From: Robert Klemme <bob.news@...>
Date: 2004-09-23T17:44:50+09:00
Subject: Re: negative numbers and binary formats


"Florian Gross" <flgr@ccan.de> schrieb im Newsbeitrag
news:2rduavF18hbhuU1@uni-berlin.de...
> Paul wrote:
>
> Moin!
>
> > Im trying to take a negative integer value, convert it to its binary
> > equivalent, and save its hex value
> >
> > -7 -> 1111 1001 -> F9
>
> Does this help?
>
> irb(main):032:0> [-7].pack("c").unpack("H*").first
> => "f9"

That's nice although it is somewhat limited regarding the size of values:

>> [-7000].pack("c").unpack("H*").first
=> "a8"

After a bit experimenting I came up with this:

>> [-7].pack("i").unpack("h*").shift.reverse.gsub(/^f+(?=f)/, '')
=> "f9"
>> [-7000000].pack("i").unpack("h*").shift.reverse.gsub(/^f+(?=f)/, '')
=> "f953040"

Florian, what do you think?

Kind regards

    robert