Reversing a list with single element gives None

Question

I noticed odd behaviour when returning a list (with a single element) from a function and then trying to reverse it, using reverse()

I’ve distilled it here:

def myFunction():
  return ["The Smiths"]

nums = [5,4,3,2,1]
nums.reverse()
print nums # 1,2,3,4,5 - fine!

# lets use one element in a list
something = ["Gwen Stefani"]
something.reverse()
print something # ["Gwen Stefani"] also fine

# now let's do the same, but from a function
a = myFunction()
print a # The Smiths
print a.reverse() # None
print a[::-1] # The Smiths

I need a grown-up to explain what is going on to create the None instead of the single element as seen with [::-1].

Asked By: Ghoul Fool

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Source

Answer 1

list.reverse() reverses the list in-place, but the function itself doesn’t return anything.

a = ["The Smiths"]
print a # The Smiths
print a.reverse() # None
print a # It's already there

Answered By: iBug

Reversing a list with single element gives None

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