PCPP1 Library Modules — 25 Questions

Question 1

When parsing an XML document using xml.etree.ElementTree, you want to find all 'item' tags that are immediate children of the root element. Which method is most efficient for this?

Accepted Answer

root.findall('item'). The findall() method with a direct path is the standard way to retrieve specific children.

Answer

root.iter('item')

Answer

root.find('item')

Answer

root.get('item')

Question 2

You are writing data to a CSV file using csv.writer. You want to ensure that row delimiters are handled correctly across different operating systems. What should you set the 'lineterminator' parameter to?

Accepted Answer

lineterminator='
'. The lineterminator parameter should be explicitly set to '
' for cross-platform compatibility.

Answer

lineterminator='
'

Answer

lineterminator=os.linesep

Answer

lineterminator='\r'

Question 3

Which class in xml.etree.ElementTree should you use to parse an XML file from a file object?

Accepted Answer

ElementTree.parse(). The parse() function is the standard way to read XML from a file object.

Answer

ElementTree.XML()

Answer

ElementTree.load()

Answer

ElementTree.read()

Question 4

What is the result of using '?' as a placeholder in sqlite3 for a parameter that is a Python list?

Accepted Answer

It raises a ProgrammingError.. sqlite3 does not automatically expand lists; you must use a tuple of values or construct the SQL dynamically.

Answer

It automatically converts the list to a comma-separated string.

Answer

It works as expected.

Answer

It only takes the first element of the list.

Question 5

In xml.etree.ElementTree, what is the difference between find() and findall() when used with XPath support?

Accepted Answer

findall() returns a list, find() returns a single element.. findall() supports full XPath syntax, whereas find() supports a more limited subset.

Answer

find() is faster for large trees.

Answer

findall() requires an iterator.

Answer

findall() is recursive, find() is not.

Question 6

Which logging configuration would effectively suppress all log messages?

Accepted Answer

logging.disable(logging.CRITICAL + 1). Setting the level to logging.CRITICAL + 1 (or any value higher than the highest defined level) suppresses all logs.

Answer

logging.basicConfig(level=0)

Answer

logging.disable(logging.CRITICAL)

Answer

logging.getLogger().setLevel(logging.NOTSET)

Question 7

You want to retrieve a list of all section names from a ConfigParser object. How do you do this?

Accepted Answer

parser.sections(). The sections() method returns a list containing all section names except the DEFAULT section.

Answer

list(parser.sections())

Answer

parser.keys()

Answer

parser.get_sections()

Question 8

Which TWO of the following are true about the logging module?

Accepted Answer

Loggers are organized in a hierarchy.. Option C is correct because Python's logging module arranges loggers in a dotted-name hierarchy rooted at the root logger, so a logger named 'a.b' is a child of 'a', and messages propagate up to ancestor loggers' handlers unless propagation is disabled. Option E is correct because the logging module is explicitly designed to be thread-safe: its module-level functions and the Logger, Handler, and Filter classes use locks (e.g., Handler.acquire/release around emit) so multiple threads can log concurrently without corrupting output. Option A is wrong because logging levels are integer constants (DEBUG=10, INFO=20, WARNING=30, ERROR=40, CRITICAL=50), not strings, although string names can be converted via logging.getLevelName or setLevel. Option B is wrong because a single logger can have any number of handlers attached via addHandler(), which is the standard way to send output to both a file and the console. Option D is wrong because logging is not inherently synchronous in the sense implied; handlers may use QueueHandler/QueueListener or emit asynchronously, and the default behavior is simply that emit is called inline, but the module does not guarantee synchronous-only operation.

Answer

Logging levels are strings.

Answer

You cannot have multiple handlers for a single logger.

Answer

Logging is synchronous by default.

Question 9

Which TWO of the following are valid ways to read sections in a configparser object?

Accepted Answer

for section in parser.sections():. Option D, `for section in parser.sections():`, is correct because `ConfigParser.sections()` returns a list of the section names (excluding DEFAULT) in the configuration, which is the canonical way to iterate over sections. Option E, `for section in parser:`, is also correct because ConfigParser implements the mapping/iterable protocol, so iterating the parser object directly yields section names just like iterating a dictionary yields its keys. Option A is wrong because there is no `get_all()` method on ConfigParser; the closest is `items()` or `_sections`. Option B is wrong because `parser.keys()` is not a standard ConfigParser method (it exists on the underlying mapping in some versions but is not the documented API for reading sections). Option C is wrong because `parser.read()` is used to read filenames into the parser and returns a list of successfully parsed filenames, not section names.

