Doubt:

Question

In list operations, list1 is same as list2 in first code . Even after list1.append.

But in second code, I appended list1 with different code, then list1 is not same as list2

Why ?I mean in both codes list2 was assigned with list1 value before the modification in list1 attributes

#Code 1
list1 = [1,2,3]
list2 =list1
list1.append(4)

If list1== list2:
print("It's same") #this gets printed

#Code2
list1 = [1,2,3]
list2 = list1
list1 = list1 + [4]
If list1 == list2:
print("it's same") #this is not executed

Answer 1

In a little more detail, the __add__ special method defined for lists returns a new list object when called. This is invoked when using the addition operator on the list. On the other hand, if you do

list1 += [4]

+= should invoke the __iadd__ special method, which instead does in-place addition without returning a new object.

Answer 2

List1=list1+[4] changes the Id of the list.

Answer 3

Thanks for your response , now I am clear :)