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From: fir <fir@grunge.pl>
Newsgroups: comp.lang.c
Subject: Re: on allowing "int a" definition everywhere
Date: Fri, 23 Aug 2024 12:47:55 +0200
Organization: i2pn2 (i2pn.org)
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Bart wrote:
> On 22/08/2024 09:40, Blue-Maned_Hawk wrote:
>> Thiago Adams wrote:
>>
>>> On 21/08/2024 01:42, Blue-Maned_Hawk wrote:
>>>> Thiago Adams wrote:
>>>>
>>>>> initializer inside if is already in C++, and it will probably be on
>>>>> C2Y.
>>>> If it's for consistency with how for loops permit declarations, i would
>>>> _much_  prefer that they just outlaw that to induce consistency.
>>>>
>>>> (Really, i'd ideally want things to just stay as they are, since
>>>> declarations in for loops are simply too useful for macros.)
>>>
>>> I like the ability to declare things inside if.
>>>
>>> if (FILE* f = fopen("file.txt", "r"))
>>> {
>>>     /*...*/ fclose(f);
>>> }
>>>
>>> Because it makes the scope of f, associated with the pointed object
>>> lifetime.
>>>
>>> For instance, if you try to use f
>>>
>>> if (FILE* f = fopen("file.txt", "r"))
>>> {
>>>     /*...*/ fclose(f);
>>> }
>>> fwrite(f, ..) ;// ERROR
>>
>> You can already do that in C23:
>>
>> if (…) {
>>     FILE * f = fopen("file.txt", "r");
>>     /* … */
>>     fclose(f);
>> }
>> fwrite(f, …);  /* Some kind of error happens. */
>>
>> Or, if you need it to exist before the controlling expression:
>>
>> for (bool x = true; x; x = false)  for (FILE * f = fopen("file.txt",
>> "r");
>> x; x = false)  if (…) {
>>     /* … */
>>     fclose(f);
>> }
>> fwrite(f, …);
>>
>
> I wonder, if I laid it out it properly:
>
>      for (bool x = true; x; x = false)
>          for (FILE * f = fopen("file.txt", "r"); x; x = false)
>              if (…) {
>                  /* … */
>                  fclose(f);
>              }
>      fwrite(f, …);
>
> Nope; I still haven't the faintest idea what this is supposed to do. I
> suspect that it doesn't actually run or need those two nested loops.
>
> I assume the (...) tests the value of 'f'? If so then perhaps this is a
> shorter way of expressing the same thing:
>
>      {
>          FILE * f = fopen("file.txt", "r");
>          if (f) {
>              /* … */
>              fclose(f);
>          }
>      }
>      fwrite(f, …);
>

btw maybe not so much relevent as what you write but
if to think the convention


foir(int i=0; i<100; i++)
{
   //,,,
}

to amke int i scope relevant to only inner of the loop seem just 
logically wrong

on assembly lebel you got outside of the loop inside of the loop
and loop code itself


loop:
    ....

   cmp ecx, 100
   jl loop


tehnically the loop as it can be breal it is more like that the loop 
counter may be just the result needed in the outside - so logical bug in 
c was here spotted