Python Classes and Objects

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Python Classes and Objects

Object-Oriented Programming in Python starts with two key components: Classes and Objects.
Understanding these concepts is essential for writing clean, modular, and reusable code.

What is a Class?

A class is a blueprint or template used to create objects.
It defines:

Attributes → data (variables)
Methods → behavior (functions)

Think of a class as a design plan, and objects as the actual items created from that plan.

Syntax of a Class

```

hider
class ClassName:
# class attribute
attribute_name = value
# method
def method_name(self):
# method body
Pass

```

What is an Object?

An object is an instance of a class.
When you create an object:

Memory is allocated
The class blueprint becomes a usable entity

Each object can have different values for its attributes but shares the same structure.

Example: Creating a Class and Object

```
# Defining a class
class Student:
def __init__(self, name, roll):
self.name = name
self.roll = roll

def display(self):
print(f"Name: {self.name}, Roll: {self.roll}")

# Creating objects of the class
student1 = Student("Sahil", 101)
student2 = Student("Ravi", 102)

# Accessing methods
student1.display()
student2.display()
```

Understanding the Example

1. `class Student:`

Defines a new class named Student.

2. `init()` – Constructor

Automatically runs when a new object is created.
It initializes object attributes.

3. `self` keyword

Refers to the current object.
Used inside the class to access attributes and methods.

4. Objects:

```
hide
student1 = Student("Sahil", 101)
student2 = Student("Ravi", 102)

```

These are two separate instances of the Student class.

5. Calling Method

```
hide
student1.display()
```

Executes the method for that specific object.

Accessing Attributes

You can directly access object attributes using the dot (.) operator:

```

print(student1.name)
print(student2.roll)

```

Notes

A class groups related data and behavior together.
An object is a real-world entity created from a class.
The dot operator is used to access attributes and methods.
The __init__() method automatically runs during object creation.

Real-Life Example

class->Blueprint of a Car

Defines structure: engine, wheels, color.

Objects->Actuals cars

Car1 (Red, BMW)
Car2 (Blue, Tesla)
Car3 (Black, Audi)

Each car follows the same structure but has different values.

Python Classes and Objects