Python列表sort()函数调用返回None值的问题求助

Hey there! Let's break down why you're seeing None when running that code.

The key thing to know about Python's list.sort() method is that it's an in-place sorting function. That means it modifies the original list directly to put its elements in order, but it doesn't return a new sorted list. When you assign x = cars.sort(), you're assigning the method's return value to x—and since sort() doesn't produce a new list to return, it gives you None instead.

Fixes to get the sorted result you want: #

1. Sort in-place, then print the original list

If you don't need to keep the original unsorted list, just call sort() first, then print the modified cars list:

cars = ['Ford', 'BMW', 'Volvo']
cars.sort()  # This changes the original 'cars' list
print(cars)  # Now prints the sorted list: ['BMW', 'Ford', 'Volvo']

2. Use sorted() to get a new sorted list

If you want to keep the original list intact and store the sorted version in a new variable, use the built-in sorted() function instead. It returns a brand-new sorted list without touching the original:

cars = ['Ford', 'BMW', 'Volvo']
x = sorted(cars)  # sorted() returns a new sorted list
print(x)  # Prints ['BMW', 'Ford', 'Volvo']
print(cars)  # Original list remains unchanged: ['Ford', 'BMW', 'Volvo']

To sum it up: list.sort() mutates the original list and returns None, while sorted() creates and returns a new sorted list. Pick whichever fits your use case!

内容的提问来源于stack exchange，提问作者Sujeet maurya