Defining a function

def keyword, followed by the function name and parentheses (). Any parameters go inside the parentheses.

def function_name(parameters):
    """
    Docstring: Brief description of the function
    """
    # Function body
    # Code block
    return value

Calling a function

function name followed by parentheses ()

function_name(arguments)

Parameters and Arguments

The values you pass into a function when calling it are called arguments. The variables listed in the function definition are called parameters.

def greet(name, greeting="Hello"):  # name is a parameter, greeting is a parameter with a default value
    print(f"{greeting}, {name}!")

greet("Alice")  # Alice is the argument
greet("Bob", "Hi")  # Bob is the argument, Hi is the argument

\Arbitrary Arguments (args)*

If you don't know how many arguments will be passed to a function, you can use the *args syntax to collect them into a tuple.

def print_numbers(*args):
    for arg in args:
        print(arg)

print_numbers(1, 2, 3)  # Output: 1 2 3

\*Keyword Arguments (kwargs)*

You can also collect arbitrary keyword arguments into a dictionary using the **kwargs syntax.

def print_info(**kwargs):
    for key, value in kwargs.items():
        print(f"{key}: {value}")

print_info(name="Alice", age=25)  # Output: name: Alice, age: 25

Lambda Functions

Python supports the creation of anonymous functions (lambda functions). These are small, one-line functions.

square = lambda x: x ** 2
print(square(5))

Python Classes/Objects

Python is an object oriented programming language.

Almost everything in Python is an object, with its properties and methods.

A Class is like an object constructor, or a "blueprint" for creating objects.

Define Python Class

We use the classkeyword to create a class in Python. For example,

class ClassName:
    # class definition

Here, we have created a class named ClassName.

Let's see an example,

class Room:
    length = 0
    breadth = 0

    def area(self):
        return self.length * self.breadth

1. Room - the name of the class

2. length and breadth are the attributes of the class

3. area is the method of the class

Understanding init method

 def __init__(self, length=0, breadth=0):
        self.length = length
        self.breadth = breadth

It is the constructor of the class Room. Meaning it is initialized everytime when the class is called(when object is created)

class Room:


    # Constructor
    def __init__(self, length=0, breadth=0):
        self.length = length
        self.breadth = breadth

    # Instance methods
    def area(self):
        return self.length * self.breadth

    def perimeter(self):
        return 2 * (self.length + self.breadth)

    def print_details(self):
        print(f"Room dimensions: {self.length} x {self.breadth} meters")
        print(f"Area: {self.area()} square meters")
        print(f"Perimeter: {self.perimeter()} meters")



# Creating instances (objects) of the Room class
room1 = Room(5, 4)
room2 = Room(3, 3)

# Calling instance methods
room1.print_details()
print()
room2.print_details()
print()

Inheritance:

class Room:
    # Class attribute
    num_rooms = 0

    # Constructor
    def __init__(self, length=0, breadth=0):
        self.length = length
        self.breadth = breadth
        Room.num_rooms += 1

    # Instance methods
    def area(self):
        return self.length * self.breadth

    def perimeter(self):
        return 2 * (self.length + self.breadth)

    def print_details(self):
        print(f"Room dimensions: {self.length} x {self.breadth} meters")
        print(f"Area: {self.area()} square meters")
        print(f"Perimeter: {self.perimeter()} meters")

# Child class inheriting from Room
class Bedroom(Room):
    def __init__(self, length, breadth, num_beds):
        super().__init__(length, breadth)
        self.num_beds = num_beds

    def print_details(self):
        super().print_details()
        print(f"Number of beds: {self.num_beds}")

# Creating instances of the classes
room1 = Room(5, 4)
bedroom1 = Bedroom(4, 3, 2)

# Calling instance methods
room1.print_details()
print()
bedroom1.print_details()