是否应为内置Python函数sort（）导入库

Question

我有以下用Python 2.7编写的程序

numbers = [25, 03, 91, 59, 10, 12, 6, 9]
print(numbers)
print (numbers.sort())

输出结果为：

[25, 3, 91, 59, 10, 12, 6, 9]
None

为什么返回无？

Answer 1

它正在返回None，因为sort()会更改列表，但不会返回新列表：

>>>> numbers = [25, 03, 91, 59, 10, 12, 6, 9]
>>>> print(numbers)
[25, 3, 91, 59, 10, 12, 6, 9]
>>>> numbers.sort()
>>>> print(numbers)
[3, 6, 9, 10, 12, 25, 59, 91]

Answer 2

Python的sort()对列表进行排序并返回None。如果要打印已排序的列表，只需再次打印列表。

numbers = [1,4,2,3,5]
print(numbers)  # prints [1,4,2,3,5]
numbers.sort()
print(numbers)  # prints [1,2,3,4,5]

此外，Python有一个内置sorted()，它返回列表的副本，已排序。

numbers = [1,4,2,3,5]
print(numbers)          # prints [1,4,2,3,5]
print(sorted(numbers))  # prints [1,2,3,4,5]