Answer

for section in parser.get_all():

Answer

for section in parser.keys():

Answer

for section in parser.read():

Question 10

Which THREE of the following are valid states/modes for the csv.QUOTE_* constants?

Accepted Answer

csv.QUOTE_NONE. The Python csv module defines exactly three quoting constants that control how the writer quotes fields: csv.QUOTE_MINIMAL (option E), csv.QUOTE_ALL (option B), and csv.QUOTE_NONE (option A). csv.QUOTE_MINIMAL is the default mode and quotes only fields that contain the delimiter, quotechar, or any character in lineterminator. csv.QUOTE_ALL quotes every field regardless of content, and csv.QUOTE_NONE disables quoting entirely, requiring an escapechar to handle embedded delimiters or quote characters. Options C (csv.QUOTE_EVERYTHING) and D (csv.QUOTE_AUTO) are not defined in the csv module and would raise an AttributeError if referenced, so they are not valid quoting modes.

Answer

csv.QUOTE_EVERYTHING

Answer

csv.QUOTE_AUTO

Question 11

Which THREE of the following are components of the logging module?

Accepted Answer

Formatter. In Python's logging module, the Logger (option C) is the entry point that exposes methods like debug(), info(), and warning() and routes records into the logging hierarchy. The Handler (option E) is the component that actually dispatches each LogRecord to a destination such as a StreamHandler (console), FileHandler, or SysLogHandler, applying levels and optional filters. The Formatter (option A) defines the layout of the emitted text via format strings (e.g., '%(asctime)s - %(name)s - %(levelname)s - %(message)s'), converting a LogRecord into the final string written by a handler. The remaining options, Dispatcher (B) and Manager (D), are not part of the logging module's public component model; the closest internal element is the logging.Manager, which merely tracks loggers and their hierarchy and is not one of the four documented components (Logger, Handler, Formatter, Filter).

Answer

Dispatcher

Answer

Manager

Question 12

Which THREE of the following are valid parsing modes for the XML module?

Accepted Answer

xml.etree.ElementTree.XMLParser(). XML can be parsed via strings, files, or incremental/streamed methods.

Answer

xml.etree.ElementTree.read()

Answer

xml.etree.ElementTree.load_xml()

Question 13

Which THREE of the following are valid logging levels?

Accepted Answer

DEBUG. DEBUG (A), WARNING (B), and INFO (E) are all valid logging levels, as defined in standard logging frameworks such as Python's logging module and syslog severity levels. DEBUG is the lowest severity, used for detailed diagnostic information; INFO is used for general operational messages; and WARNING indicates a potential issue that does not prevent normal operation. NOTICE (C) is a valid syslog severity level but is not part of the standard logging levels in most application logging frameworks, and FATAL (D) is not a standard logging level in Python's logging module (CRITICAL is used instead). Therefore, only A, B, and E are correct.

Answer

NOTICE

Answer

FATAL

Question 14

You are writing a Python script that must parse a large XML file using xml.etree.ElementTree. The file contains many namespaces, and you need to find all elements with the local name 'price' regardless of their namespace. Which approach is most efficient and correct?

Accepted Answer

Use root.findall('.//{*}price') with a wildcard namespace.. The wildcard namespace syntax '{*}price' in ElementTree's findall matches any namespace, including none. It is the most efficient and correct method for finding elements by local name across namespaces. Other options either limit to a specific namespace, require manual iteration, or alter the document.

Answer

Use root.findall('.//price') after stripping all namespace prefixes from the file.

Answer

Iterate over all elements with root.iter() and check if the tag ends with '}price' or equals 'price'.

Answer

Use root.findall('.//{http://example.com}price') with a specific namespace.

Question 15

You are building a Python tool that must parse a configuration file generated by a legacy application. The file contains sections whose keys are case-sensitive and may include duplicate keys within the same section; the tool must preserve every value and detect duplicates for a warning report. Which approach using configparser is technically correct?

Accepted Answer

Subclass configparser.ConfigParser, override optionxform to preserve case, and override _read to collect duplicates before calling the parent implementation.. The requirement to preserve every value while detecting duplicates cannot be met by standard configparser behavior, because both ConfigParser and RawConfigParser collapse duplicate keys into a single value. Subclassing and overriding optionxform and _read allows interception of raw lines, preserving case and capturing duplicates before the parent parser removes them. This is the only listed approach that satisfies both constraints.

Answer

Use configparser.ConfigParser(strict=False, allow_no_value=True) and inspect parser.items(section) to detect duplicate keys.

