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From: David Brown <david.brown@hesbynett.no>
Newsgroups: comp.lang.c
Subject: Re: how cast works?
Date: Fri, 9 Aug 2024 19:12:47 +0200
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On 09/08/2024 12:04, Bart wrote:
> On 09/08/2024 00:17, Keith Thompson wrote:
>> Bart <bc@freeuk.com> writes:
>> [...]
>>> Take:
>>>
>>>      int a; double x;
>>>
>>>      x = (double)a;
>>>
>>> The cast is implicit here but I've written it out to make it clear.
>>
>> [...]
>>
>> The *conversion* could be done implicitly, but you've used a cast (i.e.,
>> an explicit conversion) to make it clear.
>>
>> There is no such thing as an "implicit cast" in C.
>>
> 
> Suppose I write this code:
> 
>      x = a;                  // implicit 'conversion'
>      x = (double)a;          // explicit 'conversion'
> 
> 
> My compiler produces these two bits of AST for the RHS of both expressions:
> 
> 1 00009 r64---|---2 convert: sfloat_c i32 => r64
> 1 00009 i32---|---|---1 name: t.main.a.1
> 
> 1 00010 r64---|---2 convert: sfloat_c i32 => r64
> 1 00010 i32---|---|---1 name: t.main.a.1
> 
> So whatever you call that `(double)` part of the second line, which is 
> written explicitly, exactly the same thing is done internally (ie 
> 'implicitly') to the first line. (The 09/10 are line numbers.)
> 

You've written it yourself.  Both are conversions - one is implicit, the 
other is explicit.

> Since C likes to use the term 'cast' for such conversions, I don't see a 
> problem with talking about implicit and explicit versions.
>

C does not "like" to use the term "cast" for anything other than cast 
operations, as defined by the C standards.  Implicit conversions are not 
casts.

/You/ might like to call implicit conversions "casts", but you'd be 
wrong to do so.

> It just seems to irk the pedantics here.

You mean, people who know what they are talking about rather than those 
that make up stuff as they go along?