Re: How to write this sign function in Delphi.

From	James Kuyper <jameskuyper@verizon.net>
Newsgroups	alt.comp.lang.borland-delphi, alt.comp.lang.c, att.lang.c++, comp.arch, comp.lang.c
Subject	Re: How to write this sign function in Delphi.
Date	2015-09-21 19:15 -0400
Organization	Self
Message-ID	<56008F7B.3030501@verizon.net> (permalink)
References	<1315e$5600499f$d47876e2$34602@news.ziggo.nl> <f3842$5600536b$d47876e2$45003@news.ziggo.nl> <MPG.306a4b87db8f8e87989cf8@news.eternal-september.org> <id210btlsqe47v45golbv08mkesillqbnc@4ax.com>

Cross-posted to 5 groups.

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On 09/21/2015 06:51 PM, Robert Wessel wrote:
> On Mon, 21 Sep 2015 18:15:23 -0400, M Philbrook
> <jamie_ka1lpa@charter.net> wrote:
> 
>> In article <f3842$5600536b$d47876e2$45003@news.ziggo.nl>, skybuck2000
>> @hotmail.com says...
>>>
>>> ! in C is supposed to be logical not.
>>>
>>> Not exactly sure what is ment with that... but to me it would seem this 
>>> converts integers to boolean.
>>>
>>> So this could be some kind of integer to boolean conversion operator.
>>>
>>> Perhaps a typecast to boolean might help for Delphi.
>>>
>>> Anyway I also base this on inspecting the assembly a little bit... there was 
>>> a cmp in it... which probably sets some flags...
>>>
>>> and then some kind of set instruction was executed.
>>>
>>> Just for the kick of it here it is:
>>>
>>>
>>> return ((!!x) | (x >> 31));
...
>>
>> I would like to know why you are using double "!!" ?
>>
>> That is a "not" operation and does nothing more than 
>> give you the reverse.
>>
>> Most likely the compiler is ignoring your bad code.
> 
> 
> !! is a common C idiom for reducing a zero/non-zero value to zero/one.

Which doesn't seem particularly useful as the left operand of a
bitwise-or operator in this context.

My best guess is that he thought it mapped zero/non-zero to zero/(-1).
For certain unportable assumptions about how x>>31 works for negative
numbers, that would produce the right result. That would require that he
have serious misconceptions about how the unary ! operator works - but
the words above make it pretty clear that he's pretty much clueless
about such things.

Thread

How to write this sign function in Delphi. "Skybuck Flying" <skybuck2000@hotmail.com> - 2015-09-21 20:17 +0200
  Re: How to write this sign function in Delphi. "Skybuck Flying" <skybuck2000@hotmail.com> - 2015-09-21 20:43 +0200
  Re: How to write this sign function in Delphi. Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-09-21 19:51 +0100
    Re: How to write this sign function in Delphi. "Skybuck Flying" <skybuck2000@hotmail.com> - 2015-09-21 23:26 +0200
      Re: How to write this sign function in Delphi. Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-09-21 22:47 +0100
        Re: How to write this sign function in Delphi. "Skybuck Flying" <skybuck2000@hotmail.com> - 2015-09-22 16:29 +0200
          Re: How to write this sign function in Delphi. Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-09-22 16:11 +0100
            Re: How to write this sign function in Delphi. "Skybuck Flying" <skybuck2000@hotmail.com> - 2015-09-23 11:18 +0200
              Re: How to write this sign function in Delphi. David Brown <david.brown@hesbynett.no> - 2015-09-23 13:01 +0200
  Re: How to write this sign function in Delphi. "Skybuck Flying" <skybuck2000@hotmail.com> - 2015-09-21 20:53 +0200
  Re: How to write this sign function in Delphi. "Skybuck Flying" <skybuck2000@hotmail.com> - 2015-09-21 20:54 +0200
  Re: How to write this sign function in Delphi. "Skybuck Flying" <skybuck2000@hotmail.com> - 2015-09-21 20:58 +0200
    Re: How to write this sign function in Delphi. M Philbrook <jamie_ka1lpa@charter.net> - 2015-09-21 18:15 -0400
      Re: How to write this sign function in Delphi. supercat@casperkitty.com - 2015-09-21 15:21 -0700
      Re: How to write this sign function in Delphi. Robert Wessel <robertwessel2@yahoo.com> - 2015-09-21 17:51 -0500
