Re: how cast works?

On 08/08/2024 22:34, Thiago Adams wrote:

On 08/08/2024 16:42, Keith Thompson wrote:

Thiago Adams <thiago.adams@gmail.com> writes:

On 07/08/2024 17:00, Dan Purgert wrote:

On 2024-08-07, Thiago Adams wrote:

[...]

How about floating point?

Floating point is a huge mess, and has a few variations for
encoding;
though I think most C implementations use the one from the IEEE on 1985
(uh, IEEE754, I think?)

>
I didn't specify properly , but my question was more about floating
point registers. I think in this case they have specialized registers.

>
Who is "they"?
>
Some CPUs have floating-point registers, some don't.  C says nothing
about registers.
>
What exactly is your question?  Is it not already answered by reading
the "Conversions" section of the C standard?
>

  This part is related with the previous question about the origins of integer promotions.
 We don't have "char" register or signed/unsigned register. But I believe we may have double and float registers. So float does not need to be converted to double.
 There is no specif question here, just trying to understand the rationally behind the conversions rules.
 

Stop trying to think about registers or implementations until you have understood the meaning of the conversions, as detailed in the C standards.  Implementation details are just that - implementation details, which vary from target to target, compiler to compiler, and according to the circumstances and the rest of the surrounding code.
In general, conversions try to preserve values (with the exceptions and limitations detailed in the standards).  If that involves changing the underlying bit representations, then those changes are made.  If no changes are needed, no changes will be made.