Re: size_t best practice

On Sun, 18 Aug 2024 15:23:58 -0700
Tim Rentsch <tr.17687@z991.linuxsc.com> wrote:

Michael S <already5chosen@yahoo.com> writes:
 

On 18 Aug 2024 12:17:36 GMT
ram@zedat.fu-berlin.de (Stefan Ram) wrote:
 

Mark Summerfield <mark@qtrac.eu> wrote or quoted:
 

So is it considered best practice to use int, long, long long, or
size_t, in situations like these? 

>
  In *cough*C++*cough* you could whip up a "SafeSize" class with
  a bulletproof "operator--", so you don't space on the check.
  You could still keep cranking out your code in what's basically C
and just cherry-pick this one gnarly feature from that other
language.
>
SafeSize& operator--()
{ if( value == 0 )
  { throw std::underflow_error("SafeSize decrement underflow"); }
  --value;
  return *this; } 

>
But that's not a desired behavior for people that want to write
downcounting for() loops in intuitive manner. 

 
Kind of a funny use of the word intuitive, for two reasons.
 
The first is that writing for() loops, especially C for() loops,
is learned behavior.  There can be patterns that one is used to,
but they are not "intuitive" in the usual sense of the word.
 
The second is that people who program in C are accustomed to the
idea of an asymmetry between counting up and counting down,
because of how pointers work.  It's okay to increment a pointer
to one past the end of an array;  it is not okay to decrement a
pointer to one before the beginning of an array.  Because of that
the patterns for going forward and for going backward are just
different.  It seems odd to use the word "intuitive" to recognize
that distinction.
>

I would think that very large part of 'C' programmers ignores this
asymmetry. They are helped by the fact that 100% of production 'C'
compilers ignore it as well, which means that in practice code that
compares &arr[0] with &arr[-1] works as naively expected on all targets
that have flat memory model and far more often than not works on more
tricky targets as well.

Which is not to say I disagree with what you are saying.  Actually
I guess I'd have to say I'm not sure what it is you are saying.
To my way of thinking the function above doesn't change the way I
would write down-counting loops.  It might be useful as a debugging
aid aide, but nothing more (and an assert() is probably better).
I think though that what you're saying is something else but I'm
not sure what it is.

Nothing fancy. Just an ability to write downcounting loops in a
way that I, obviously mistakenly, consider intuitive.
for (i = len-1; i >= 0; --i)