increment casted void pointer -- ANSI?

[Stephen R. van den Berg]

Suppose I have the following (silly example, I know :-) program:

#include <stdio.h>

main(){static char s[]="abcd";void*p;int a,b;
 p=s;
 a=*(char*)p;
 b=*++(char*)p;
 *--(char*)p=b;
 *++(char*)p=a;
 puts(s);
 return 0;}

Now, you tell me if this is ANSI or K&R or neither, and if it's not ANSI,
how do I do it in ANSI then?

I always thought this was ANSI code, but there seems to be some
compiler on an IBM RT that says otherwise.

Thanks.
--
Sincerely,                 berg at marvin.e17.physik.tu-muenchen.de
           Stephen R. van den Berg.
"I code it in 5 min, optimize it in 90 min, because it's so well optimized:
it runs in only 5 min.  Actually, most of the time I optimize programs."