Mixed Deck — All PCAP Topics Flashcards

What does `str.strip()` do?

Answer: Removes leading and trailing whitespace

`strip()` removes whitespace (or specified characters) from both ends of the string.

How do you check if a key exists in a dictionary?

Answer: if key in dict:

The in keyword is used to check if a key exists in a dictionary

Which exception is raised when accessing an index that does not exist in a list?

Answer: IndexError

`IndexError` is raised when a sequence subscript is out of range.

What does `file.readlines()` return?

Answer: A list of strings, one per line

`readlines()` reads all lines and returns them as a list of strings including newline characters.

What is a decorator in Python?

Answer: A function that wraps another function to add behavior

A decorator is a callable that takes a function and returns a new function with added behavior.

What does the `zip()` function do?

Answer: Combines multiple iterables element-by-element into tuples

`zip()` pairs elements from multiple iterables into tuples, stopping at the shortest iterable.

What does the `__name__ == '__main__'` guard do?

Answer: Prevents code from running when the module is imported

Code under `if __name__ == '__main__':` runs only when the script is executed directly, not when imported.

Which exception is raised when you try to open a file that does not exist?

Answer: FileNotFoundError

`FileNotFoundError` is a subclass of `OSError` raised when a file or directory is not found.

Which built-in function is used to open a file in Python?

Answer: open()

The `open()` function opens a file and returns a file object for reading or writing.

What is encapsulation in object-oriented programming?

Answer: Bundling data and methods within a class

Encapsulation bundles data (attributes) and behavior (methods) together inside a class.

How do you raise a custom exception in Python?

Answer: raise Exception('msg')

Python uses the `raise` keyword to manually throw an exception.

What does `**kwargs` allow in a function definition?

Answer: Variable keyword arguments as a dictionary

`**kwargs` collects extra keyword arguments into a dictionary inside the function.

What does `all(iterable)` return if the iterable is empty?

Answer: True

`all([])` returns True by vacuous truth — there are no False elements in an empty sequence.

Which attribute of a function object holds the variables captured by its closure?

Answer: __closure__

`func.__closure__` is a tuple of cell objects, each holding the value of one variable captured from the enclosing scope.

How do you start a comment in Python?

Answer: B) #

In Python, comments are started with the # symbol.

What does the `super()` function do in Python?

Answer: Calls a method from the parent class

`super()` returns a proxy object that delegates method calls to the parent class.

What does `random.randint(1, 10)` return?

Answer: A random integer from 1 to 10 inclusive

`random.randint(a, b)` returns a random integer N such that a <= N <= b (both endpoints included).

What does the following code print?

Answer: 12

The range(3) function generates numbers from 0 to 2, and the for loop prints each number in this range.

Which of the following is used to define a function in Python?

Answer: def

The def keyword is used to define a function in Python.

How do you add a condition to a list comprehension to include only even numbers?

Answer: [x for x in range(10) if x%2==0]

A conditional list comprehension uses `if condition` at the end: `[x for x in iterable if condition]`.