Appending a value in variable changes both values

Question

Look at the code:

a = ['Hello']
b = a          # ['Hello']

b.append(2)
print b        # ['Hello', 2]
print a        # ['Hello', 2]

Here, a is assigned to b, meaning that the change of value in a can affect the value of b. How can the change in b can affect a in this case?

Is it that List in python have any special rule where appending a value can affect both a and b?

Please go through https://stackoverflow.com/questions/8056130/immutable-vs-mutable-types — itzMEonTV, Oct 25 '17 at 06:43
No, **all python objects work this way**. please read Ned Batchelder's [Facts and Myths about python names and values](https://nedbatchelder.com/text/names.html) — juanpa.arrivillaga, Oct 25 '17 at 06:43
The link you sent has good explanations, but the thing I asked was reverse than the 5th Fact mentioned i.e. (Fact: Assignment never copies data.) @juanpa.arrivillaga — Jay, Oct 25 '17 at 06:58

score 0 · Answer 1 · answered Oct 25 '17 at 06:43

0

Because it's exactly the same value. Names are bound to references, which means that b = a points both to the same list.

answered Oct 25 '17 at 06:43

1 Answers1