What are "dunder" methods? Give an example.

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"Dunder" methods (short for "double underscore" methods) are special methods in Python that begin and end with double underscores (__), like __init__, __str__, and __len__. They’re also known as magic methods or special methods.

These methods are used to:

• Customize the behavior of built-in operations

• Enable operator overloading

• Integrate your class with Python's core language features (like iteration, context managers, etc.)

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✅ Example:

python
class Book:
    def __init__(self, title):
        self.title = title

    def __str__(self):
        return f"Book: {self.title}"

book = Book("Fluent Python")
print(book)  # Output: Book: Fluent Python

• __init__: Initializes the object (like a constructor).

• __str__: Defines what str(obj) or print(obj) returns.

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🧠 Common Dunder Methods:

Method	Purpose
__init__	Constructor (called on object creation)
__str__	String representation (print(obj))
__repr__	Debug representation (repr(obj))
__len__	Length (len(obj))
__getitem__	Indexing (obj[i])
__iter__	Makes an object iterable
__eq__	Equality (==)

Dunder methods let your objects behave like built-in types and integrate seamlessly with Python’s syntax and idioms.

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