Re: how cast works?

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From	Keith Thompson <Keith.S.Thompson+u@gmail.com>
Newsgroups	comp.lang.c
Subject	Re: how cast works?
Date	Thu, 08 Aug 2024 12:39:14 -0700
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Thiago Adams <thiago.adams@gmail.com> writes:
> On 07/08/2024 17:08, Keith Thompson wrote:
>> Thiago Adams <thiago.adams@gmail.com> writes:
>>> How cast works?
>>> Does it changes the memory?
>>> For instance, from "unsigned int" to "signed char".
>>> Is it just like discarding bytes or something else?
>
> I also curious about how bool works.
>
> Values converted to bool became 0 or 1.
> When this conversion happens, at read or write? Both?

I don't know what you mean by that.

A conversion takes a value of some type and yields a value of some
(other) type.  If the target type is bool, the result is false (0) if
the operand is equal to zero, true (1) otherwise.

A cast is simply an explicit conversion.  Explict and implicit
conversions do the same thing.  (Some conversions can only be done
explicitly.)

A converted value does not "become" 0 or 1; the conversion *yields*
0 or 1.  The value of (bool)42 is 1, but 42 is still 42.

> How much does it cost?

It depends on what code the compiler generates; the language doesn't
address that.  It could be free if the result isn't used and the
compiler optimizes it away.

[...]

-- 
Keith Thompson (The_Other_Keith) Keith.S.Thompson+u@gmail.com
void Void(void) { Void(); } /* The recursive call of the void */

