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From: Bart <bc@freeuk.com>
Newsgroups: comp.lang.c
Subject: Re: how cast works?
Date: Fri, 9 Aug 2024 11:04:35 +0100
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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.)

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

It just seems to irk the pedantics here.