Extend vs += Behaviour

Question

Help me understand the problem I am failing to identify in the following code.

def extend_a_list(list_var):
    return list_var.extend([6, 2])

def plus_equals_list(list_var):
    list_var += [6]
    return list_var

list_var = [1, 2, 3]
print "Extending"
print extend_a_list(list_var)

list_var = [1, 2, 3]
print "Plus Equals"
print plus_equals_list(list_var)


>>> Extending
>>> None
>>> Plus Equals
>>> [1, 2, 3, 6]

Extend is giving None. Why is that?

Asked By: hlkstuv_23900

||

Source

Answer 1

Extend returns nothing, it modifies the inputted list:

a = [1,2,3]
# a = [1,2,3]
b = a.extend([4])
# a = [1,2,3,4]
# b = None

Answered By: Mathias711

Extend vs += Behaviour

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