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how cast works? Thiago Adams <thiago.adams@gmail.com> - 2024-08-07 08:28 -0300
  Re: how cast works? Thiago Adams <thiago.adams@gmail.com> - 2024-08-07 08:33 -0300
    Re: how cast works? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-07 13:13 -0700
    Re: how cast works? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-08-11 17:43 -0700
      Re: how cast works? Vir Campestris <vir.campestris@invalid.invalid> - 2024-08-12 11:51 +0100
        Challenge/exercise problem - signum() function Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-08-12 08:17 -0700
          Re: Challenge/exercise problem - signum() function Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2024-08-12 16:07 +0000
            Re: Challenge/exercise problem - signum() function Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-08-12 09:57 -0700
  Re: how cast works? Dan Purgert <dan@djph.net> - 2024-08-07 20:00 +0000
    Re: how cast works? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-07 13:26 -0700
    Re: how cast works? Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-08-07 23:00 +0000
    Re: how cast works? Thiago Adams <thiago.adams@gmail.com> - 2024-08-08 08:14 -0300
      Re: how cast works? Bart <bc@freeuk.com> - 2024-08-08 14:23 +0100
        Re: how cast works? Michael S <already5chosen@yahoo.com> - 2024-08-08 19:32 +0300
          Re: how cast works? Thiago Adams <thiago.adams@gmail.com> - 2024-08-08 14:11 -0300
          Re: how cast works? Bart <bc@freeuk.com> - 2024-08-08 18:29 +0100
            Re: how cast works? Thiago Adams <thiago.adams@gmail.com> - 2024-08-08 14:50 -0300
              Re: how cast works? Thiago Adams <thiago.adams@gmail.com> - 2024-08-08 14:57 -0300
              Re: how cast works? Bart <bc@freeuk.com> - 2024-08-08 19:01 +0100
                Re: how cast works? Thiago Adams <thiago.adams@gmail.com> - 2024-08-08 15:13 -0300
              Re: how cast works? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-08 12:29 -0700
            Re: how cast works? David Brown <david.brown@hesbynett.no> - 2024-08-08 19:58 +0200
              Re: how cast works? Bart <bc@freeuk.com> - 2024-08-08 20:09 +0100
                Re: how cast works? David Brown <david.brown@hesbynett.no> - 2024-08-09 00:32 +0200
                Re: how cast works? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-08 16:14 -0700
                Re: how cast works? Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-08-09 02:47 +0000
                Re: how cast works? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-08 22:55 -0700
                Re: how cast works? James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-08-09 02:08 -0400
                Re: how cast works? David Brown <david.brown@hesbynett.no> - 2024-08-09 18:16 +0200
                Re: how cast works? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-09 12:18 -0700
                Re: how cast works? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-08-11 17:07 -0700
                Re: how cast works? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-11 20:14 -0700
                Re: how cast works? Bart <bc@freeuk.com> - 2024-08-09 01:56 +0100
                Re: how cast works? David Brown <david.brown@hesbynett.no> - 2024-08-09 19:08 +0200
                Re: how cast works? Bart <bc@freeuk.com> - 2024-08-10 11:03 +0100
                Re: how cast works? Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-08-09 02:45 +0000
      Re: how cast works? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-08 12:42 -0700
        Re: how cast works? Thiago Adams <thiago.adams@gmail.com> - 2024-08-08 17:34 -0300
          Re: how cast works? Bart <bc@freeuk.com> - 2024-08-08 22:41 +0100
            Re: how cast works? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-08 16:17 -0700
              Re: how cast works? Bart <bc@freeuk.com> - 2024-08-09 11:04 +0100
                Re: how cast works? David Brown <david.brown@hesbynett.no> - 2024-08-09 19:12 +0200
                Re: how cast works? Bart <bc@freeuk.com> - 2024-08-12 15:36 +0100
                Re: how cast works? James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-08-09 13:57 -0400
                Re: how cast works? Bart <bc@freeuk.com> - 2024-08-09 21:59 +0100
                Re: how cast works? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-09 14:47 -0700
                Re: how cast works? Bart <bc@freeuk.com> - 2024-08-10 00:32 +0100
                Re: how cast works? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-09 17:12 -0700
                Re: how cast works? James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-08-09 18:29 -0400
                Re: how cast works? David Brown <david.brown@hesbynett.no> - 2024-08-13 11:18 +0200
                Re: how cast works? Bart <bc@freeuk.com> - 2024-08-13 11:34 +0100
                Re: how cast works? James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-08-13 07:51 -0400
                Re: how cast works? Bart <bc@freeuk.com> - 2024-08-13 14:01 +0100
                Re: how cast works? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-13 12:46 -0700
                Re: how cast works? Bart <bc@freeuk.com> - 2024-08-13 21:51 +0100
                Re: how cast works? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-08-13 16:46 -0700
                Re: how cast works? Bart <bc@freeuk.com> - 2024-08-14 00:56 +0100
                Re: how cast works? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-08-18 03:37 -0700
                Re: how cast works? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-09 14:29 -0700
                Re: how cast works? James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-08-09 18:35 -0400
