the difference between posix user and c user

[Gedare Bloom]

On Thu, Dec 28, 2017 at 9:35 PM, bin.wang at qkmtech.com
<bin.wang at qkmtech.com> wrote:
> is the posix api and the c api used together?
>
POSIX and ISO-C tend to go together.

With RTEMS, you can also use ISO-C with the "Classic API", which
consists of interface functions accessible from C programs as
described in the "C User Guide".

> sorry . i am also confused about this two things . because i find that when
> i config the rtems kernel ,there is a option which is  --enable posix.
>
Most new development and ports of existing software probably use POSIX
anyway, except for the simplest applications. This configure option
was provided historically as a way to avoid compiling the POSIX
library into an application, but modern compilers are able to remove
the unused code any way.

> ________________________________
> bin.wang at qkmtech.com
>
>
> From: bin.wang at qkmtech.com
> Date: 2017-12-29 09:25
> To: Chris Johns; Users
> Subject: Re: Re: the difference between posix user and c user
> i google the posix .now i know that posix is the abbreviation of "the
> Portable Operating System Interface" it is for software compatibility with
> variants of Unix and other operating systems
>
> but you said, "POSIX and the Classic API are both C APIs."
> than i think the posix is packaged on the basis of the standard C, is it
> right ?
> the classic api is the standard c interface , is it right?
>
> best wishes
>
> ________________________________
> bin.wang at qkmtech.com
>
>
> From: Chris Johns
> Date: 2017-12-29 02:18
> To: users
> Subject: Re: the difference between posix user and c user
> On 29/12/17 12:00 am, bin.wang at qkmtech.com wrote:
>> hi everyone:
>>
>> i am new to linux and rtems. i do not understand
>> what the difference between posix user and c user .
>>
>> i am confused about these two concept. which condition i should choose
>> posix ?
>> which condition i should choose c ?
>>
>
> This is a good question and it is understandable why you do not understand
> the
> difference. The reason is specific to RTEMS and relates to it's history.
>
> The original RTEMS was written in Ada and C and the C API is what we now
> call
> the Classic API. It's manual was called the C User Guide hence the name.
>
> The Ada version of RTEMS was removed from the source tree and POSIX came a
> while
> later.
>
> POSIX and the Classic API are both C APIs. The C User manual is now called
> the
> RTEMS Classic API Guide. See:
>
> https://docs.rtems.org/
>
> Chris
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