Question

for i in list:
    j = i + 1
    print i - j

This will print out -1 times the length of list

What I wanted to do is to print the difference between value i and the next in the list.

Am I clear?

Answer 1

for i in list:

binds i to the elements of list, not its indexes. You might have meant

for i in xrange(len(list)):

or

for i, _ in enumerate(list):

Then get the element at index i with list[i].

(And please don’t call a list list; that’s the name of a Python built-in function.)