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Re: What is a `**ppEnum`?

From T <T@invalid.invalid>
Newsgroups comp.lang.c++
Subject Re: What is a `**ppEnum`?
Date 2022-11-17 10:28 -0800
Organization A noiseless patient Spider
Message-ID <tl5uh4$2mr5f$1@dont-email.me> (permalink)
References (3 earlier) <ff8b48f4-e2f9-4ae9-865d-7e657f4ac1c0n@googlegroups.com> <tkt73c$1o60i$2@dont-email.me> <tl2bj1$1en4$1@gioia.aioe.org> <tl3t9g$2f98u$1@dont-email.me> <87v8ndu41f.fsf@bsb.me.uk>

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On 11/17/22 05:03, Ben Bacarisse wrote:
> T <T@invalid.invalid> writes:
> 
>> The only thing I am not following, is how do I know the
>> length of each item in the array and how many items are
>> in the array.
> 
> I typed this up before seeing Mike's reply.  It seems this has been
> covered more than once, but since I've typed it already...
> 
> Do you understand the concept of using a pointer to "return" a value
> from a function?  For example
> 
>    int get_some_fancy_hardware_value(long *res);
> 
> This interface return success (0) or some negative value indicating an
> error so the return value can't be used to get the fancy value out of the
> hardware.  Instead, it's placed in the long pointed to by the long *
> argument.  You'd write:
> 
>    long hw_val;
>    if (get_some_fancy_hardware_value(&hw_val) >= 0)
>         printf("value=%ld\n", hw_val);
>    else fprintf(stderr, "Could not get hardware value.\n");
> 
> Sometimes the value you want to get out is itself a pointer.  In these
> cases that argument will be a pointer to a pointer, as in your example.
> 


I found this example that follows what you guys have been
trying to get through my thick skull:

      if (!WTSEnumerateSessions(WTS_CURRENT_SERVER, 0, 1, &pwsi, &dwCount))
      {
          Report(_T("WTSEnumerateSessions failed with error code %d\n"), 
GetLastError());
          return 0;
      }

      for (DWORD i = 0; i < dwCount; i++)
      {
          if (pwsi[i].State == WTSActive)
          {
              dwSession = pwsi[i].SessionId;
              break;
          }
      }

      WTSFreeMemory(pwsi);

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What is a `**ppEnum`? T <T@invalid.invalid> - 2022-11-14 00:39 -0800
  Re: What is a `**ppEnum`? "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2022-11-14 01:29 -0800
    Re: What is a `**ppEnum`? T <T@invalid.invalid> - 2022-11-14 01:46 -0800
      Re: What is a `**ppEnum`? "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2022-11-14 01:52 -0800
        Re: What is a `**ppEnum`? "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2022-11-14 01:55 -0800
      Re: What is a `**ppEnum`? Öö Tiib <ootiib@hot.ee> - 2022-11-14 02:30 -0800
        Re: What is a `**ppEnum`? T <T@invalid.invalid> - 2022-11-14 02:38 -0800
          Re: What is a `**ppEnum`? Öö Tiib <ootiib@hot.ee> - 2022-11-14 02:48 -0800
  Re: What is a `**ppEnum`? Öö Tiib <ootiib@hot.ee> - 2022-11-14 01:39 -0800
    Re: What is a `**ppEnum`? T <T@invalid.invalid> - 2022-11-14 01:48 -0800
      Re: What is a `**ppEnum`? "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2022-11-14 02:01 -0800
      Re: What is a `**ppEnum`? Öö Tiib <ootiib@hot.ee> - 2022-11-14 02:33 -0800
        Re: What is a `**ppEnum`? T <T@invalid.invalid> - 2022-11-14 02:59 -0800
          Re: What is a `**ppEnum`? Öö Tiib <ootiib@hot.ee> - 2022-11-14 03:33 -0800
            Re: What is a `**ppEnum`? T <T@invalid.invalid> - 2022-11-14 11:10 -0800
          Re: What is a `**ppEnum`? Juha Nieminen <nospam@thanks.invalid> - 2022-11-16 09:47 +0000
            Re: What is a `**ppEnum`? T <T@invalid.invalid> - 2022-11-16 15:55 -0800
              Re: What is a `**ppEnum`? scott@slp53.sl.home (Scott Lurndal) - 2022-11-17 00:19 +0000
              Re: What is a `**ppEnum`? Mike Terry <news.dead.person.stones@darjeeling.plus.com> - 2022-11-17 01:21 +0000
                Re: What is a `**ppEnum`? T <T@invalid.invalid> - 2022-11-16 18:01 -0800
                Re: What is a `**ppEnum`? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-11-16 18:40 -0800
                Re: What is a `**ppEnum`? Mike Terry <news.dead.person.stones@darjeeling.plus.com> - 2022-11-17 04:18 +0000
              Re: What is a `**ppEnum`? Juha Nieminen <nospam@thanks.invalid> - 2022-11-17 08:25 +0000
                Re: What is a `**ppEnum`? T <T@invalid.invalid> - 2022-11-17 00:31 -0800
                Re: What is a `**ppEnum`? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-11-17 10:17 -0800
              Re: What is a `**ppEnum`? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-11-17 13:03 +0000
                Re: What is a `**ppEnum`? T <T@invalid.invalid> - 2022-11-17 10:28 -0800
          Re: What is a `**ppEnum`? Mike Terry <news.dead.person.stones@darjeeling.plus.com> - 2022-11-17 03:36 +0000
            Re: What is a `**ppEnum`? T <T@invalid.invalid> - 2022-11-16 20:57 -0800
  Re: What is a `**ppEnum`? "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2022-11-14 14:34 +0100
    Re: What is a `**ppEnum`? "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2022-11-14 14:44 +0100
    Re: What is a `**ppEnum`? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-11-14 09:12 -0800
    Re: What is a `**ppEnum`? T <T@invalid.invalid> - 2022-11-14 11:02 -0800
      Re: What is a `**ppEnum`? Ralf Fassel <ralfixx@gmx.de> - 2022-11-15 10:17 +0100
        Re: What is a `**ppEnum`? Öö Tiib <ootiib@hot.ee> - 2022-11-15 04:24 -0800
      Re: What is a `**ppEnum`? "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2022-11-15 14:04 +0100
        Re: What is a `**ppEnum`? T <T@invalid.invalid> - 2022-11-15 08:28 -0800
          Re: What is a `**ppEnum`? "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2022-11-17 16:21 +0100
            Re: What is a `**ppEnum`? T <T@invalid.invalid> - 2022-11-17 16:39 -0800
              Re: What is a `**ppEnum`? "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2022-11-19 14:16 +0100

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