3. Program with functions

3.1. Functions

• Functions are shareable codes

• I define a name and call the function throughout the program

• The function must be defined before it can be called

• If you want to return a value to the subject that calls the function, you must use the return command

3.2. Program with functions

import urllib.request def capture_price(): page = urllib.request.urlopen("https://cors.bridged.cc/http://beans.itcarlow.ie/prices-loyalty.html") text = page.read() where = text.find("$") start = where + 1 end = start + 4 return float(text[start:end]) option = input("Do you want to buy now? (Y/N)") if option.lower() == "y": price = capture_price() print("Buy! Price: %5.2f" % price) else: price = 99.99 while price >= 4.74: price = capture_price() print("Buy! Price: %5.2f" % price)

3.3. There are no stupid questions

• Is the return command the same as printing? No, print() shows something on the screen, while return returns a value to the function caller.

• If there is no return inside the function, what does it return? It returns nothing: None. Should return always appear at the end of the function? Not always, depends on the logic of the function.

• Can a function return more than one value? Yes, including lists or dictionaries.

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