Question

请向我解释此代码。这是一个将整数输入打印为字母输出的程序。如果我输入35，则输出将为35。我了解其中的大部分内容，但想知道数十如何从

中获取价值

twenty thirty forty fifty sixty seventy eighty ninety

代码是：

num = int(input("Enter the number:"))
numbers = ("zero one two three four five six seven eight nine".split())
numbers.extend("ten eleven twelve thirteen fourteen fifteen sixteen".split())
numbers.extend("seventeen eighteen nineteen".split())
numbers.extend(tens if ones == "zero" else (tens + " " + ones) 
    for tens in "twenty thirty forty fifty sixty seventy eighty ninety".split()
    for ones in numbers[0:10])

print(numbers[num])

Answer 1

在最后一行看到的两个主要概念是list comprehension和nested loops。看看。

为了更好地了解发生了什么，我们将在较简单的部分中拆分该行：

TENS

for tens in "twenty thirty forty fifty sixty seventy eighty ninety".split():
    print(tens)

输出：二十三四十五六十七八百八十九十

上一个for循环在列表理解中与此相对应：

(tens for tens in "twenty thirty forty fifty sixty seventy eighty ninety".split())

不带print的返回生成器。如果要查看结果：

print(list(tens for tens in "twenty thirty forty fifty sixty seventy eighty ninety".split()))

一个

numbers = ("zero one two three four five six seven eight nine".split())
for ones in numbers[0:10]:
    print(ones)

输出：零一二三四有五六七七八九

上一个for循环在列表理解中与此相对应：

    (ones for ones in numbers[0:10])

合并循环

我们可以合并它们：

for tens in "twenty thirty forty fifty sixty seventy eighty ninety".split():
    for ones in numbers[0:10]:
        print(tens + " " + ones)
OUTPUT: twenty zero
twenty one
twenty two
twenty three
twenty four
twenty five
twenty six
twenty seven
twenty eight
twenty nine
thirty zero
thirty one
thirty two
[...]

由于我们不太喜欢twenty zero，因此我们将添加一个子句：

for tens in "twenty thirty forty fifty sixty seventy eighty ninety".split():
    for ones in numbers[0:10]:
        if ones == "zero":
            print(tens)
        else:
            print(tens + " " + ones)
OUTPUT:
twenty
twenty one
twenty two
twenty three
twenty four
[...]

这与列表理解是相同的行为：

(tens if ones == "zero" else (tens + " " + ones) for tens in "twenty thirty forty fifty sixty seventy eighty ninety".split() for ones in numbers[0:10])

返回列表（* generator），该列表将扩展到您的numbers列表。
最后，您输入的数字对应于列表中单词的索引

嵌套for循环扩展现有列表

1 个答案: