Why does sorting a list return None?

Question

My code is written in python 3 and it is meant to print out palindromes.
It should iterate through all the palindromic products of 2 3-digit numbers as shown below:

mylist=[]
for i in range(999,99,-1):
    for x in range(999, i-1, -1,):
        number=i*x
        number=str(number)
        if number==number[::-1]:
            #print(number)         
            mylist.append(number)
mylist=mylist.sort(reverse=True)
print(mylist)

Note the commented out print. When this was still in place, all the palindromes that should have been printed out came out.
When I run my code, without the print statement, the console only prints out ‘None’.

As far as I can see my logic is in order, so why is this happening?
EDIT:
Also, when I sort my list in reverse order, 99999 comes first. I gather this is because python looks at the consecutive 9’s and thinks it is the biggest.
However, is there an easy way to get the actual biggest number?

Asked By: S.L

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Source

Answer 1

list.sort() always returns None (the list is sorted in-place). What you want is sorted(list) which returns a new sorted list.

Then you can sort them like this:

mylist = [int(x) for x in mylist]
mylist.sort(reverse=True)
mylist = [str(x) for x in mylist]

Answered By: JulienD

Why does sorting a list return None?

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