🧩 Functions, lesson 1 of 6
Defining your own functions
Name a block of code with def and run it whenever you need it.
9 min
1 exercise
2 quizzes
0/3 solved
Getting Python ready… examples can run in a moment.
A function is a named, reusable block of code.
You've already used plenty: print, len,
input. Now you'll write your own with def:
def name(parameters):
body
Defining a function only stores it. The body runs
when you call it: name(...).
Your first function
Delete both calls and run it: nothing is printed, because the body never runs.
Parameters are the input names in the def
line. Arguments are the actual values you pass
when calling. Arguments fill parameters in order.
Parameters
Call greet with your own name.
Receipt line
One function, many receipts. Change the format once and every line follows.
What does this print?
Missing an argument
The error message names the missing parameter: height.
Birthday card
Define a function birthday_card(name, age) that
prints two lines:
Happy birthday, Ana!
You are 30 today.
Then call it once to try it out.
What happens when Python reaches a def statement?