        Re: How to write this sign function in Delphi. James Kuyper <jameskuyper@verizon.net> - 2015-09-21 19:15 -0400
          Re: How to write this sign function in Delphi. Robert Wessel <robertwessel2@yahoo.com> - 2015-09-21 23:59 -0500
          Re: How to write this sign function in Delphi. supercat@casperkitty.com - 2015-09-22 09:22 -0700
            Re: How to write this sign function in Delphi. Keith Thompson <kst-u@mib.org> - 2015-09-22 10:32 -0700
            Re: How to write this sign function in Delphi. jt@toerring.de (Jens Thoms Toerring) - 2015-09-22 18:17 +0000
              Re: How to write this sign function in Delphi. supercat@casperkitty.com - 2015-09-22 12:25 -0700
                Re: How to write this sign function in Delphi. jt@toerring.de (Jens Thoms Toerring) - 2015-09-22 22:33 +0000
                Re: How to write this sign function in Delphi. supercat@casperkitty.com - 2015-09-22 15:52 -0700
            Re: How to write this sign function in Delphi. raltbos@xs4all.nl (Richard Bos) - 2015-09-22 23:09 +0000
              Re: How to write this sign function in Delphi. supercat@casperkitty.com - 2015-09-23 09:07 -0700
                Re: How to write this sign function in Delphi. Jorgen Grahn <grahn+nntp@snipabacken.se> - 2015-09-23 16:55 +0000
                Re: How to write this sign function in Delphi. supercat@casperkitty.com - 2015-09-23 10:46 -0700
                Re: How to write this sign function in Delphi. jt@toerring.de (Jens Thoms Toerring) - 2015-09-23 23:18 +0000
                Re: How to write this sign function in Delphi. James Kuyper <jameskuyper@verizon.net> - 2015-09-23 22:29 -0400
                Re: How to write this sign function in Delphi. Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-09-24 11:09 +0100
                Re: How to write this sign function in Delphi. Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-09-27 18:23 -0700
                Re: How to write this sign function in Delphi. glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-09-28 05:20 +0000
                Re: How to write this sign function in Delphi. Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-09-27 23:23 -0700
                Re: How to write this sign function in Delphi. Richard Heathfield <rjh@cpax.org.uk> - 2015-09-28 09:03 +0100
                Re: How to write this sign function in Delphi. Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-09-28 01:24 -0700
                Re: How to write this sign function in Delphi. Richard Heathfield <rjh@cpax.org.uk> - 2015-09-28 09:32 +0100
                Re: How to write this sign function in Delphi. Bartc <bc@freeuk.com> - 2015-09-28 10:22 +0100
                Re: How to write this sign function in Delphi. Richard Heathfield <rjh@cpax.org.uk> - 2015-09-28 11:35 +0100
                Re: How to write this sign function in Delphi. Keith Thompson <kst-u@mib.org> - 2015-09-28 10:33 -0700
                Re: How to write this sign function in Delphi. Richard Heathfield <rjh@cpax.org.uk> - 2015-09-28 18:59 +0100
                Re: How to write this sign function in Delphi. Rosario19 <Ros@invalid.invalid> - 2015-09-28 20:09 +0200
                Re: How to write this sign function in Delphi. Robert Wessel <robertwessel2@yahoo.com> - 2015-09-28 13:39 -0500
                Re: How to write this sign function in Delphi. Richard Heathfield <rjh@cpax.org.uk> - 2015-09-28 20:04 +0100
                Re: How to write this sign function in Delphi. Robert Wessel <robertwessel2@yahoo.com> - 2015-09-28 16:43 -0500
                Re: How to write this sign function in Delphi. Martin Shobe <martin.shobe@yahoo.com> - 2015-09-28 18:55 -0500
                Re: How to write this sign function in Delphi. Robert Wessel <robertwessel2@yahoo.com> - 2015-09-28 19:31 -0500
                Re: How to write this sign function in Delphi. supercat@casperkitty.com - 2015-09-28 12:16 -0700
                Re: How to write this sign function in Delphi. Keith Thompson <kst-u@mib.org> - 2015-09-28 14:31 -0700
