PCPP1 Library Modules Practice Test 4 — 15 Questions

Question 1

Which THREE of the following are valid parameters for the csv.writer constructor?

Accepted Answer

lineterminator. The csv.writer constructor accepts a dialect and formatting parameters, and lineterminator (A) is a valid parameter that sets the string used to terminate lines written by the writer, defaulting to '
'. quotechar (D) is also valid and specifies the single character used to quote fields containing special characters such as the delimiter or quotechar itself. delimiter (E) is valid as well, defining the one-character string used to separate fields, defaulting to a comma. The encoding (B) option is not a csv.writer parameter; encoding is handled by the underlying file object passed to the writer, typically via open(). The buffer_size (C) option is likewise not a csv.writer parameter; buffering is controlled by the file object's buffering argument in open(), not by the CSV writer.

Answer

encoding

Answer

buffer_size

Question 2

You are using configparser and want to access a value that might not exist, but provide a default value if it is missing. Which method is most appropriate?

Accepted Answer

parser.get('section', 'option', fallback='val'). The get() method accepts a 'fallback' argument to return a default value if the option is missing.

Answer

parser.get('section', 'option', default='val')

Answer

parser.get_or_default('section', 'option', 'val')

Answer

parser.exists('section', 'option') ? ...

Answer

parser.get('section', 'option') or 'val'

Question 3

Which THREE of the following are valid methods of the xml.etree.ElementTree.Element class?

Accepted Answer

find(). The xml.etree.ElementTree.Element class provides find(), append(), and set() as valid instance methods. find(match) searches the element's direct children for the first subelement matching the tag or path and returns it (or None), which is a core Element API method. append(subelement) adds a child Element to the end of the element's list of children, and set(key, value) sets an attribute on the element, both being standard Element methods. write() is not an Element method; it belongs to the ElementTree class (ElementTree.write(file, encoding, xml_declaration, ...)), which serializes the whole tree to a file. to_string() is also not an Element method; serialization to a string is done via xml.etree.ElementTree.tostring(element) (no underscore), so option E is invalid.

Answer

write()

Answer

to_string()

Question 4

Which TWO of the following are true about the sqlite3.Cursor object?

Accepted Answer

It can be used as an iterator to fetch rows.. Option A is correct because a sqlite3.Cursor implements the iterator protocol, so you can loop over it directly (e.g., 'for row in cursor:') to fetch rows one at a time from the result set. Option B is correct because the Cursor object provides the execute(), executemany(), and executescript() methods that are used to run SQL statements against the database. Option C is incorrect because transaction handling is a property of the Connection object, not the Cursor; SELECT statements do not automatically open a transaction in the way described. Option D is incorrect because a single Cursor can be reused for multiple sequential queries, and multiple cursors can exist on one connection. Option E is incorrect because connection state (such as open/closed status and transaction control) is tracked by the sqlite3.Connection object, not the Cursor.

Answer

It automatically creates a transaction for every SELECT.

Answer

It is limited to one active query.

Answer

It keeps track of the connection state.

Question 5

Which TWO of the following are valid ways to define a configuration option in configparser?

Accepted Answer

parser['section']['option'] = 'value'. Option A is correct because configparser supports the mapping-style interface, so assigning parser['section']['option'] = 'value' creates or updates the option 'option' in 'section' with the string 'value'. Option D is correct because the ConfigParser.set(section, option, value) method is the explicit API for setting an option's value within a section, and it requires the section to already exist. Options B, C, and E are not valid configparser methods: add_option, write, and insert do not exist with those signatures — write() actually writes the configuration to a file-like object, and there is no add_option or insert method for defining options.

Answer

parser.add_option('section', 'option', 'value')

Answer

parser.write('section', 'option', 'value')

Answer

parser.insert('section', 'option', 'value')

Question 6

Which TWO of the following are required to successfully write a row to a CSV file?

Accepted Answer

An instance of csv.writer.. To write a row to a CSV file with Python's csv module, you must first create an instance of csv.writer (option B), because csv.writer wraps a file-like object and provides the writerow()/writerows() methods that perform the CSV formatting and writing. You also need a file object opened in write mode (option E), such as one returned by open('file.csv', 'w', newline=''), since csv.writer writes to that underlying file object and cannot write to a path or a read-only handle. Option A is not required because the row data can be any iterable (e.g., tuple, generator), not strictly a list of strings, and the values need not all be strings since the writer converts them. Option C is incorrect because there is no csv.close() function; you close the underlying file object (or use a with block), not the csv module. Option D is incorrect because a predefined dialect is optional — csv.writer defaults to the 'excel' dialect if none is supplied.

Answer

A list of strings to write.

Answer

A call to csv.close().

Answer

A predefined dialect.

Question 7

You are using the sqlite3 module to insert a large number of rows into a table. You want to maximize performance by reducing the number of disk writes. Which approach is most effective?

Accepted Answer

Use a single transaction by executing BEGIN, then many INSERTs, then COMMIT.. Batching many INSERTs into a single transaction minimizes disk I/O and is the most effective way to speed up bulk inserts in sqlite3. Autocommit or frequent commits increase overhead. Using a single cursor also helps, but the transaction grouping is the key factor.

Answer

Set connection.isolation_level = None and execute each INSERT individually.

Answer

Set the connection's isolation_level to 'DEFERRED' and commit after every insert.

Answer

Create a new cursor for each INSERT statement.

Question 8

You are writing a Python script that must read a configuration file in TOML format. Which module from the Python Standard Library should you use?

Accepted Answer

tomllib. tomllib is the Standard Library module for reading TOML files, added in Python 3.11. It correctly parses TOML syntax and returns native Python types. Other modules like configparser, json, or yaml are either for different formats or not in the standard library.

