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Groups > comp.lang.c > #383790

Re: filling area by color atack safety

From Tim Rentsch <tr.17687@z991.linuxsc.com>
Newsgroups comp.lang.c
Subject Re: filling area by color atack safety
Date 2024-03-20 07:52 -0700
Organization A noiseless patient Spider
Message-ID <864jd1lzvn.fsf@linuxsc.com> (permalink)
References (2 earlier) <865xxiok09.fsf@linuxsc.com> <20240319131842.00002138@yahoo.com> <86o7b9ms7d.fsf@linuxsc.com> <20240320115416.00001ab5@yahoo.com> <87jzlxi4lq.fsf@bsb.me.uk>

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Ben Bacarisse <ben.usenet@bsb.me.uk> writes:

> Michael S <already5chosen@yahoo.com> writes:
>
>> On Tue, 19 Mar 2024 21:40:22 -0700
>> Tim Rentsch <tr.17687@z991.linuxsc.com> wrote:
>>
>>> Michael S <already5chosen@yahoo.com> writes:
>
> ...
>
>>>>> Tim Rentsch <tr.17687@z991.linuxsc.com> writes:
>
> ...
>
>>>>> static  _Bool  change_it( UI w, UI h, Color [w][h], Point, Color,
>>>>> Color );
>>>>
>>>> Besides, I don't think that use of VLA in library code is a
>>>> good idea.  VLA is optional in latest C standards.  And
>>>> incompatible with C++.
>>>
>>> The code uses a variably modified type, not a variable length
>>> array.
>>
>> I am not sufficiently versed in C Standard terminology to see a
>> difference.
>
> A VLA is a declared object -- an array with a size that is not a
> compile-time constant.  A variably modified type is just a type,
> not an object.  Obviously one can use such a type to declare a
> VLA, but when it is the type of a function parameter, there need
> be no declared object with that type.  Usually the associated
> function argument will have been dynamically allocated.

Also ordinary local variables can be declared to have a variably
modified type (the type not necessarily having been introduced
separately), often a benefit for code that is dealing with
multi-dimensional arrays.

>> Aren't they both introduced in C99 and made optional in later
>> standards?
>
> I think so but that's a shame since VMTs are very helpful for
> writing array code.  They avoid the need to keep calculating the
> index with multiplications.

C11 added a pre-defined preprocessor macro __STDC_NO_VLA__, which
implementations can define to be 1 "intended to indicate that the
implementation does not support variable length arrays or variably
modified types."  It's amusing to note that an implementation can
support VLAs and VMTs but still define the macro if they are not
intended to be supported. ;)

> Making both optional was a classic case of throwing the baby out
> with the bath water.  Few of the objections raised about VLAs
> apply to VMTs.

Agree 100%.

Someone who wants to take a stand on this issue might to consider
adding the following lines

    #if  __STDC_NO_VLA__
    #error Substandard implementation detected
    #endif

at various places around their source code.

