Python 返回函数返回 None 而不是 True

Question

I am trying to complete a task for my computer science class and I have a function that should be returning True but is returning None. I have not finished the code but this section should be working properly.

The code does look in the if statement as other prints that I have included have worked. I have also tried to make the code return a variable and define the varable in the if statements, which also does not work.

RANK_ORDER = '34567890JQKA2'
SUIT_ORDER = 'DCHS'
def is_higher(card1, card2):
    card1v = RANK_ORDER.index(card1[0][0])
    card2v = RANK_ORDER.index(card2[0][0])
    card1s = SUIT_ORDER.index(card1[1][:1])
    card2s = SUIT_ORDER.index(card2[1][:1])
    if card1v == card2v:
        if card1s > card2s:
            return True
        else: 
            return False
    elif card1v > card2v:
        return True
    else:
        return False

def sort_cards(cards):
    is_higher(cards[0], cards[1])

if __name__ == '__main__':
    print(sort_cards(['AS', '5H']))

The code doesnt yet sort the cards, but is should say True if the first card is higher. This code prints None.

Answer 1

is_higher returns a value to sort_cards , but you are printing sort_cards return, wich is None, you want to print the return of sort_cards that is the return of the return of is_higher . Just do this:

def sort_cards(cards):
    return is_higher(cards[0], cards[1])