PCAP Strings Practice Test 9 — 15 Questions

Question 1

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}'. Option C (f-string) is the most Pythonic and recommended for new code per PEP 498. Option A (% formatting) is older. Option B (.format()) is also fine but f-strings are often preferred for readability when variables are available. Option D (concatenation) is prone to errors and less readable.

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 2

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.. Option B (strings are immutable) and Option D (concatenation creates a new string) are correct. Option A is wrong because strings are immutable, not mutable. Option C is wrong because .append() is not a method of strings; it belongs to lists. Option E is wrong because item assignment is not allowed on strings (immutable).

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 3

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. Option B uses slicing with default step -1 to reverse the string and compares. Option A uses reversed() which returns an iterator, so comparison to a string fails. Option C uses .reverse() which is a list method. Option D uses slicing but with step 1, which does not reverse.

Answer

reversed(s) == s

Answer

s[::1] == s

Answer

s.reverse() == s

Question 4

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

Accepted Answer

'Python'. Option D is correct because 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 5

What will the above code output?

Accepted Answer

Index out of range. Option B is correct because accessing index 100 on a string of length 11 raises an IndexError, which is caught and the message is printed. Option A would happen if the error were not caught. Option C is not thrown. Option D is false because the error is caught and the except block runs.

Answer

The program runs without output.

Answer

The program crashes with an unhandled IndexError.

Answer

ValueError is raised.

Question 6

What is the output of the code in the exhibit?

Accepted Answer

Alice is 30 years old.. Option A is correct because the f-string substitutes the variables name and age. Option B has incorrect formatting with curly braces. Option C places age before name. Option D uses incorrect variable names.

Answer

{name} is {age} years old.

Answer

Alice is 30 years old.

Answer

30 is Alice years old.

Question 7

Given the code above, what is printed? Note: each backslash is a single character.

Accepted Answer

23. Option D is correct. The raw string r"..." treats backslashes as literal characters. The path has: C, :, \, U, s, e, r, s, \, J, o, h, n, \, D, o, c, u, m, e, n, t, s. That's 23 characters. Option A counts standard string escape sequences (e.g., \U would be interpreted as Unicode if not raw). Option B and C are other miscalculations.

Answer

21

Answer

22

Answer

24

Question 8

Which THREE of the following string methods return a boolean value (True or False)? (Choose exactly 3 correct answers.)

Accepted Answer

isspace(). Options A (isalpha()), B (isdigit()), and C (isspace()) all return boolean. Option D (find()) returns an integer index or -1. Option E (replace()) returns a string.

Answer

replace()

Answer

find()

Question 9

A developer writes: print('{:,}'.format(1234567)). What is the output?

Accepted Answer

1,234,567. Option B is correct. The format specifier ',,' is a thousands separator (comma) in the locale-agnostic sense for the US locale, producing commas every three digits. Option A has no commas. Option C uses periods. Option D uses spaces.

Answer

1234567

Answer

1.234.567

Answer

1 234 567

Question 10

A developer uses the .index() method on a string to find the position of a substring. If the substring is not found, what exception is raised?

Accepted Answer

ValueError. Option B is correct; .index() raises ValueError when the substring is not found. Option A (IndexError) is for out-of-range indexing. Option C (KeyError) is for dictionary keys. Option D (TypeError) is for type mismatches.

Answer

KeyError

Answer

IndexError

Answer

TypeError

Question 11

A developer wants to create a string that contains the current year and month in the format 'YYYY-MM'. The year and month are stored in integer variables year and month. Which expression would produce the desired result?

Accepted Answer

f"{year}-{month:02d}". Option A uses an f-string with zero-padding for month, ensuring two digits. Option B concatenation omits zero-padding. Option C uses old-style formatting without zero-pad. Option D raises TypeError due to int+str.

Answer

year + '-' + month

Answer

str(year) + '-' + str(month)

Answer

'%s-%s' % (year, month)

Question 12

A log processing script receives a multiline string log. The script needs to check if the string ends with the substring 'ERROR'. Which method should be used?

Accepted Answer

log.endswith('ERROR'). Option B (endswith) is the correct method to check the end of a string. Option A finds anywhere. Option C is overly complex. Option D checks anywhere.

Answer

log.find('ERROR') != -1

Answer

log.rfind('ERROR') == len(log)-5

Answer

'ERROR' in log

Question 13

A programmer needs to replace every occurrence of 'cat' with 'dog' in a string s, but only if 'cat' is not preceded by 'big'. Which regex substitution would achieve this?

Accepted Answer

re.sub(r'(?<!big)cat', 'dog', s). Option C uses negative lookbehind to exclude 'bigcat' from replacement. Option A replaces all 'cat'. Option B replaces 'bigcat'. Option D replaces only 'cat' preceded by 'big'.

Answer

re.sub(r'bigcat', 'dog', s)

Answer

re.sub(r'cat', 'dog', s)

Answer

re.sub(r'(?<=big)cat', 'dog', s)

Question 14

What is the result of the expression 'Hello'[1:3]?

Accepted Answer

'el'. In Python, string slicing uses the syntax `string[start:stop]`, where `start` is inclusive and `stop` is exclusive. For `'Hello'[1:3]`, the indices are: index 1 = 'e', index 2 = 'l', and index 3 is not included, so the slice returns 'el'. This is a fundamental string slicing behavior defined in Python's sequence protocol.

Answer

'lo'

Answer

'He'

Answer

'ell'

Question 15

Which method returns the lowest index where a specified substring is found, or -1 if not found?

Accepted Answer

find(). Option A (find) returns -1 if not found. Option B (index) raises ValueError. Option C (search) is from re module. Option D (locate) is not a Python method.

Answer

locate()

Answer

search()

Answer

index()