Functions Basics

A Function is a block of reusable code that performs a specific task. Instead of writing the same code over and over, you wrap it in a function and call it whenever you need it.

Why use Functions?

1. Reusability: Write once, use many times.
2. Organization: Break complex programs into smaller, manageable chunks.
3. Readability: Giving a name to a block of code makes it easier to understand.

How Functions Work

When you call a function, Python jumps to that function's code, executes it, and then returns to where it was called.

Defining a Function

Use the def keyword followed by the function name and parentheses ().

Docstrings

It's best practice to include a Docstring (documentation string) immediately after the function definition to explain what it does.

Type Hints (Modern Python) 🎯

Type hints help document what types of data your function expects and returns. They don't enforce types but make code more readable.

Recursion: Functions Calling Themselves 🔄

A function can call itself! This is called recursion. It's useful for problems that can be broken down into smaller versions of themselves.

The pass Statement

Function definitions cannot be empty. If you want to define a function but write the code later, use pass.

Coding Challenge: FizzBuzz Function 🏆

Write a function fizzbuzz(n) that prints numbers from 1 to n, but:

• For multiples of 3, print "Fizz"
• For multiples of 5, print "Buzz"
• For multiples of both, print "FizzBuzz"

Quiz

Key Takeaways

✅ Use def name(): to define a function.
✅ Use name() to call it.
✅ Docstrings ("""...""") explain what the function does.
✅ Type hints (-> int) document expected types.
✅ Recursion is when a function calls itself.

What's Next?

Functions are boring without data! In the next lesson, we'll learn how to pass Parameters and Arguments to make them dynamic.

Keep coding! 🚀