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From: David Brown <david.brown@hesbynett.no>
Newsgroups: comp.lang.c
Subject: Re: "A diagram of C23 basic types"
Date: Fri, 4 Apr 2025 15:38:52 +0200
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On 04/04/2025 04:50, Janis Papanagnou wrote:
> On 03.04.2025 11:03, David Brown wrote:
>> On 02/04/2025 23:43, Janis Papanagnou wrote:
>>> On 02.04.2025 16:59, David Brown wrote:
>>>> [...]
>>>>
>>>>   From the next version beyond C23, so far there is :
>>>>
>>>> 1. Declarations in "if" and "switch" statements, like those in "for"
>>>> loops, helps keep local variable scopes small and neat.
>>>
>>> Oh, I thought that would already be supported in some existing "C"
>>> version for the 'if'; I probably confused that with C++.
>>>
>>
>> C++17 has it.
>>
>> I guess the C committee waited until C++17 had been common enough that
>> they could see if it was useful in real code, and if it lead to any
>> unexpected problems in code or compilers before copying it for C.
> 
> Really, that recent!? - I was positive that I used it long before 2017
> during the days when I did quite regularly C++ programming. - Could it
> be that some GNU compiler (C++ or "C") supported that before it became
> C++ standard?
> 
> Janis
> 

To be clear, we are talking about :

	if (int x = get_next_value(); x > 10) {
		// We got a big value!
	}

It was added in C++17.  <https://en.cppreference.com/w/cpp/language/if>

gcc did not have it as an extension, but they might have had it in the 
pre-standardised support for C++17 (before C++17 was published, gcc had 
"-std=c++1z" to get as many proposed C++17 features as possible before 
they were standardised.  gcc has similar "pre-standard" support for all 
C and C++ versions).