Printing "none" after joining a list

Question

I have a class called deck, it stores a list of integers, I need to print those integers so I used

def printdeck(self):
    print(" ".join(map(str,self.deck)))

It works and all but it returns "none" after use. I'd like it not to print "none" but I've no idea how to stop that. Any ideas?

Are you printing the return value too? The code shown here does **not** print `None`. — Martijn Pieters, May 08 '16 at 21:23
Either return a string (`return " ".join(map(str,self.deck))`), which you then print `(print(deck.printdeck())`, *or* just leave the printing to the method and ignore the return value. — Martijn Pieters, May 08 '16 at 21:24
@MartijnPieters My guess is that this is being used in a shell, and thus he is seeing "None" being printed after calling the function. — Rushy Panchal, May 08 '16 at 21:24
@RushyPanchal: the Python interactive interpreter does not print expression results if they produce `None`. — Martijn Pieters, May 08 '16 at 21:26
see http://stackoverflow.com/questions/7664779/python-what-is-the-formal-difference-between-print-and-return or it's duplicate. — Tadhg McDonald-Jensen, May 08 '16 at 21:26
@MartijnPieters Ah, did not realize this. Will edit my answer accordingly. — Rushy Panchal, May 08 '16 at 21:27
This should instead be a duplicate of [Why is "None" printed after my function's output?](/q/7053652). — Karl Knechtel, Aug 17 '22 at 05:10

score 0 · Accepted Answer · answered May 08 '16 at 21:23

This is because you're not actually returning anything, so the function defaults to returning None.

A better alternative is to return your joined string, and then print that result:

def getdeck(self):
    return " ".join(map(str,self.deck))

print(getdeck())

Note that if you keep your function in this form:

def printdeck(self):
    print(" ".join(map(str,self.deck)))

it will work as you intend to, but it returns None. If you print the return value, then you will see None being printed.

You could keep it the second way but return an empty string to avoid returning None. — Rich, Jan 16 '20 at 05:13

1 Answers1