Re: Checking the loop variable after the loop has ended (Was: Loops (was Re: do { quit; } else { }))

On 18.04.2025 17:57, bart wrote:

On 18/04/2025 16:24, Kaz Kylheku wrote:

On 2025-04-17, Lew Pitcher <lew.pitcher@digitalfreehold.ca> wrote:

[...]

[...]
   for (n = NUM_ENTRIES - 1; ...

 
That looks like another inconsistency in the syntax (and another error
opportunity).
 
Since the loop for upward and downward iterations between 0 and N-1
inclusve would be:
 
   for (i = 0;   i <  N; ++i)
   for (i = N-1; i >= 0; --i)
 
'N-1' is what I would have to write; it's odd that C people have write
it too. Unless perhaps you do this:
 
   for (i = N; i-- > 0;)
 
Here you now have a genuine 2-part loop!
 
I guess this is C being 'flexible', in being able to reinvent for-loops
each time.

It is perfectly fine to write your loops in "C" as

    for (i = 1; i <= N; ++i)
    for (i = N; i >= 1; --i)

(and access your array elements as [i-1] if you wish).

You should be aware that the problem you have here is *not* a "C"
"loop-problem", it's a problem of the low-level _"C" arrays_ you
have to use; they force you to define and use bounds of 0 and N-1
respectively if you want to use an array of N elements.

Try to address the issues to the correct source of "C" constructs.
The loop flexibility allows you to address such "array-crudeness",
it is not the source of the problem, neither here nor generally.

Janis