What is the return value of the range() function in python?

Question

I thought that the range() function returns a list with the arguments that you have put inside the parentheses. But when I type range(4) in IDLE, I get range(0, 4) as output. Similarly, when I type print(range(4)), I also get range(0, 4) as output. I am currently using python 3.5.

I am currently studying python with the following eBook: "How To Think Like a Computer Scientist" and in that eBook, they provide active code blocks where you can run python code. And when I run print(range(4)) in there, I do get the list that I expected, i.e. [0, 1, 2, 3].

Can someone explain this to me?

Thanks in advance!

Answer 1

print(range(10)) returns range(0, 10) as output

In many ways the object returned by range() behaves as if it is a list, but in fact it isn’t. It is an object which returns the successive items of the desired sequence when you iterate over it, but it doesn’t really make the list, thus saving space.

We say such an object is iterable, that is, suitable as a target for functions and constructs that expect something from which they can obtain successive items until the supply is exhausted. We have seen that the for statement is such an iterator. The function list() is another; it creates lists from iterables:

list(range(5)) returns [0, 1, 2, 3, 4] as output