                Re: how cast works? Kaz Kylheku <643-408-1753@kylheku.com> - 2024-08-09 21:30 +0000
                Re: how cast works? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-09 14:57 -0700
                Re: how cast works? Kaz Kylheku <643-408-1753@kylheku.com> - 2024-08-09 23:14 +0000
                Re: how cast works? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-09 16:58 -0700
                Re: how cast works? Kaz Kylheku <643-408-1753@kylheku.com> - 2024-08-10 00:06 +0000
                Re: how cast works? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-09 17:27 -0700
                Re: how cast works? James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-08-09 20:31 -0400
                Re: how cast works? Bart <bc@freeuk.com> - 2024-08-10 01:11 +0100
                Re: how cast works? David Brown <david.brown@hesbynett.no> - 2024-08-13 11:23 +0200
                Re: how cast works? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-08-11 17:32 -0700
                Re: how cast works? James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-08-09 18:35 -0400
                Re: how cast works? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-08-11 17:27 -0700
                Re: how cast works? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-09 12:23 -0700
                Re: how cast works? Bart <bc@freeuk.com> - 2024-08-09 21:31 +0100
                Re: how cast works? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-09 13:49 -0700
                Re: how cast works? Bart <bc@freeuk.com> - 2024-08-09 22:01 +0100
                Re: how cast works? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-08-12 00:33 -0700
                Re: how cast works? Bart <bc@freeuk.com> - 2024-08-12 12:21 +0100
              Re: how cast works? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-08-11 17:46 -0700
                Re: how cast works? Bart <bc@freeuk.com> - 2024-08-12 02:00 +0100
                Re: how cast works? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-11 20:23 -0700
                Re: how cast works? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-08-11 20:37 -0700
                Re: how cast works? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-11 21:33 -0700
                Re: how cast works? Ben Bacarisse <ben@bsb.me.uk> - 2024-08-12 16:57 +0100
                Re: how cast works? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-08-12 10:04 -0700
                Re: how cast works? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-12 13:35 -0700
            Re: how cast works? Thiago Adams <thiago.adams@gmail.com> - 2024-08-09 07:57 -0300
              Re: how cast works? Bart <bc@freeuk.com> - 2024-08-09 16:25 +0100
                Re: how cast works? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-09 12:06 -0700
              Re: how cast works? David Brown <david.brown@hesbynett.no> - 2024-08-09 19:20 +0200
                Re: how cast works? Thiago Adams <thiago.adams@gmail.com> - 2024-08-09 15:54 -0300
                Re: how cast works? Thiago Adams <thiago.adams@gmail.com> - 2024-08-09 16:05 -0300
                Re: how cast works? David Brown <david.brown@hesbynett.no> - 2024-08-09 21:43 +0200
                Re: how cast works? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-09 13:28 -0700
                Re: how cast works? David Brown <david.brown@hesbynett.no> - 2024-08-09 22:01 +0200
                Re: how cast works? Bart <bc@freeuk.com> - 2024-08-10 11:17 +0100
                Re: how cast works? Thiago Adams <thiago.adams@gmail.com> - 2024-08-10 10:15 -0300
                Re: how cast works? Bart <bc@freeuk.com> - 2024-08-10 17:14 +0100
                Re: how cast works? Thiago Adams <thiago.adams@gmail.com> - 2024-08-10 20:01 -0300
                Re: how cast works? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-10 17:10 -0700
                Re: how cast works? Thiago Adams <thiago.adams@gmail.com> - 2024-08-11 09:23 -0300
                Re: how cast works? Bart <bc@freeuk.com> - 2024-08-11 13:30 +0100
                Re: how cast works? Thiago Adams <thiago.adams@gmail.com> - 2024-08-11 14:16 -0300
                Re: how cast works? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-11 13:38 -0700
                Re: how cast works? Bart <bc@freeuk.com> - 2024-08-12 12:24 +0100
                Re: how cast works? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-09 13:26 -0700
                Re: how cast works? Thiago Adams <thiago.adams@gmail.com> - 2024-08-09 18:01 -0300
                Re: how cast works? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-09 14:53 -0700
              Re: how cast works? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-09 12:03 -0700
                Re: how cast works? Thiago Adams <thiago.adams@gmail.com> - 2024-08-09 16:22 -0300
          Re: how cast works? David Brown <david.brown@hesbynett.no> - 2024-08-09 00:36 +0200
    Re: how cast works? Dan Purgert <dan@djph.net> - 2024-08-08 14:08 +0000
    Re: how cast works? Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-08-09 02:42 +0000
  Re: how cast works? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-07 13:08 -0700
    Re: how cast works? Thiago Adams <thiago.adams@gmail.com> - 2024-08-08 08:35 -0300
      Re: how cast works? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-08 12:39 -0700
      Re: how cast works? James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-08-08 18:40 -0400
        Re: how cast works? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-08-11 17:15 -0700
    Is there an audio book version (Was: how cast works?) gazelle@shell.xmission.com (Kenny McCormack) - 2024-08-08 16:19 +0000
  Re: how cast works? Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-08-07 23:03 +0000

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