为什么.reverse()不工作？

Question

我试图判断并分割该句子,将其翻转,并将其打印到屏幕上.

我无法理解它是如何.reverse()工作的？当我做的事情:

test = ['This','is','a','test']
new_test = test.reverse()
print(new_test)

当我跑这个我得到None,为什么这个？我怎样才能.reverse()上班？

这是我的最终代码:

sentence = input("What is your sentence? ")
split_sentence = sentence.split().reverse()
for word in sentence:
    print(word,end='')

Answer 1

reverse()在适当的位置运行,并且不返回新阵列.如果要使用副本,则需要执行以下操作:

arr = [1, 2, 3, 4, 5]
copy = arr.copy() # omit this if you don't want a new list
copy.reverse()
# copy now contains [5, 4, 3, 2, 1]
# arr still contains [1, 2, 3, 4, 5]

Answer 2

reverse()在原地反转列表,然后返回None.只需打印原始列表:

test = ['This','is','a','test']
test.reverse() # In-place!
print(test)