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From: Blue-Maned_Hawk <bluemanedhawk@invalid.invalid>
Newsgroups: comp.lang.c
Subject: Re: on allowing "int a" definition everywhere
Date: Thu, 22 Aug 2024 08:40:30 -0000 (UTC)
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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, …);

Therefore, your example does not work as evidence in favor of declarations 
in if statement controlling expressions because it's already possible in 
other ways.

-- 
Blue-Maned_Hawk│shortens to Hawk│/blu.mɛin.dʰak/│he/him/his/himself/Mr.
blue-maned_hawk.srht.site
Banned in the UK for several years!