Python! Functions | Lectures 8

Lets Start Python Programming For Beginners to advanced. Functions – Reusable Code Blocks, Lectures 8

🐍 Lecture 8: Functions – Reusable Code Blocks

🎯 Goal

By the end of this lecture, you will:

• Understand what a function is and why it’s useful.
• Be able to define and call your own functions.
• Use parameters and return values to make functions more powerful.
• Practice writing simple functions like greet() or add().

🧠 What Is a Function?

A function is like a mini-program inside your code.

It helps you:

• Organize your code
• Reuse code without typing it again and again
• Make your programs easier to read and fix

Think of a function like a magic box that does one specific job.

📦 Example:

def greet():
    print("Hello!")

This defines a function called greet() that says “Hello!” when used.

🔧 How to Define a Function

To create a function, we use the keyword def, followed by the name and parentheses ().

Syntax:

def function_name():
    # Code goes here

Example:

def say_hi():
    print("Hi there!")

say_hi()

👉 Output:

Hi there!

🧒 Kids Corner: A function is like a recipe. Once you write it, you can use it anytime — just like making cookies over and over!

🗣️ Giving Your Function Information – Parameters

You can give your function extra info using parameters (like telling it what to say or do).

Example:

def greet(name):
    print(f"Hello, {name}!")

greet("Alice")
greet("Bob")

👉 Output:

Hello, Alice!
Hello, Bob!

Here, "Alice" and "Bob" are arguments — the actual values passed into the function.

📦 Getting an Answer Back – Return Values

Sometimes, you want your function to give back a result.

Use return to send a value back.

Example:

def add(a, b):
    return a + b

result = add(3, 5)
print("The sum is:", result)

👉 Output:

The sum is: 8

Now you can store or use the result somewhere else in your program.

🔄 Practice Time!

Write a function that:

• Takes a person’s name
• Says hello and tells them the square of 5

💡 Sample Code:

def welcome(name):
    print(f"Welcome, {name}!")
    print("The square of 5 is", 5 * 5)

welcome("Emma")

👉 Output:

Welcome, Emma!
The square of 5 is 25

🚀 Challenge (Optional)

Make a function that calculates the area of a rectangle.

def area(width, height):
    return width * height

print("Area of rectangle:", area(4, 6))

👉 Output:

Area of rectangle: 24

Try adding another function for perimeter!

🧒 Kids Corner

🧠 Imagine you have a robot friend who knows how to tie shoes.
Every time someone needs help tying shoes, you say:

“Robot, tie shoes!”

That’s exactly what a function does — it lets you reuse a task easily!

🤖 Robot says:

Shoes tied! Ready to go!

📌 Summary

• Use def to define a function.
• Call the function with its name and parentheses.
• Pass information using parameters.
• Use return to get a result from a function.
• Functions help organize code and avoid repetition.

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Python Programming For Beginners To Advanced

Python Programming For Beginners! Lecture 1

Python Programming! Variables and Data Types | Lectures 2

Python Programming! Input And Output | Lectures 3

Python Programming! Operators in Python Lectures 4

Python Programming! Conditional Statements Lectures 5

Python! Loops For and While | Lectures 6

Python! Building A Mini Game | Lectures 7

Python! Functions | Lectures 8 

Python! Storing Multiple Values | Lectures 9