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Thread

filling area by color atack safety fir <fir@grunge.pl> - 2024-03-16 05:11 +0100
  Re: filling area by color atack safety Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-03-16 11:33 +0000
    Re: filling area by color atack safety Ben Bacarisse <ben.usenet@bsb.me.uk> - 2024-03-16 13:55 +0000
      Re: filling area by color atack safety bart <bc@freeuk.com> - 2024-03-16 14:41 +0000
        Re: filling area by color atack safety Ben Bacarisse <ben.usenet@bsb.me.uk> - 2024-03-17 10:42 +0000
        Re: filling area by color atack safety Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-18 03:00 -0700
          Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-18 14:23 +0200
            Re: filling area by color atack safety Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-18 14:13 -0700
            Re: filling area by color atack safety fir <fir@grunge.pl> - 2024-03-19 16:05 +0100
              Re: filling area by color atack safety bart <bc@freeuk.com> - 2024-03-19 17:16 +0000
                Re: filling area by color atack safety bart <bc@freeuk.com> - 2024-03-19 17:33 +0000
                Re: filling area by color atack safety fir <fir@grunge.pl> - 2024-03-19 23:07 +0100
                Re: filling area by color atack safety David Brown <david.brown@hesbynett.no> - 2024-03-20 09:29 +0100
        Re: filling area by color atack safety Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-18 03:04 -0700
      Re: filling area by color atack safety Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-03-16 14:45 +0000
        Re: filling area by color atack safety scott@slp53.sl.home (Scott Lurndal) - 2024-03-16 18:21 +0000
          Re: filling area by color atack safety Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-03-16 20:02 +0000
            Re: filling area by color atack safety "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-03-16 13:29 -0700
              Re: filling area by color atack safety "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-03-17 13:19 -0700
                Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-18 14:40 +0200
            Re: filling area by color atack safety fir <fir@grunge.pl> - 2024-03-19 23:23 +0100
          Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-17 15:32 +0200
        Re: filling area by color atack safety Ben Bacarisse <ben.usenet@bsb.me.uk> - 2024-03-17 11:25 +0000
          Re: filling area by color atack safety Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-03-17 12:37 +0000
            Re: filling area by color atack safety Kaz Kylheku <433-929-6894@kylheku.com> - 2024-03-17 17:11 +0000
            Re: filling area by color atack safety Ben Bacarisse <ben.usenet@bsb.me.uk> - 2024-03-23 00:21 +0000
            Re: filling area by color atack safety scott@slp53.sl.home (Scott Lurndal) - 2024-03-23 14:43 +0000
              Re: filling area by color atack safety Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-23 11:48 -0700
                Re: filling area by color atack safety scott@slp53.sl.home (Scott Lurndal) - 2024-03-24 20:48 +0000
                Re: filling area by color atack safety Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-28 22:51 -0700
    Re: filling area by color atack safety David Brown <david.brown@hesbynett.no> - 2024-03-16 15:40 +0100
      Re: filling area by color atack safety Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-03-16 15:09 +0000
        Re: filling area by color atack safety Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-03-17 14:56 +0000
          Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-17 17:42 +0200
          Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-17 18:25 +0200
            Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-17 19:39 +0200
              Re: filling area by color atack safety Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-18 11:36 -0700
                Re: filling area by color atack safety Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-03-18 18:51 +0000
                Re: filling area by color atack safety Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-18 23:10 -0700
                Re: filling area by color atack safety Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-03-19 12:06 +0000
            Re: filling area by color atack safety fir <fir@grunge.pl> - 2024-03-20 00:03 +0100
              Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-20 01:17 +0200
                Re: filling area by color atack safety fir <fir@grunge.pl> - 2024-03-20 00:30 +0100
                Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-20 12:06 +0200
                Re: filling area by color atack safety fir <fir@grunge.pl> - 2024-03-20 13:44 +0100
                Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-20 15:44 +0200
                Re: filling area by color atack safety fir <fir@grunge.pl> - 2024-03-20 15:17 +0100
          Re: filling area by color atack safety fir <fir@grunge.pl> - 2024-03-20 02:15 +0100
        Re: filling area by color atack safety David Brown <david.brown@hesbynett.no> - 2024-03-17 17:45 +0100
          Re: filling area by color atack safety Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-03-17 18:28 +0000
            Re: filling area by color atack safety David Brown <david.brown@hesbynett.no> - 2024-03-18 07:58 +0100
              Re: filling area by color atack safety Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-03-18 09:26 +0000
                Re: filling area by color atack safety David Brown <david.brown@hesbynett.no> - 2024-03-18 17:28 +0100
                Re: filling area by color atack safety Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-03-18 17:25 +0000
                Re: filling area by color atack safety scott@slp53.sl.home (Scott Lurndal) - 2024-03-18 17:42 +0000
                Re: filling area by color atack safety bart <bc@freeuk.com> - 2024-03-18 18:50 +0000
                Re: filling area by color atack safety David Brown <david.brown@hesbynett.no> - 2024-03-19 11:41 +0100
                Re: filling area by color atack safety Richard Harnden <richard.nospam@gmail.invalid> - 2024-03-19 12:19 +0000
                Re: filling area by color atack safety Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-03-18 11:10 -0700
                Keith-world (Was: filling area by color atack safety) gazelle@shell.xmission.com (Kenny McCormack) - 2024-03-18 22:42 +0000
                Re: filling area by color atack safety David Brown <david.brown@hesbynett.no> - 2024-03-19 12:31 +0100
                Re: filling area by color atack safety "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-03-18 16:18 -0700
                Re: filling area by color atack safety David Brown <david.brown@hesbynett.no> - 2024-03-19 11:32 +0100
      Re: filling area by color atack safety scott@slp53.sl.home (Scott Lurndal) - 2024-03-16 18:25 +0000
        Re: filling area by color atack safety Ben Bacarisse <ben.usenet@bsb.me.uk> - 2024-03-17 10:31 +0000
          Re: filling area by color atack safety Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-03-17 12:28 +0000
            Re: filling area by color atack safety bart <bc@freeuk.com> - 2024-03-17 12:49 +0000
          Re: filling area by color atack safety David Brown <david.brown@hesbynett.no> - 2024-03-17 17:59 +0100
      Re: filling area by color atack safety fir <fir@grunge.pl> - 2024-03-19 23:52 +0100
        Re: filling area by color atack safety fir <fir@grunge.pl> - 2024-03-20 01:36 +0100
    Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-17 14:46 +0200
      Re: filling area by color atack safety bart <bc@freeuk.com> - 2024-03-17 12:54 +0000
        Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-17 15:15 +0200
