Python Dataclasses Exercises With Answers

Which decorator turns a class into a dataclass?

1. @property
2. @dataclasscorrect
3. @staticmethod
4. @classmethod

Answer: @dataclass

Why: The dataclass decorator reads the annotated fields and generates common methods.

What does a dataclass generate by default?

1. A database table
2. __init__, __repr__, and __eq__correct
3. A JSON file
4. Only __init__

Answer: __init__, __repr__, and __eq__

Why: The default dataclass provides initialization, display, and value equality.

What does frozen=True prevent?

1. Attribute assignmentcorrect
2. Creating instances
3. Calling asdict
4. Reading fields

Answer: Attribute assignment

Why: A frozen dataclass raises an error when an attribute is assigned after creation.

What does the program output?

from dataclasses import dataclass
@dataclass
class P:
    x: int
print(P(1))

1. 1
2. P(1)
3. {'x': 1}
4. P(x=1)correct

Answer: P(x=1)

Why: The generated repr includes the class name and field values.

Complete the module that provides dataclass.

from ____ import dataclass

Answer: dataclasses

Why: The decorator is imported from dataclasses.

Complete the field annotation.

from dataclasses import dataclass
@dataclass
class P:
    x: ____

Answer: int

Why: x is declared as an integer field.

Complete the default value for active.

from dataclasses import dataclass
@dataclass
class U:
    name: str
    active: bool = ____

Answer: True

Why: active defaults to True when it is omitted.

Complete the function that converts the instance to a dictionary.

from dataclasses import dataclass, asdict
@dataclass
class P:
    x: int
p = P(2)
print(____(p))

Answer: asdict

Why: asdict returns a plain dictionary of field names and values.

What appears on the screen?

from dataclasses import dataclass
@dataclass
class P:
    x: int
print(P(2))

Answer: P(x=2)

Why: The generated repr shows the class and the field, P(x=2).

What is printed?

from dataclasses import dataclass
@dataclass
class P:
    x: int
print(P(1) == P(1))

Answer: True

Why: Dataclasses compare their fields, so two instances with x=1 are equal.

What is the output?

from dataclasses import dataclass
@dataclass
class U:
    name: str
    active: bool = True
print(U("Ada").active)

Answer: True

Why: The default active value is True, and the instance exposes it.

What does this code print?

from dataclasses import dataclass, asdict
@dataclass
class P:
    x: int
print(asdict(P(2)))

Answer: {'x': 2}

Why: asdict returns a plain dictionary with the field value.