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

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import urllib.request

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​

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​

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def capture_price():

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    page = urllib.request.urlopen("https://cors.bridged.cc/http://beans.itcarlow.ie/prices-loyalty.html")

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    text = page.read()

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    where = text.find("$")

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    start = where + 1

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    end = start + 4

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    return float(text[start:end])

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​

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option = input("Do you want to buy now? (Y/N)")

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if option.lower() == "y":

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    price = capture_price()

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    print("Buy! Price: %5.2f" % price)

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else:

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    price = 99.99

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    while price >= 4.74:

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        price = capture_price()

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    print("Buy! Price: %5.2f" % price)

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​

Activity: 3.2.1 ActiveCode (ac_l35_3_en)

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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