为什么它不直接给出列表本身？

Question

我有这个功能

def calc_score(player):
    """Calculates the score of the specified player (player)"""
    score = 0
    if player == "user":
        for card in range(0, len(user_cards)):
            score += user_cards[int(card)]
    elif player == "comp":
        for card in range(0, len(comp_cards)):
            score += comp_cards[int(card)]
    else:
        return
    return score

当它被调用时，它给了我这个错误：

line 27, in calc_score
    score += user_cards[int(card)]
TypeError: unsupported operand type(s) for +=: 'int' and 'list'

我在thonny中调试了它，结果发现它说

['placeholder1', 'placeholder2'][0]

只是给出了列表本身。

我什至用看似等效的代码对其进行了测试，并且它有效。

user_cards = [11,10]
comp_cards = [10,8]

score = 0
if "user" == "user":
    for card in range(0, len(user_cards)):
        score += user_cards[int(card)]
elif "user" == "comp":
    for card in range(0, len(comp_cards)):
        score += comp_cards[int(card)]
else:
    print()
print(score)

输出：21

我检查了变量和列表的值，它们也正常。

我没发现什么问题。

最后这是整个脚本（截至发布此答案）：

import random

# Define Variables

cards = [11, 2, 3, 4, 5, 6, 7, 8, 9, 10, 10, 10, 10]
user_cards = []
comp_cards = []
user_score = 0
comp_score = 0

# Define Functions

def give_card(num):
    """Returns random cards of a certain amount (num)"""
    num = int(num)
    cards_give = []
    for card in range(0, num):
        cards_give.append(random.choice(cards))
    return cards_give


def calc_score(player):
    """Calculates the score of the specified player (player)"""
    score = 0
    if player == "user":
        for card in range(0, len(user_cards)):
            score += user_cards[int(card)]
    elif player == "comp":
        for card in range(0, len(comp_cards)):
            score += comp_cards[int(card)]
    else:
        return
    return score

user_cards.append(give_card(2))
comp_cards.append(give_card(2))
user_score = calc_score("user")
comp_score = calc_score("comp")

Answer 1

您的问题在这里：

user_cards.append(give_card(2))

user_cards

是一个列表，

give_card(2)

返回另一个包含两个数字的列表。将列表附加到列表使附加列表本身成为结果列表的元素：

list = [1, 2]
list.append([3,4])
print(list) # prints [1, 2, [3, 4]]

你需要的是

user_cards += give_card(2)