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From: Keith Thompson <Keith.S.Thompson+u@gmail.com>
Newsgroups: comp.lang.c
Subject: Re: Beginner....Decimal/Octal converter help
Date: Tue, 13 Sep 2022 11:48:48 -0700
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David Brown <david.brown@hesbynett.no> writes:
[...]
> While thinking about newer C features, I have found another challenge
> with using multiple different sometimes incompatible aliases for
> integer types - _Generic.  I don't know if you've used _Generic much,
> but it can sometimes be useful.  Here is a small example :
>
> 	#include <stdint.h>
> 	#include <inttypes.h>
> 	#include <stdio.h>
>
> 	#define print_var(_x) \
> 	    do { \
> 	        printf("Var " # _x  " = "); \
> 	        printf( \
> 	            _Generic(_x, \
> 	                uint8_t : "0x%02" PRIx8, \
> 	                uint16_t : "0x%04" PRIx16, \
> 	                uint32_t : "0x%08" PRIx32, \
> 	                uint64_t : "0x%016" PRIx64), \
> 	            _x); \
> 	        printf("\n"); \
> 	    } while (0);

I'd use the predefined types unsigned char, unsigned short, et al rather
than the uintN_t types.  For example, if uint32_t is unsigned int and
uint64_t is unsigned long long, then passing an unsigned long argument
is an error.  Using the predefined types guarantees that you'll cover
all the integer types.  You can use sizeof to determine the number of
digits.

Except that it all breaks down if some of the types in <stdint.h> are
defined as extended integer types.  There's no good way for a _Generic
expression to cover all the integer types if the implementation supports
extended integer types.  (Then again, I'm not aware of any
implementations that do so.)

[...]

-- 
Keith Thompson (The_Other_Keith) Keith.S.Thompson+u@gmail.com
Working, but not speaking, for Philips
void Void(void) { Void(); } /* The recursive call of the void */