FAQ: Learn Python - What Good are Functions?

This community-built FAQ covers the “What Good are Functions?” exercise in Codecademy’s lessons on Python.

FAQs for the Codecademy Python exercise What Good are Functions?:

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I cant see how the program links the bill to the meal_cost given later? I expected some kinde of linking them like (meal_cost = bill) first…?

def tax(bill):
“”“Adds 8% tax to a restaurant bill.”""
bill *= 1.08
print “With tax: %f” % bill
return bill

def tip(bill):
“”“Adds 15% tip to a restaurant bill.”""
bill *= 1.15
print “With tip: %f” % bill
return bill

meal_cost = 100
meal_with_tax = tax(meal_cost)
meal_with_tip = tip(meal_with_tax)

I was wondering the same thing but looks like nobody answered.

here you define a function with a parameter named bill:

def tax(bill):

and here you call the function and provide an argument:

meal_with_tax = tax(meal_cost)

this is known as positional arguments, python will pass the value of the first argument to the first parameter.

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Specifically, with positional parameters, only the position within the parentheses is important.

def my_function(x, y, z):
    # code here involving variables x, y, z
    return some_thing

# Now call it
apple = 7
orange = 8
pear = 10
print(my_function(apple, orange, pear))

The interpreter will assign the value 7 to the function parameter x, 8 to y, and 10 to z, solely due to the fact that x, y, and z have the same relative positions within the parentheses as do apple, orange and pear in the calling statement. The variable names matter not at all.

If the original function declaration had contained a variable name along with a default value, as
def tax(bill = 1.00), then the original poster’s thought would have been valid, and the variable names would count. More on that here.

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Thank you, this clears up a lot! :slight_smile:

Thank you so much for the well-explained example. Helped a lot.

In this exercise, return command was used, but it wasn’t explained beforehand what does it do.

You can fiddle with the code, see if you can figure it out :slight_smile:

you could consider to continue with the course, return will be explained

or do you already want an explanation now?

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I think I will play around a little bit.

This is wrong. The tip should be calculated on the bill before tax. Think about it.

A very quick review of the first page returned by Dr. Google on the topic tilts about 60 - 40 on the side of post-tax tipping. At any rate, it’s certainly not a clear-cut majority either way

And a majority opinion, of course, is not necessarily right :P.

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So in this outcome we are tipping over the taxed amount.
It makes the end result 1% higher.
Is that correct?