OT: Requesting C advice

[Mike McCarty]

Michael Hennebry wrote:
> On Wed, 23 May 2007, George Arseneault wrote:
> 
> 
>>Now the bad news... C, C++, gnu, several variations on
>>the ISO; not to mention all the libraries, etc.  And,
>>to top it off, some of the stuff in the book just
>>doesn't work.  (A program to demonstrate the various
>>types of integer variables and how to display them
>>with printf(), failed to show any difference with any
>>arguments I could find.)
> 
> 
> Should they have produced different results?

On big-endian machines, they can. For example, with two's complement
arithmetic on a big-endian machine,

printf("%d\n",-2);

does not result in

-2

but likely in

-65535

or

-2147483647


> Printing (int)sizeof(typename) will distinguish some types.
> Note that short, int and long usually only have two distinct sizes.
> It's allowed, but rare, for all the arithmetic types to have size 1.

Note that what you suggest works because sizeof(.) for integer
types is going to be a small number. The only portable means
of displaying an unsigned integer of unknown size is

printf("Thing = %ul\n",(unsigned long int)Thing);

For "rare" read "no known implementation". Since long int
is required to be at least 32 bits, that would require
that char be at least 32 bits.

Mike
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