The __init__() Method in Python

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The __init__() Method in Python

In Python, every class can have a special method named __init__().

This method is automatically executed whenever a new object is created from a class.

The main purpose of __init__() is to:

• Initialize object data
• Assign values to object attributes
• Perform setup tasks during object creation

How __init__() Works

When you create an object, Python immediately calls the __init__() method and passes the provided arguments to it.

Example: Initialize Object Attributes

class User: def __init__(self, username, level): self.username = username self.level = level u1 = User("alex", 5) print(u1.username) print(u1.level)

Output:

alex
5

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Here:

• __init__() assigns initial values to the object
• Attributes are created at the time of object construction

Automatic Execution of __init__()

You do not need to call __init__() explicitly.

Python runs it every time a new instance of the class is created.

Creating Objects Without __init__()

If a class does not define an __init__() method, attributes must be assigned manually.

Example: Manual Attribute Assignment

class User: pass u1 = User() u1.username = "sam" u1.level = 2 print(u1.username) print(u1.level)

Output:

sam
2

Try it Yourself

This approach works but is error-prone and harder to manage, especially in large programs.

Why __init__() Is Important

Using __init__():

• Ensures objects are created in a valid state
• Reduces repetitive code
• Improves readability and reliability

Using Default Values in __init__()

You can provide default values for parameters, making them optional during object creation.

Example: Default Parameter Value

class Account: def __init__(self, owner, balance=0): self.owner = owner self.balance = balance a1 = Account("Ravi") a2 = Account("Meera", 5000) print(a1.owner, a1.balance) print(a2.owner, a2.balance)

Output:

Ravi 0
Meera 5000

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Multiple Parameters in __init__()

The __init__() method can accept any number of parameters, depending on your class design.

Example: Multiple Attributes

class Employee: def __init__(self, name, role, department, salary): self.name = name self.role = role self.department = department self.salary = salary e1 = Employee("Anita", "Developer", "IT", 75000) print(e1.name) print(e1.role) print(e1.department) print(e1.salary)

Output:

Anita
Developer
IT
75000

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