Variable-length string at end of structure

[John Bruner]

I've used this trick in a number of programs, usually for symbol
tables and the like.  The last element of my structures is
always a one-element character array.

Several years ago, when I was first maintaining APL\11 at Purdue/EE,
I had to transport it from V6 PDP-11's running the photo7 C
compiler to a VAX running 32/V.  The program had compiled without
a hitch on Ritchie's compiler, but the pcc-derived VAX compiler
produced roughly 800 error messages.  One of them related to the
"item" structure that APL was using.  The structure was defined as:

	struct item
	{
		char	rank;
		char	type;
		int	size;
		int	index;
		data	*datap;
		int	dim[0];
	};

(This structure appears at the beginning of each data item.  Space is
allocated for the structure, "rank" elements of the array "dim", and
"size" double-precision floating-point numbers which specify the data.)

Ritchie's compiler accepted this (and perhaps still does today), but
"pcc" complained about the zero-element array "dim".  I had to recode
it so that "dim" was declared with a non-zero number of dimensions
and then fudge the allocation so that the same amount of space was
allocated.
--
  John Bruner (S-1 Project, Lawrence Livermore National Laboratory)
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-- 
  John Bruner (S-1 Project, Lawrence Livermore National Laboratory)
  MILNET: jdb at mordor.ARPA [jdb at s1-c]	(415) 422-0758
  UUCP: ...!ucbvax!dual!mordor!jdb 	...!decvax!decwrl!mordor!jdb