（在Python中）list（string）.reverse（）和list（string）[::-1]有什么区别？

Question

I can execute both expressions in Python shell without error:

string = 'this is a string'
list(string)[::-1]

(output) ['g', 'n', 'i', 'r', 't', 's', ' ', 'a', ' ', 's', 'i', ' ', 's', 'i', 'h', 't']

list(string).reverse()

I can do:

string = ''.join(list(string)[::-1])

which effectively reverse the string in place. However when I do:

string = ''.join(list(string).reverse()

I got an error:

TypeError: can only join an iterable

So list(string).reverse() does not return an iterable but list(string)[::-1] does. Can someone help me understand the underlying differences?

Answer 1

list(string).reverse() modifies the list in place and returns None

So you are are doing:

"".join(None)

Hence the error.

Answer 2

list.reverse()更改了从其调用的列表，因此在调用后会更改列表，而sequence[::-1]创建一个新列表并返回它，因此原始列表不受影响。

Answer 3

list.reverse is returning None so you don't need to assign it back, but, seq[::-1] needs to be assigned back, Example:

l=[1,2,3]
print(l.reverse())
print(l)

Output:

None
[3,2,1]

Example 2:

l=['a','b','c']
print(l[::-1])
print(l)

Output:

['c','b','a']
['a','b','c']

Example 2 needs to be assigned back