          Re: filling area by color atack safety bart <bc@freeuk.com> - 2024-03-17 13:23 +0000
            Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-17 15:37 +0200
              Re: filling area by color atack safety David Brown <david.brown@hesbynett.no> - 2024-03-17 18:05 +0100
            Re: filling area by color atack safety Ben Bacarisse <ben.usenet@bsb.me.uk> - 2024-03-17 14:10 +0000
              Re: filling area by color atack safety Spiros Bousbouras <spibou@gmail.com> - 2024-03-17 16:58 +0000
                Re: filling area by color atack safety Ben Bacarisse <ben.usenet@bsb.me.uk> - 2024-03-17 22:14 +0000
                Re: filling area by color atack safety bart <bc@freeuk.com> - 2024-03-17 22:21 +0000
      Re: filling area by color atack safety Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-18 02:30 -0700
        Re: filling area by color atack safety Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-03-18 11:08 +0000
          Re: filling area by color atack safety Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-18 22:54 -0700
            Re: filling area by color atack safety Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-03-19 11:41 +0000
              Re: filling area by color atack safety Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-19 21:19 -0700
      Re: filling area by color atack safety fir <fir@grunge.pl> - 2024-03-20 01:13 +0100
        Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-20 10:41 +0200
          Re: filling area by color atack safety fir <fir@grunge.pl> - 2024-03-20 15:20 +0100
    Re: filling area by color atack safety Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2024-03-17 14:27 +0000
      Re: filling area by color atack safety bart <bc@freeuk.com> - 2024-03-17 15:13 +0000
      Re: filling area by color atack safety Peter 'Shaggy' Haywood <phaywood@alphalink.com.au> - 2024-03-19 10:57 +1100
        Re: filling area by color atack safety fir <fir@grunge.pl> - 2024-03-20 01:26 +0100
  Re: filling area by color atack safety bart <bc@freeuk.com> - 2024-03-16 19:13 +0000
    Re: filling area by color atack safety bart <bc@freeuk.com> - 2024-03-16 20:23 +0000
      Re: filling area by color atack safety Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-03-16 20:29 +0000
    Re: filling area by color atack safety fir <fir@grunge.pl> - 2024-03-20 01:48 +0100
      Re: filling area by color atack safety Peter 'Shaggy' Haywood <phaywood@alphalink.com.au> - 2024-03-22 13:04 +1100
        Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-22 17:55 +0300
          Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-22 18:31 +0300
        Re: filling area by color atack safety fir <fir@grunge.pl> - 2024-03-23 11:06 +0100
  Re: filling area by color atack safety Peter 'Shaggy' Haywood <phaywood@alphalink.com.au> - 2024-03-17 18:03 +1100
  Re: filling area by color atack safety Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-18 13:09 -0700
    Re: filling area by color atack safety Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-18 22:42 -0700
      Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-19 13:18 +0200
        Re: filling area by color atack safety Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-03-19 11:57 +0000
          Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-19 15:49 +0200
            Re: filling area by color atack safety Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-19 21:43 -0700
              Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-20 10:56 +0200
                Re: filling area by color atack safety Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-20 06:51 -0700
          Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-19 19:18 +0200
            Re: filling area by color atack safety fir <fir@grunge.pl> - 2024-03-20 09:27 +0100
              Re: filling area by color atack safety fir <fir@grunge.pl> - 2024-03-20 09:39 +0100
              Re: filling area by color atack safety fir <fir@grunge.pl> - 2024-03-20 09:51 +0100
            Re: filling area by color atack safety Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-20 07:27 -0700
              Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-24 20:27 +0300
                Re: filling area by color atack safety Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-24 13:26 -0700
                Re: filling area by color atack safety "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-03-24 14:26 -0700
                Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-25 01:28 +0300
                Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-26 17:52 +0200
                Re: filling area by color atack safety Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-30 00:54 -0700
                Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-30 21:26 +0300
                Re: filling area by color atack safety Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-04-09 01:00 -0700
                Re: filling area by color atack safety Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-28 23:04 -0700
                Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-29 15:21 +0200
                Re: filling area by color atack safety Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-29 23:58 -0700
                Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-30 21:15 +0300
                Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-31 10:54 +0200
                Re: filling area by color atack safety Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-04-09 02:32 -0700
                Re: filling area by color atack safety Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-04-09 01:55 -0700
                Re: filling area by color atack safety Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-30 11:59 -0700
            Re: filling area by color atack safety Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-20 10:26 -0700
              Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-21 15:36 +0200
                Re: filling area by color atack safety Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-21 09:47 -0700
        Re: filling area by color atack safety Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-19 21:40 -0700
          Re: filling area by color atack safety "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-03-19 21:43 -0700
            Re: filling area by color atack safety "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-03-19 21:48 -0700
          Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-20 11:54 +0200
            Re: filling area by color atack safety Ben Bacarisse <ben.usenet@bsb.me.uk> - 2024-03-20 10:23 +0000
              Re: filling area by color atack safety Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-03-20 12:06 +0000
              Re: filling area by color atack safety Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-20 07:52 -0700
            Re: filling area by color atack safety Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-20 10:01 -0700
              Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-24 19:33 +0300
                Re: filling area by color atack safety Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-24 10:24 -0700
                Re: filling area by color atack safety Michael S <already5chosen@yahoo.com> - 2024-03-25 01:04 +0300
                Re: filling area by color atack safety - worst memory size Michael S <already5chosen@yahoo.com> - 2024-04-05 17:30 +0300
                Re: filling area by color atack safety - worst memory size Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-04-10 19:47 -0700
                Re: filling area by color atack safety - worst memory size Michael S <already5chosen@yahoo.com> - 2024-04-11 15:20 +0300

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