Re: Loops (was Re: do { quit; } else { })

On 15/04/2025 08:17, Janis Papanagnou wrote:

On 14.04.2025 17:22, bart wrote:

On 14/04/2025 13:18, Janis Papanagnou wrote:

(While there's some "C" stuff in here it contains a lot of non-"C"
samples for comparison. So [OT]-sensible folks may want to skip this
post.)

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[...]

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I'm not saying there's anything wrong with it. The point was that an A
to B loop existed in the 1950s; C came out in the 1970s!
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which of course would be written with a 'while'
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    int i = a;
    while (i <= b) f(i++)

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That would be a poor use of 'while'.

 Not the least.
 

And bizarre, to use 'while' for
iteration, but 'for' for loops that are best written as while!

 I was merely trying to provide some options to address your dislike.
 

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The "C" syntax has actually a flexibility that is very valuable.

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The flexibility is the problem, because you have to specify the loop in
such excruciating detail. It is easy to make a mistake which results in
still legal code. And you now have to analyse each loop to see what kind
of loop it is:

 Well, our opinions obviously differ. I just give you two examples
(and there's many variants of these) of not uncommon 'for' usages...
      for (c=0; bitstr; c++)
         bitstr &= bitstr-1;

I can't grok that.

     for (r=1; r<=0x80; r<<=1)
         ...

and someone already posted another iteration type on linked lists
      for (node = list; node; node = node->next)

These two I get, and I can tell you that they're all WHILE loops. To make make them tidier, I'd have fewer complaints about them if they instead looked like this:
   while (node = list; node; node = node->next)
So, you can optionally add extra elements to a while (x).
It would be necessary to either define whether while(x; y) means while (; x; y) or while (x; y), or to always require either zero or two semicolons inside (...).
That could have kept 'for' for how it works in other languages (the ones that haven't just blindly copied C's version!).

The point here is the observation that there are loops that deviate
from simple counted loops (and that are commonly used) and that they
all comprise the same principal structure; initialization, condition
test, change of loop-variables. The "C" loop syntax reflects that in
its typical low-level syntax form. (I already said that personally I
don't like "C"'s syntax, but I do like its flexibility.)

Let me ask you this: what exactly is the point of the 'while' statement in C? Since it can always be trivially be written as:
    for (;cond;)
It seems to that most use cases (initialise, check exit condition, change something that affects the letter), would suit 'for' better.
But since 'for' then becomes overloaded, there ought to be a dedicated feature for simple iteration. So it seems the solution is as a I suggested above.

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Suppose you see 'i <= N' as the condition; is that '<=' intentional, or
is it a typo for '<'? It's impossible to tell.

 (This is nonsense.)

You can't just say that without explanation. WHY it it nonsense? Take this:
   for (i=0 i<=N; ++i)
Most such loops iterate over 0..N-1 inclusive, so would need "<". So, in your opinion, is that <= a typo, or is the intention to iterate over 0..N inclusive (so N+1 iterations)?
(May reply to rest separately.)