Parameters and return values

A parameter names an input inside a function. An argument is the value supplied by the caller. return sends a result back; printing only displays it and does not make it available for later calculation.

def total_minutes(sessions, minutes_each):
    return sessions * minutes_each

planned = total_minutes(3, 25)
print(planned)
print(total_minutes(2, 30) + 15)

75
75

Use a default argument

A default parameter supplies a value when the caller leaves that argument out. Put non-default parameters before default parameters.

def greet(name, greeting="Hello"):
    return f"{greeting}, {name}!"

print(greet("Sam"))
print(greet("Sam", "Welcome"))

Hello, Sam!
Welcome, Sam!

Why this works

Parameters are local names for values passed into a function. A function can return a result without displaying anything; the caller decides whether to print, store, or use it in another expression. A default argument is used only when that argument is omitted.

Practice

Write a function that accepts hours and minutes and returns the total number of minutes. Call it with 1 and 30 and print the returned 90.

Try another case

What does total_minutes(2, 45) return in the lesson example?