The __init__ method in Python is a special (built-in) method known as the constructor.
It is automatically called when a new object of a class is created and is used to initialize the object’s attributes.
| Feature | Description |
|---|---|
| Purpose | Initializes an object’s attributes at the time of creation. |
| Syntax | def __init__(self, parameters): |
| Called Automatically | Yes, when a new instance of a class is created. |
| Special Method | One of Python’s “dunder” (double underscore) methods. |
| Return Type | Does not return anything (returns None by default). |
🧩 Example 1: Basic Use of __init__
class Person:
def __init__(self, name, age):
self.name = name # instance variable
self.age = age # instance variable
def show(self):
print(f"My name is {self.name} and I am {self.age} years old.")
# Creating object
p1 = Person("Dheeraj", 24)
p1.show()Output:
My name is Dheeraj and I am 24 years old.🧩 Example 2: Default Values in __init__
class Car:
def __init__(self, brand="Tesla", color="Black"):
self.brand = brand
self.color = color
car1 = Car()
car2 = Car("BMW", "Blue")
print(car1.brand, car1.color)
print(car2.brand, car2.color)Output:
Tesla Black
BMW Blue🧩 Example 3: Using __init__ for Computation During Initialization
class Rectangle:
def __init__(self, length, width):
self.area = length * width # Calculated at initialization
rect = Rectangle(5, 3)
print("Area of rectangle:", rect.area)Output:
Area of rectangle: 15In Summary:
__init__is the constructor method that initializes instance variables.- It is called automatically when an object is created.
- It helps in setting up the initial state of an object.
- It’s one of the most commonly used dunder (double underscore) methods in Python classes.