Re: "A diagram of C23 basic types"

On Tue, 8 Apr 2025 16:47:07 +0100
bart <bc@freeuk.com> wrote:

On 08/04/2025 15:57, David Brown wrote:

On 08/04/2025 15:32, bart wrote: 

On 05/04/2025 18:56, Philipp Klaus Krause wrote: 

Am 02.04.25 um 11:57 schrieb bart: 

* Where are the fixed-width types from stdint.h? 

>
Same as for size_t, etc: They don't exist. Those are not separate
types, just typedefs to some other types. E.g. uint16_t could be
typedef'ed to unsigned int.
 

>
This is the point I made a few weeks back, but others insisted
they were part of C:
>
>
Me: 
 >> stdint.h et al are just ungainly bolt-ons, not fully supported
by the >> language. 
>
Keith Thompson:
 
 > No, they're fully supported by the language.  They've been in
the ISO > standard since 1999.
 > 
>
This is an exchange posted on 20-Mar-2025 at 19:10 GMT (header
shows 'Thu, 20 Mar 2025 12:10:22 -0700')
>
Clearly, they're not quite as fully supported as short, int etc;
they are usually just aliases. But that needn't stop them being
shown on such a chart. 

 
Standard aliases are part of the language standard, and therefore
standard and fully supported parts of the language.
 

 
So, should they have been on that chart?
 
 > and fully supported parts of the language. 
 
Differences between 'unsigned long long int' and 'uint64_t' up to C23:
 
                          uint64_t   unsigned long long int
 
Works without header     No         Yes
 
Literal suffix           No         Yes (ULL etc)
 
Dedicated printf format  No         Yes (%llu)
 
Dedicated scanf format   No         Yes (whatever that might be)
 
sizeof() might not be 8  No         Maybe

I don't think that 'No' above is correct.
Take, for example, ADI SHARC DSPs. Traditionally, sizeof(uint64_t) was
2.
I looked into the latest manual and see that now their compiler have
an option -char-size-8 and with this option sizeof(uint64_t)=8. But
this option is available only for those members of SHARC family that
have HW support for byte addressing. Even for those, -char-size-8 is
not a default.

 
Reserved word[1]         No         Yes
 
Outside lexical scope[2] No         Yes
 
Incompatible with
  unsigned long int       No         Yes
>

I don't understand why you say 'No'. AFAIK, on all existing systems
except 64-bit Unixen the answer is 'Yes'.

 
[1] Maybe _t names are reserved, but this:
 
   typedef struct {int x,y;} uint64_t;
 
compiles cleanly with:
 
   gcc -std=c23 -Wall -Wextra -pedantic
 
This means that they could legally be used for any user-defined types.
 
[2] This is possible with uint64_t:
 
   #include <stdint.h>
 
   int main() {
       typedef struct {int x,y;} uint64_t;
   }
 
You can shadow the names from stdint.h.
 
So I'd dispute they are as fully supported and 'special' as built-in
types.