I know the output, but I still do not understand why this is the output.

Question

Could anybody please explain this?

def func(x):
res = 0
for i in range(x):
res += i
return res

print(func(4))

Answer 1

range (4) expands to the list 0, 1, 2, 3

i = 0
res = 0 + 0 = 0
i = 1
res = 0 + 1 = 1
i = 2
res = 1 + 2 = 3
i = 3
res = 3 + 3 = 6

Does that help?

Answer 2

Actually with the in range syntax you create an array. So your statement could have been as follows:
var x[4]. instead

Answer 3

Oh my god, I suddenly see it!
Thank you so much :-)

Answer 4

It says the answer is 6.
I do not see how to get to 6...