Answer

Use configparser.ConfigParser(strict=True) and rely on parser.read() to raise DuplicateOptionError during parsing.

Answer

Use configparser.RawConfigParser and access parser._sections directly to retrieve all duplicate keys and values.

Question 16

You are working with the os module to manipulate file paths in a cross-platform Python application. You need to perform operations that are portable across Windows and Unix-like systems. Which TWO of the following are valid and recommended uses of the os.path submodule for path manipulation? (Choose two.)

Accepted Answer

os.path.join('folder', 'file.txt') to construct a path using the correct separator for the current OS.. os.path.join() and os.path.split() are fundamental for portable path manipulation. join constructs paths using the correct separator, and split separates the directory and filename. These functions abstract away platform differences, making code cross-platform. Other functions like isdir, abspath, and normpath are useful but not the primary recommended uses for path manipulation in the context of the question.

Answer

os.path.abspath('file.txt') to convert a relative path to an absolute path based on the current working directory.

Answer

os.path.normpath('folder//file.txt') to normalize a path by collapsing redundant separators.

Answer

os.path.isdir('C:\Users\file.txt') to check if a path is a directory, regardless of the operating system.

Question 17

You are writing a Python script that needs to parse a JSON string containing a date in ISO 8601 format. You want to automatically convert this date string into a datetime.date object during parsing. Which of the following approaches using the json module is correct?

Accepted Answer

Pass a function to the object_hook parameter of json.loads that checks if the key is 'date' and returns a datetime.date object.. To convert date strings during JSON parsing, you should use the object_hook parameter of json.loads. This parameter allows you to specify a function that is called with each decoded JSON object (dictionary), enabling you to transform values, such as converting a date string to a datetime.date object. The other parameters are for specific types (floats, ints) or for serialization (default).

Answer

Use the parse_float parameter to specify a function that converts date strings to datetime.date objects.

Answer

Use the default parameter of json.loads to provide a function that converts date strings to datetime.date objects.

Answer

Use the parse_int parameter to specify a function that recognizes date strings and converts them.

Question 18

You are writing a Python script to monitor a directory. When a new file appears, you need to read its last line efficiently without loading the entire file into memory. The files can be very large (several gigabytes). Which approach using the os module is most appropriate?

Accepted Answer

Use os.stat() to get the file size, then open the file in binary mode and seek to a position near the end to read the last line.. The correct approach uses os.stat() to get the file size, then opens the file in binary mode and seeks to a position near the end. This avoids reading the entire file, which is crucial for very large files. It leverages the os module's file metadata capabilities while using standard file I/O for efficient reading.

Answer

Use os.path.getsize() to check the file size, then if it is small enough, read the whole file; otherwise, raise an exception.

Answer

Use os.open() with the os.O_RDONLY flag to get a file descriptor, then call os.lseek() to move to the end and os.read() to read backwards until a newline is found.

Answer

Use os.read() to read the entire file content into a bytes object, then split by newline and take the last element.

Question 19

You are using the `os` module to manipulate file paths in a cross-platform script. You need to extract the filename without extension from a path, and also check if a path is absolute. Which TWO of the following statements about the `os.path` module are correct? (Choose two.)

Accepted Answer

`os.path.basename('/home/user/file.txt')` returns `'file.txt'`.. The correct statements are that `os.path.splitext` splits the extension correctly, and `os.path.basename` returns the filename. These are fundamental behaviors of the `os.path` module. The other options contain misconceptions about absolute paths, cross-platform joining, and normalization details.

Answer

`os.path.normpath('home/../user/file.txt')` returns `'user/file.txt'`.

Answer

`os.path.isabs('C:\Users\file.txt')` returns `True` on Windows.

Answer

`os.path.join('home', 'user', 'file.txt')` returns `'home/user/file.txt'` on all platforms.

Question 20

You are designing a class that needs to support the context manager protocol. The class manages a network connection that must be closed exactly once, even if multiple exceptions occur within the with block. Which implementation correctly ensures that the connection is closed and that any exception is propagated?

Accepted Answer

Define __enter__ to return self and __exit__ to close the connection and return False.. The correct implementation defines __enter__ to return self and __exit__ to close the connection and return False. This ensures the connection is closed exactly once when the with block exits, and any exception is propagated because returning False does not suppress it. This adheres to the context manager protocol.

Answer

Define __enter__ to return self and __exit__ to close the connection and return True.

Answer

Define __enter__ to close the connection and return self, and __exit__ to do nothing.

Answer

Define __enter__ to return self and __exit__ to close the connection and re-raise the exception if one occurred.