                Re: How to write this sign function in Delphi. Robert Wessel <robertwessel2@yahoo.com> - 2015-09-28 16:47 -0500
                Re: How to write this sign function in Delphi. supercat@casperkitty.com - 2015-09-29 11:54 -0700
                Re: How to write this sign function in Delphi. Robert Wessel <robertwessel2@yahoo.com> - 2015-10-01 00:36 -0500
                Re: How to write this sign function in Delphi. raltbos@xs4all.nl (Richard Bos) - 2015-10-02 10:53 +0000
                Re: How to write this sign function in Delphi. supercat@casperkitty.com - 2015-10-02 09:48 -0700
                Re: How to write this sign function in Delphi. Robert Wessel <robertwessel2@yahoo.com> - 2015-10-03 11:27 -0500
                Re: How to write this sign function in Delphi. supercat@casperkitty.com - 2015-10-03 12:32 -0700
                Re: How to write this sign function in Delphi. Robert Wessel <robertwessel2@yahoo.com> - 2015-10-03 11:26 -0500
                Re: How to write this sign function in Delphi. Tim Rentsch <txr@alumni.caltech.edu> - 2015-10-04 16:46 -0700
                Re: How to write this sign function in Delphi. Keith Thompson <kst-u@mib.org> - 2015-09-28 14:23 -0700
                Re: How to write this sign function in Delphi. Robert Wessel <robertwessel2@yahoo.com> - 2015-09-28 16:52 -0500
                Re: How to write this sign function in Delphi. Tim Rentsch <txr@alumni.caltech.edu> - 2015-09-30 01:39 -0700
                Re: How to write this sign function in Delphi. Keith Thompson <kst-u@mib.org> - 2015-09-30 12:37 -0700
                Re: How to write this sign function in Delphi. glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-09-30 21:28 +0000
                Re: How to write this sign function in Delphi. James Kuyper <jameskuyper@verizon.net> - 2015-09-30 17:54 -0400
                Re: How to write this sign function in Delphi. glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-10-01 03:59 +0000
                Re: How to write this sign function in Delphi. James Kuyper <jameskuyper@verizon.net> - 2015-10-01 01:42 -0400
                Re: How to write this sign function in Delphi. Keith Thompson <kst-u@mib.org> - 2015-09-30 16:20 -0700
                Re: How to write this sign function in Delphi. Tim Rentsch <txr@alumni.caltech.edu> - 2015-10-04 16:39 -0700
                Re: How to write this sign function in Delphi. glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-09-28 23:23 +0000
                Re: How to write this sign function in Delphi. supercat@casperkitty.com - 2015-09-29 09:35 -0700
                Re: How to write this sign function in Delphi. raltbos@xs4all.nl (Richard Bos) - 2015-10-02 11:06 +0000
                Re: How to write this sign function in Delphi. supercat@casperkitty.com - 2015-10-02 09:23 -0700
                Re: How to write this sign function in Delphi. Martin Shobe <martin.shobe@yahoo.com> - 2015-10-02 12:07 -0500
                Re: How to write this sign function in Delphi. supercat@casperkitty.com - 2015-10-02 10:47 -0700
                Re: How to write this sign function in Delphi. Keith Thompson <kst-u@mib.org> - 2015-10-02 17:48 -0700
                Re: How to write this sign function in Delphi. Richard Heathfield <rjh@cpax.org.uk> - 2015-10-03 16:46 +0100
                Re: How to write this sign function in Delphi. Martin Shobe <martin.shobe@yahoo.com> - 2015-10-05 10:41 -0500
                Re: How to write this sign function in Delphi. James Kuyper <jameskuyper@verizon.net> - 2015-09-28 15:31 -0400
                Re: How to write this sign function in Delphi. Robert Wessel <robertwessel2@yahoo.com> - 2015-09-28 16:40 -0500
                Re: How to write this sign function in Delphi. James Kuyper <jameskuyper@verizon.net> - 2015-09-28 18:17 -0400
                Re: How to write this sign function in Delphi. Tim Rentsch <txr@alumni.caltech.edu> - 2015-09-30 02:49 -0700
