Python输出以及为什么

Question

x = [10,20,30]

for i in x:
     print(i)
     x.append(40)
     x = [50,60]

print(x)

Output is :

10
20
30
40
[50,60]

Why is 20, 30, 40 coming? Not 50,60

Answer 1

The reason why this happens is because the loop uses the list object created in line 1. On line 5, you add 40 to this object, and then assign a new object to the x variable . The loop is still using the object you created earlier.

Answer 2

variable i is pointing to old x address. you append 40 in old address once. the new x has different address which i is not pointing to. variable i is still pointing to old x address.

Extra: if you remember when we pass list to function , we pass it by address not as value. this is same concept.