PCAP-31-03 4.6 Construct and Initialize Objects PCAP-31 Practice Questions (Page 8)

Questions 36–40

1. 36expert · medium

   A developer is debugging a `Counter` class. The constructor is `def __init__(self, start=0): self.count = start`. They create `c1 = Counter(5)` and `c2 = Counter()`. Later, they execute `c1.count += 1`. What is the value of `c2.count`?

   • A5
   • B0
   • C1
   • D6
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2. 37expert · medium

   A developer writes a class `Person` with `def __init__(self, name): self.name = name`. They then write `p = Person('Alice')` and `q = Person(name='Bob')`. Which statement is true?

   • ABoth `p` and `q` are valid, but `p.name` is 'Alice' and `q.name` is 'Bob'.
   • B`q` is valid, but `p` raises a TypeError because positional arguments are not allowed.
   • CBoth `p` and `q` are valid instances with `name` attributes set to 'Alice' and 'Bob' respectively.
   • D`p` is valid, but `q` raises a TypeError because keyword arguments are not allowed.
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4. 38expert · medium

   A developer defines `class Widget:` with no `__init__`. They then write `w = Widget()`. Later, they try to access `w.size`. What happens?

   • A`w.size` returns `None` because the default constructor sets all attributes to `None`.
   • B`w.size` returns an empty string because the default constructor initializes attributes to empty values.
   • CAn AttributeError is raised because `size` was never set.
   • D`w.size` returns the class attribute `size` if it exists, otherwise it raises an error.
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5. 39expert · hard

   A developer is designing a `Temperature` class. They want the constructor to accept a value and a scale ('C' or 'F'), and store the value in Celsius internally. Which constructor implementation correctly converts Fahrenheit to Celsius?

   • Adef __init__(self, value, scale='C'): if scale == 'F': self.celsius = (value - 32) * 5 / 9 else: self.celsius = value
   • Bdef __init__(self, value, scale='C'): self.celsius = value
   • Cdef __init__(self, value, scale='C'): if scale == 'F': self.celsius = value else: self.celsius = (value - 32) * 5 / 9
   • Ddef __init__(self, value, scale='C'): self.value = value self.scale = scale
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6. 40application · easy

   A developer defines a class `User` with `def __init__(self, name, age):` and then writes `u = User('Alice', 30)`. What is the immediate effect of this line?

   • AA new `User` instance is created, but `__init__` is not called because the class already has a default constructor.
   • BThe line creates a dictionary with keys `name` and `age` and assigns it to `u`.
   • CThe `__init__` method is called with `name='Alice'` and `age=30`, but `self` is not passed because it is implicit.
   • DA new `User` instance is created and `__init__` is called with `self` bound to that instance, `name='Alice'`, and `age=30`.
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