Section 6 overview

So far you've written code that runs top to bottom. Functions let you package a chunk of code, give it a name, and reuse it whenever you want — instead of copying and pasting.

A function is a named, reusable block of code. You define it once, then call it as many times as you need.

What you'll learn

Define and call your own functions
Pass data in with parameters and get results back with return
Give parameters default values so callers can leave them out

Python

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

greet()   # Hello!
greet()   # Hello!

Functions keep your programs short, readable, and easy to change — fix the logic in one place and every call gets the fix.

Key takeaways

A function is a named, reusable block of code.
You define a function once and call it many times.
This section covers defining, calling, parameters, return values, and defaults.