Question

Hi I have a question about Quiz 1 #5. Why do you need to insert the two lines at the bottom for the function to meet its specification?

Check out my pastebin:
http://pastebin.com/HJxRKWw0

Answer 1

the problem is that when you set
result = v1
both result and v1 refer to the same address in memory -
if you modify result, you also modify v1, but you are told
not to modify the inputs. to avoid doing this, a copy
of v1 and v2 is made:
v1 = v1[:]
v2 = v2[:]
these are assigned new addresses in memory distinct
from the v1 and v2 in the function call addVectors(v1,v2).
(this would be clearer had he given them new names -
w1 = v1[:] but maybe that's his point...)

Answer 2

Thanks snark exactly what I was looking for.