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From: Tim Rentsch <tr.17687@z991.linuxsc.com>
Newsgroups: comp.lang.c
Subject: Re: Loops (was Re: do { quit; } else { })
Date: Sun, 11 May 2025 17:30:14 -0700
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Michael S <already5chosen@yahoo.com> writes:

> On Sat, 10 May 2025 06:43:38 -0700
> Tim Rentsch <tr.17687@z991.linuxsc.com> wrote:
>
>> Michael S <already5chosen@yahoo.com> writes:
>>
>>> On Sun, 04 May 2025 07:31:11 -0700
>>> Tim Rentsch <tr.17687@z991.linuxsc.com> wrote:
>>> [...]
>>> Also having just one form of loop with pre-condition strikes me as
>>> more elegant.  Since elegance is strongly subjective, I have no
>>> logical arguments in support of me feelings.
>>
>> In a recent posting I gave some statistics about the three different
>> kinds of looping controls (while,for,do/while).  do/while loops were
>> almost 20% of all loops, and more than a quarter of the two kinds of
>> loops other than for().  Besides being a more pragmatic choice, I
>> think having the three kinds of loops be distinct in the language is
>> a better choice, because how we think of the different kinds of loop
>> is different, and it's helpful to have those differences be readily
>> apparent in the program, rather than needing to reconstruct them by
>> looking at code around the loop control fragment.
>
> That sounds like misunderstanding.
> I didn't suggest one loop construct.  I suggested two constructs:  for()
> for loops with pre-condition and do-while for loops with post-condition.

Yes, I did misunderstand you.  The alternative meaning didn't occur
to me.  I see it now.

The same posting I mentioned in the previous response gave while()
loops as occurring more than for() and do/while() combined.  I
conceptualize for() loops quite differently than while() loops, and
vice versa.  By analogy to the only-two-kinds-of-loops suggestion,
the language could forego switch() and provide only if()/else.  To
me, neither of those what-might-be-called-simplifications seems like
a good trade.  Have you asked other people to see what their
reactions are?

Incidentally, a language change to C was once proposed, so that
a do/while could also have an expression after the while().
Note that this change is backwards compatible with C as it is,
because a simple semicolon after while() is an empty statement.
Adopting this proposal would mean that the language would allow,
for example

   do {
      // this part will always be done at least once
      // and once more for each time 'condition' is true
   } while(  condition  ){
      // this part will be done zero or more times
   }

allowing a convenient way of writing "loop-and-a-half" type
loops.  Do you have any reaction to this idea?  Suppose
the just plain while() style were eliminated, so ordinary
while() loops would instead be written as

   do ; while( condition ){
      // body of while loop
   }

Is that better or worse than having a separate while() statement?