evaluating the expression results in 'Alice is 30 years old.', matching option B. Option A shows the literal braces, option C displays the variable names instead of their values, and option D reverses the order of the variables.

Answer

{name} is {age} years old.

Answer

name is age years old.

Answer

30 is Alice years old.