                Re: How to write this sign function in Delphi. supercat@casperkitty.com - 2015-09-30 06:27 -0700
                Re: How to write this sign function in Delphi. Tim Rentsch <txr@alumni.caltech.edu> - 2015-09-29 10:43 -0700
                Re: How to write this sign function in Delphi. glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-09-28 22:51 +0000
                Re: How to write this sign function in Delphi. Tim Rentsch <txr@alumni.caltech.edu> - 2015-09-30 02:11 -0700
                Re: How to write this sign function in Delphi. glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-09-28 22:48 +0000
                Re: How to write this sign function in Delphi. Robert Wessel <robertwessel2@yahoo.com> - 2015-09-28 22:03 -0500
                Re: How to write this sign function in Delphi. Tim Rentsch <txr@alumni.caltech.edu> - 2015-09-30 01:13 -0700
                Re: How to write this sign function in Delphi. Bartc <bc@freeuk.com> - 2015-09-30 17:06 +0100
                Re: How to write this sign function in Delphi. Richard Heathfield <rjh@cpax.org.uk> - 2015-09-30 17:26 +0100
                Re: How to write this sign function in Delphi. Keith Thompson <kst-u@mib.org> - 2015-09-30 13:04 -0700
                Re: How to write this sign function in Delphi. glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-09-28 09:12 +0000
                Re: How to write this sign function in Delphi. David Brown <david.brown@hesbynett.no> - 2015-09-28 12:28 +0200
                Re: How to write this sign function in Delphi. Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-09-28 20:44 +0100
                Re: How to write this sign function in Delphi. Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-10-01 01:39 -0700
                Re: How to write this sign function in Delphi. Keith Thompson <kst-u@mib.org> - 2015-10-01 08:55 -0700
                Re: How to write this sign function in Delphi. supercat@casperkitty.com - 2015-10-01 09:02 -0700
                Re: How to write this sign function in Delphi. Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-10-01 14:55 -0700
                Re: How to write this sign function in Delphi. supercat@casperkitty.com - 2015-10-01 16:48 -0700
                Re: How to write this sign function in Delphi. raltbos@xs4all.nl (Richard Bos) - 2015-10-02 11:46 +0000
                Re: How to write this sign function in Delphi. Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-10-06 00:15 -0700
                Re: How to write this sign function in Delphi. Les Cargill <lcargill99@comcast.com> - 2015-10-06 02:43 -0500
                Re: How to write this sign function in Delphi. David Brown <david.brown@hesbynett.no> - 2015-10-06 10:13 +0200
                Re: How to write this sign function in Delphi. Les Cargill <lcargill99@comcast.com> - 2015-10-06 19:14 -0500
                Re: How to write this sign function in Delphi. supercat@casperkitty.com - 2015-10-06 21:36 -0700
                Re: How to write this sign function in Delphi. Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-10-06 09:25 +0100
                Re: How to write this sign function in Delphi. supercat@casperkitty.com - 2015-10-06 09:28 -0700
                Re: How to write this sign function in Delphi. Keith Thompson <kst-u@mib.org> - 2015-10-06 13:11 -0700
                Re: How to write this sign function in Delphi. supercat@casperkitty.com - 2015-10-06 13:56 -0700
                Re: How to write this sign function in Delphi. glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-10-07 00:25 +0000
                Re: How to write this sign function in Delphi. supercat@casperkitty.com - 2015-10-06 09:44 -0700
                Re: How to write this sign function in Delphi. Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-10-06 10:08 -0700
                Re: How to write this sign function in Delphi. supercat@casperkitty.com - 2015-10-06 12:00 -0700
