Bubble Sorting List Sorting Returns None In Python

Question

I am trying to learn how the bubble sorting algorithm works in python. However sorting the list returns None when i print out the output.

Here Is My Code

arr = ["A", "B", "C", "D", "Z", "Y"]


def _sort(nums):
    for i in range(len(nums)-1, 0, -1):
        for j in range(i):
            if nums[j] > nums[j+1]:
                temp = nums[j+1]
                nums[j+1] = temp

    
_sorted = _sort(arr)
print(_sorted)

Here Is Output When I Print Out The Result.

None

Answer 1

First, the algorithm is not right. You should do something like this:

def _sort(nums):
    for i in range(len(nums)-1, 0, -1):
        for j in range(i):
            if nums[j] > nums[i]:
                temp = nums[i]
                nums[i] = nums[j]
                nums[j] = temp

Second, the function does not return anything. That is why it returns None. However, the list arr is now sorted. You can check it by running this code:

arr = ["A", "B", "C", "D", "Z", "Y"]


def _sort(nums):
    for i in range(len(nums)-1, 0, -1):
        for j in range(i):
            if nums[j] > nums[i]:
                temp = nums[i]
                nums[i] = nums[j]
                nums[j] = temp
                

_sort(arr)  # This function does not return anything
print(arr)