# Object Oriented Programming

* Python, a popular programming language, offers a powerful feature called object-oriented programming (OOP).
    
* This approach allows developers to organize their code in a way that makes it easier to understand and reuse.
    
* Central to OOP in Python are classes, which act as blueprints for creating objects with shared characteristics and behaviors.
    

### Classes

* They are abstract and blueprint only. For example, Let's imagine a map of your house before you construct it is **class**.
    
* One class can have many objects like we can make multiple houses with the help of the same map.
    
    ```python
    class Classname:
        #your variables and functions
    ```
    

### Objects

* When the **house** is constructed from it then it is considered an object which exists and is real.
    
* Similarly, various features of house such as **color, furniture, number of rooms**, etc are also objects.
    
    ```python
    object_name = Classname()
    ```
    

### **Some examples to create classes and objects :**

```python
#creating class
class Number:
    def sum(self):
        return self.a + self.b

obj = Number()
obj.a = 10
obj.b = 10
s = obj.sum()#calling sum() with 
print(s) # Object = 20
```

### **Creating a class with constructor(**`__init__())`

```python
class Map:
    #instance method because it is bound to instance of class
    category = 'house_category'
    def __init__(self, color, num_rooms, area):
        #declaring instance variable
        self.color = color
        self.num_rooms = num_rooms
        self.area = area

# Creating different objects for the House class
house1 = Map("Green", 10, 2500)#object1
house2 = Map("Orange", 2, 1000)#object3

print(house1.color) # Output = Green
print(house2.num_rooms) # Output = 2
```

### \_\_init\_\_() constructor

* `__init__` method is the **constructor** in Python which is **automatically called** at the time of object creation.
    
* `__init__` is the **instance method** because it is bound to the instance of the class.
    
* Various variable inside this method is **instance variable** because it is associated with the object(`self`)
    
* category variable or attributes outside init consctuctor is class variable.
    

### Self keyword

* `self` parameter is automatically passed as the first argument whenever the method is called.
    
* By convention, it is named `self`, although you can technically use any valid variable name in its place.
    
* `self` is the object in python.
    
* `self` parameter allows you to access and manipulate the instance's attributes and call other instance methods within the class. For instance, self.**attribute\_name** or self.**function\_name**()