                Re: How to write this sign function in Delphi. Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-10-07 01:58 -0700
                Re: How to write this sign function in Delphi. Richard Heathfield <rjh@cpax.org.uk> - 2015-10-07 10:12 +0100
                Re: How to write this sign function in Delphi. supercat@casperkitty.com - 2015-10-08 00:40 -0700
                Re: How to write this sign function in Delphi. Philip Lantz <prl@canterey.us> - 2015-10-03 12:29 -0700
                Re: How to write this sign function in Delphi. supercat@casperkitty.com - 2015-10-03 13:20 -0700
                Re: How to write this sign function in Delphi. Philip Lantz <prl@canterey.us> - 2015-10-03 12:33 -0700
                Re: How to write this sign function in Delphi. James Kuyper <jameskuyper@verizon.net> - 2015-10-03 17:02 -0400
                Re: How to write this sign function in Delphi. supercat@casperkitty.com - 2015-10-03 15:04 -0700
                Re: How to write this sign function in Delphi. glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-10-04 05:12 +0000
                Re: How to write this sign function in Delphi. supercat@casperkitty.com - 2015-10-04 12:58 -0700
                Re: How to write this sign function in Delphi. Philip Lantz <prl@canterey.us> - 2015-10-03 12:37 -0700
                Re: How to write this sign function in Delphi. James Kuyper <jameskuyper@verizon.net> - 2015-10-03 16:21 -0400
                Re: How to write this sign function in Delphi. supercat@casperkitty.com - 2015-10-03 16:05 -0700
                Re: How to write this sign function in Delphi. supercat@casperkitty.com - 2015-10-03 14:02 -0700
                Re: How to write this sign function in Delphi. supercat@casperkitty.com - 2015-09-24 09:39 -0700
                Re: How to write this sign function in Delphi. raltbos@xs4all.nl (Richard Bos) - 2015-09-27 16:26 +0000
        Re: How to write this sign function in Delphi. M Philbrook <jamie_ka1lpa@charter.net> - 2015-09-21 22:06 -0400
          Re: How to write this sign function in Delphi. James Kuyper <jameskuyper@verizon.net> - 2015-09-22 10:17 -0400
            Re: How to write this sign function in Delphi. M Philbrook <jamie_ka1lpa@charter.net> - 2015-09-22 19:48 -0400
              Re: How to write this sign function in Delphi. Noob <root@127.0.0.1> - 2015-09-23 13:15 +0200
  Re: How to write this sign function in Delphi. "Skybuck Flying" <skybuck2000@hotmail.com> - 2015-09-21 21:25 +0200
    Re: How to write this sign function in Delphi. "Skybuck Flying" <skybuck2000@hotmail.com> - 2015-09-21 21:54 +0200
    Re: How to write this sign function in Delphi. "Skybuck Flying" <skybuck2000@hotmail.com> - 2015-09-21 22:02 +0200
  Re: How to write this sign function in Delphi. "Skybuck Flying" <skybuck2000@hotmail.com> - 2015-09-21 21:50 +0200
  Re: How to write this sign function in Delphi. M Philbrook <jamie_ka1lpa@charter.net> - 2015-09-21 18:08 -0400
    Re: How to write this sign function in Delphi. "Skybuck Flying" <skybuck2000@hotmail.com> - 2015-09-22 08:31 +0200
  Re: How to write this sign function in Delphi. "Skybuck Flying" <skybuck2000@hotmail.com> - 2015-09-22 10:18 +0200
  Re: How to write this sign function in Delphi. "Skybuck Flying" <skybuck2000@hotmail.com> - 2015-09-22 10:50 +0200
    Re: How to write this sign function in Delphi. "Skybuck Flying" <skybuck2000@hotmail.com> - 2015-09-22 11:00 +0200
    Re: How to write this sign function in Delphi. "Skybuck Flying" <skybuck2000@hotmail.com> - 2015-09-22 11:07 +0200
    Re: How to write this sign function in Delphi. "Skybuck Flying" <skybuck2000@hotmail.com> - 2015-09-22 11:20 +0200
  Re: How to write this sign function in Delphi. "Skybuck Flying" <skybuck2000@hotmail.com> - 2015-09-22 11:15 +0200
    Re: How to write this sign function in Delphi. "Skybuck Flying" <skybuck2000@hotmail.com> - 2015-09-22 11:23 +0200

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