how to declare classes in python code example

Example 1: create and use python classes

class Mammal:
    def __init__(self, name):
        self.name = name

    def walk(self):
        print(self.name + " is going for a walk")


class Dog(Mammal):
    def bark(self):
        print("bark!")


class Cat(Mammal):
    def meow(self):
        print("meow!")


dog1 = Dog("Spot")
dog1.walk()
dog1.bark()
cat1 = Cat("Juniper")
cat1.walk()
cat1.meow()

Example 2: declare class python

# To create a simple class:
class Shape:
  	def __init__():
      	print("A new shape has been created!")
      	pass
    
    def get_area(self):
		pass

# To create a class that uses inheritance and polymorphism
# from another class:
class Rectangle(Shape):
  
	def __init__(self, height, width): # The constructor
    	super.__init__()
        self.height = height
    	self.width = width

	def get_area(self):
      	return self.height * self.width

Example 3: class in python

class ComplexNumber:
    def __init__(self, r=0, i=0):
        self.real = r
        self.imag = i

    def get_data(self):
        print(f'{self.real}+{self.imag}j')


# Create a new ComplexNumber object
num1 = ComplexNumber(2, 3)

# Call get_data() method
# Output: 2+3j
num1.get_data()

# Create another ComplexNumber object
# and create a new attribute 'attr'
num2 = ComplexNumber(5)
num2.attr = 10

# Output: (5, 0, 10)
print((num2.real, num2.imag, num2.attr))

# but c1 object doesn't have attribute 'attr'
# AttributeError: 'ComplexNumber' object has no attribute 'attr'
print(num1.attr)