Mailing List Archive: 49091 messages

## [REBOL] Re: cycling

### From: joel:neely:fedex at: 6-Jul-2001 13:33

```
Jeff Kreis wrote:
> > Given a set of M "index" values, what's the simplest way to
> > cycle through them, both forward and backward?
>
> "A set of M 'index' values" -- you mean a block?
>

No, I was referring to manipulating the value of a counter.

Given a variable set to an integer within a restricted range of M
values (either 0 .. M-1 or 1 .. M), what is the simplest way to
step that variable to the next or previous value within the range,
with "wrap-around" at either end of the range.

If the range is 0 .. 4, then successive steps forward from 3 would
produce 4, 0, 1, 2, 3, 4, 0, 1, 2, ...

If the range is 1 .. 5, then successive steps backward from 3 would
produce 3, 2, 1, 5, 4, 3, 2, 1, 5, 4, ...

Hope that's clearer.

-jn-
___________________________________________________________________
The purpose of computing is insight, not numbers!
- R. W. Hamming

joel'dot'neely'at'fedex'dot'com
```