High limit on gen_range is never returned

[mightypenguin]

Going through the "guess_number" rust program example and using this line:

let secret_number = rand::thread_rng().gen_range(0, 1);

secret_number will never have a value of 1 (at least not during repeated testing)
Also true for slightly larger range like (0, 5) that the high limit is not returned.

It's probably ok if the high limit is never returned, but the documentation should indicate that the high limit is not inclusive (while the low limit IS inclusive). I think it's closer to user expectations to make them both inclusive. The current behavior does appear to coincide with Python's but is non-intuitive.

Rust 1.19.0
RHEL7 in a VM

[burdges]

Rust's ranges exclude the right hand bound normally. You must ask for an inclusive range explicitly : https://doc.rust-lang.org/std/ops/struct.RangeInclusive.html.

[pitdicker]

I think this can be closed, as this is the intended behaviour and changing gen_range is a very subtle breaking change.

Note that when the rand crate revision lands it is possible to get inclusive ranges with distributions::Range::new_inclusive.

[dhardy]

Ok, I'll leave this open as a reminder to check the documentation on gen_range. I'll be making a fairly big PR affecting this in the next few days.