PCAP Practice Test 22 — 15 Questions

Question 1

Which TWO statements about static methods (@staticmethod) are correct?

Accepted Answer

They do not receive an implicit first argument.. Static methods in Python do not receive an implicit first argument like `self` (for instance methods) or `cls` (for class methods). They behave like plain functions but belong to a class's namespace, and are called without any automatic parameter injection.

Answer

They can access instance attributes via self.

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They can access class variables only via cls.

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They can only be defined inside a metaclass.

Question 2

Which TWO of the following are valid ways to use string formatting in Python? (Choose two.)

Accepted Answer

"Hello {0}".format("World"). The `str.format()` method with positional index `{0}` is a valid way to insert the argument `"World"` into the string, producing `"Hello World"`. This is a core feature of Python's string formatting, introduced in Python 2.6, and is explicitly tested in the PCAP exam.

Answer

"Hello $s" % "World"

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f"Hello {world}"

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"Hello {name}".format("World")

Question 3

A class has a method that does not access any instance or class data. What decorator should be used to define it as a utility method that can be called on the class itself without requiring an instance?

Accepted Answer

@staticmethod. A @staticmethod decorator defines a method that does not receive an implicit first argument (self or cls). It can be called on the class itself without creating an instance, making it suitable for utility functions that do not access instance or class data. This matches the requirement.

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@property

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@abstractmethod

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@classmethod

Question 4

Match each variable scope to its description.

Accepted Answer

Local: Variables defined inside a function.. The LEGB rule defines scope lookup order: Local, Enclosing, Global, Built-in. Correct matches are Local (inside function), Enclosing (outer function), Global (module level). Built-in consists of Python's predefined names.

Answer

Built-in: Variables defined at the top level of a module.

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Local: Variables defined in an enclosing function.

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Global: Predefined names like print and len.

Question 5

Match each Python operator to its precedence level (1=highest).

Accepted Answer

**: Level 1 (highest). Operator precedence from highest to lowest: ** (exponent) > *, /, //, % (multiplicative) > +, - (additive).

Answer

*: Level 1

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+: Level 2

Question 6

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')

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b'\xc3\xa9'.tostring()

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

Question 7

A programmer wants to ensure that a class attribute is the same for all instances and can be accessed via the class name. Which type of variable should be defined?

Accepted Answer

Class variable. A class variable in Python is defined directly within the class body (outside any method) and is shared across all instances. It can be accessed via the class name (e.g., `ClassName.var`) or through any instance, ensuring the same value for all objects.

Answer

Global variable

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Instance variable

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Local variable inside a method

Question 8

What is the most likely cause of this error?

Accepted Answer

Circular import between __init__.py and submodule.py.. A circular import occurs when `__init__.py` and `submodule.py` attempt to import each other (directly or indirectly) before either module is fully initialized. In Python, when a module is being imported, it is added to `sys.modules` as a partially initialized module; if another module tries to import it during that time, it may receive an incomplete or empty module object, leading to an `ImportError` or `AttributeError`. This is a common cause of import failures in packages where initialization logic in `__init__.py` depends on submodules that themselves import from the package root.

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The package's __init__.py is missing a __all__ definition.

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The main.py is executed from a directory outside the package.

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The submodule.py attempts to import a module named '__init__' which is reserved.

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The submodule.py uses an invalid relative import syntax.

Question 9

Which THREE of the following are true about Python's object-oriented programming features?

Accepted Answer

Python supports multiple inheritance. Python's class hierarchy supports multiple inheritance, allowing a class to inherit from more than one parent class. This is a core feature of Python's object-oriented programming model, implemented via the C3 linearization algorithm (Method Resolution Order, or MRO) to resolve method and attribute lookups unambiguously.

Answer

Python supports method overloading based on argument types

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Python enforces access modifiers like private and protected

Question 10

Which TWO of the following are built-in exceptions in Python? (Select exactly 2.)

Accepted Answer

ValueError. ValueError is a built-in exception in Python, raised when a built-in operation or function receives an argument with the correct type but an inappropriate value, such as int('abc'). It is part of Python's standard exception hierarchy and does not require any import.

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InputError

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DataError

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CustomError

Question 11

A programmer wants to create a package named 'analytics' with subpackages 'statistics' and 'ml'. Which directory structure correctly defines these packages?

Accepted Answer

analytics/ (__init__.py), analytics/statistics/ (__init__.py), analytics/ml/ (__init__.py). In Python, a directory is recognized as a package only if it contains an `__init__.py` file (even if empty). To create the 'analytics' package with 'statistics' and 'ml' subpackages, each directory must have its own `__init__.py`. Option D correctly places `__init__.py` in all three directories: `analytics/`, `analytics/statistics/`, and `analytics/ml/`.

Answer

analytics/, analytics/statistics/ (__init__.py), analytics/ml/ (__init__.py)

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analytics/ (__init__.py), analytics/statistics/ (__init__.py), analytics/ml/ (__init__.py), analytics/__init__.py (file)

Answer

analytics/ (__init__.py), analytics/statistics/, analytics/ml/

Question 12

A programmer needs to write a function that reads a large binary file (over 1 GB) and returns its entire content as a bytes object. The function must handle the case where the path provided is actually a directory (IsADirectoryError) by returning an empty bytes object. Which implementation is most memory-efficient and correctly handles the directory case? Consider that reading the entire file into memory is acceptable for the business case.

Accepted Answer

Use 'with open(path, 'rb') as f: return f.read()' inside a try-except IsADirectoryError catch that returns b''.. It uses a try-except block specifically catching `IsADirectoryError`, which is raised when `open()` is called on a directory path. The `with` statement ensures the file is properly closed, and `f.read()` returns the entire content as a bytes object, which is memory-efficient for this use case (the file is read in one large allocation, avoiding overhead from chunking).

Answer

Use 'with open(path, 'rb') as f: return f.read()' inside a try-except OSError that returns b''.

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Use os.path.isfile(path) to check before opening; if not a file, return b''.

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Use 'with open(path, 'rb') as f: return [chunk for chunk in iter(lambda: f.read(1024), b'')]' inside a try-except IsADirectoryError.

Question 13

A company runs a data processing pipeline that reads CSV files from a network drive. Occasionally, the network drive is unreachable causing FileNotFoundError. The current code uses a bare except clause that catches all exceptions, which also masks programming errors like NameError. The lead developer wants to implement a more robust exception handling strategy. The requirement is to log the specific error (including the filename) and retry the operation up to 3 times with a 2-second delay between retries. If after 3 attempts the file is still inaccessible, the pipeline should skip the file and continue with the next one. Which approach best meets these requirements?

Accepted Answer

Use a try-except block catching OSError, with a retry loop that logs the error and continues after max retries.. It catches OSError, which is the parent class for file-related errors like FileNotFoundError, while still allowing programming errors like NameError to propagate. The retry loop with a 2-second delay and a maximum of 3 attempts satisfies the requirement, and after exhausting retries, the loop naturally continues to the next file, skipping the problematic one.

Answer

Use os.path.exists before opening the file, and if it returns False, log and skip.

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Use a try-except block catching Exception, with a retry loop and logging.

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Use a with statement; if an exception occurs, call the function recursively up to 3 times.

Question 14

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

Accepted Answer

1,234,567. The correct output is '1,234,567' because the format specifier '{:,}' uses the comma as a thousands separator in Python's string formatting. When applied to the integer 1234567, it inserts commas every three digits from the right, producing the locale-independent grouping.

Answer

1234567

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1.234.567

Answer

1 234 567