1 Python Functions

1. What is a Function?

A function is a block of code that does a specific job.

In simple words:
👉 A function is like a machine
👉 You give input
👉 It does work
👉 It gives output

2. Why Use Functions?

Functions help us:

  • Avoid repeating code

  • Keep program clean

  • Make code easy to understand

3. Create a Simple Function

We use the def keyword to create a function.

Example


 

4. Function with Parameters

Parameters are values passed into a function.

Example


 

5. Function with Multiple Parameters

Example


 

6. Function with Return Value

 

Example


 

7. Function Without Return

Example


 

8. Default Parameter Value

Example


 

9. Keyword Arguments

Example


 

10. Function with List

Example


 

11. Function Inside Function

Example


 

12. Common Beginner Mistakes

❌ Forgetting to Call Function


 

✔ Must call:


 

❌ Using Print Instead of Return


 

✔ Use return when value is needed.


13. Simple Practice Examples

Example 1: Check Even Number


 

Example 2: Find Square


 

Example 3: Welcome Message


 

14. Summary (Python Functions)

✔ Use def to create function
✔ Functions reduce repetition
✔ Parameters pass data
return gives output
✔ Functions make code clean

📘 Perfect for Beginner eBook

This chapter is ideal for:

  • Python beginner books

  • School & college students

  • Self-learners

If you want next, I can write:

  • Function Arguments

  • Lambda Functions

  • Recursion

  • Function Exercises

Just tell me 😊

You may also like...