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

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

On Thu, 17 Apr 2025 21:21:54 +0000, Kenny McCormack wrote:
>

In article <87fri68w2c.fsf@nosuchdomain.example.com>,
Keith Thompson  <Keith.S.Thompson+u@gmail.com> wrote:
...

IMHO it doesn't much matter what the value is after the loop ends, but
any standard for a language with such a feature should either restrict
the scope to the loop, specify the value the variable has after the
loop, or explicitly say that it's unspecified or undefined.

 
I frequently check the value of the loop variable after the loop has ended
in order to determine if the loop ended "normally" or prematurely via
"break".  E.g.,
 
    for (i=0; i<10; i++) { code that might or might not break }
    if (i == 10) puts("It ended normally");

>
It's also a handy idiom for a compact list search loop
where the terminating condition is either end of the list, or
a matched entry.
If the cursor isn't the end-of-list marker, then it references
the matched entry;
>
  for (n = NUM_ENTRIES; (n >= 0) && (node[n] != key); --n) continue;

You're saying that the number of entries in the array isn't
NUM_ENTRIES but NUM_ENTRIES + 1, since you're accessing node[0]
and node[NUM_ENTRIES]

Don't you want:

  for (n = NUM_ENTRIES - 1; ...

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