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

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;
  if (n != -1) printf("Found key at entry %d\n",n);

I've applied this method in many C and (vaguely) C-like languages.
Any language with a "for" type loop, where you can check the value after
the loop can avail themselves of this method.

I concur :-)

--
Lew Pitcher
"In Skills We Trust"