Answer

yaml

Answer

configparser

Answer

json

Question 9

You are using the csv module to read a file that contains fields with embedded newlines and commas. Which TWO of the following statements about the csv.reader are correct? (Choose two.)

Accepted Answer

The csv.reader requires the file to be opened with newline='' to correctly handle embedded newlines.. The csv.reader requires newline='' when opening the file to handle embedded newlines correctly, and it always returns rows as lists of strings. It does not auto-detect delimiters or convert types, and it supports any encoding. These behaviors are essential for correct CSV parsing.

Answer

The csv.reader can only read files encoded in UTF-8.

Answer

The csv.reader automatically converts numeric fields to int or float.

Answer

The csv.reader automatically detects and uses the correct delimiter based on the file content.

Question 10

You are writing a Python application that must parse a configuration file where a value spans multiple lines, such as a long list of email addresses separated by newlines. You decide to use the configparser module. Which of the following correctly describes how to include a multi-line value in the configuration file?

Accepted Answer

Indent continuation lines with whitespace; they will be joined with newline characters.. In configparser, multi-line values are specified by indenting continuation lines. The parser then joins these lines with newline characters. This is the standard way to include values that span multiple lines, such as lists. The other options incorrectly suggest backslashes, triple quotes, or semicolons, which are not part of the INI format syntax for continuation.

Answer

Separate lines with a semicolon to indicate continuation.

Answer

Enclose the value in triple quotes to allow multiple lines.

Answer

Use a backslash at the end of each line to indicate continuation.

Question 11

You are building a Python script that needs to create a ZIP archive containing files from a directory. You want to preserve the directory structure inside the archive. Which approach using the zipfile module correctly adds the file '/data/reports/summary.txt' as 'reports/summary.txt' inside the archive?

Accepted Answer

zipf.write('/data/reports/summary.txt', arcname='reports/summary.txt'). The zipfile.ZipFile.write() method accepts an arcname parameter that specifies the name of the file inside the archive. To preserve a directory structure, you provide a relative path as the arcname, such as 'reports/summary.txt'. This ensures the file is stored with that exact path, regardless of its location on the filesystem.

Answer

zipf.write('/data/reports/summary.txt')

Answer

zipf.add('/data/reports/summary.txt', 'reports/summary.txt')

Answer

zipf.write('/data/reports/summary.txt', arcname='summary.txt')

Question 12

You are building a configuration manager that reads an INI file. A section contains the key-value pair `timeout = 30`. You need to retrieve the value as an integer, but if the key is missing, you want to get 60 without raising an exception. Which code snippet achieves this using the `configparser` module?

Accepted Answer

config.getint('section', 'timeout', fallback=60). The `getint` method of the `ConfigParser` class retrieves a value and converts it to an integer. It accepts a `fallback` argument that is returned if the key is not found, preventing a `NoOptionError`. This is the standard way to handle optional integer settings in INI files.

Answer

int(config.get('section', 'timeout', fallback=60))

Answer

config['section'].getint('timeout', 60)

Answer

config.getint('section', 'timeout', default=60)

Question 13

You are developing a Python script that needs to determine the absolute path of a file located in a directory relative to the script's location. You decide to use the os.path module. Which of the following functions should you use to obtain the absolute path without resolving symbolic links?

Accepted Answer

os.path.abspath(). os.path.abspath() computes an absolute path by combining the current working directory with the given path, normalizing it without resolving symbolic links. This matches the requirement. os.path.realpath() would resolve symlinks, os.path.normpath() only normalizes, and os.path.join() only concatenates components. Thus, abspath is the correct choice.

Answer

os.path.normpath()

Answer

os.path.realpath()

Answer

os.path.join()

Question 14

You are building a Python application that uses the shelve module to store persistent data. You want to ensure that the database file is updated correctly and that you can access keys as attributes. Which TWO of the following statements about the shelve module are true? (Choose two.)

Accepted Answer

By default, shelve uses the pickle module to serialize values.. The shelve module provides a persistent, dictionary-like object. It uses pickle to serialize values by default, allowing storage of complex Python objects. However, it does not automatically sync after each assignment; you must call sync() or close the shelf. Keys are accessed via subscription, not attributes, and it is not thread-safe. Therefore, the true statements are about the dictionary-like interface and pickle serialization.

Answer

shelve automatically synchronizes changes to disk after every assignment.

Answer

You can access shelf keys as attributes using dot notation.

Answer

The shelve module is thread-safe by default.

Question 15

You are using the `json` module to serialize a custom object that contains a `datetime.date` attribute. When you call `json.dumps(obj)`, you get a `TypeError: Object of type date is not JSON serializable`. Which approach correctly allows serialization while preserving the date as an ISO 8601 string?

Accepted Answer

Create a subclass of `json.JSONEncoder` and override its `default` method to return `obj.isoformat()` for `date` instances, then pass it to `json.dumps` via the `cls` parameter.. The `json` module's `JSONEncoder` class provides a `default` method that is called for objects that are not natively serializable. By subclassing and overriding this method, you can return a serializable representation, such as an ISO 8601 string for dates. Passing this encoder class to `json.dumps` via the `cls` argument enables the custom behavior.

Answer

Implement a `__json__` method on the custom object that returns a serializable dictionary, and `json.dumps` will call it automatically.

Answer

Use `json.dumps(obj, default=str)` to automatically convert any non-serializable object to its string representation.

Answer

Convert the `date` attribute to a string using `obj.date.isoformat()` before calling `json.dumps`, and then convert it back when deserializing.