[REBOL] Re: for bug?
From: joel:neely:fedex at: 16-Jun-2002 16:42
Hi, Romano,
It has to do with (non-intuitive IMHO) handling of arithmetic
on character values...
Romano Paolo Tenca wrote:
> In a console
>
> for x #"^(00)" #"^(ff)" 1 [print to integer! x]
>
> -> endless loop
>
No matter how many times you add 1 to a character value, it
will never be greater than #"^(ff)" (believe it or not!)
>> foo: #"^(ff)"
== #"ÿ"
>> foo + 1
== #"^@"
>> to-integer foo + 1
== 0
You might have been expecting that
>> (to-integer foo) + 1
== 256
would cause the loop to exit once the counter had exceeded
the stated upper bound, but...
>> to-char (to-integer foo) + 1
** Math Error: Math or number overflow
** Where: to-char
** Near: to char! :value
On the other hand,
for x to-integer #"^(00)" to-integer #"^(ff)" 1 [print x]
works just fine, and you can use the phrase
to-char x
inside the body of the FOR if you really wanted to do something
with all possible character values.
-jn-
--
; Joel Neely joeldotneelyatfedexdotcom
REBOL [] do [ do func [s] [ foreach [a b] s [prin b] ] sort/skip
do function [s] [t] [ t: "" foreach [a b] s [repend t [b a]] t ] {
| e s m!zauafBpcvekexEohthjJakwLrngohOqrlryRnsctdtiub} 2 ]
