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From: karl@haddock.UUCP
Newsgroups: comp.lang.c
Subject: Array primitives (was: *\"LDA\" ok?)
Message-ID: <1036@haddock.ISC.COM>
Date: Tue, 1-Sep-87 12:45:08 EDT
Article-I.D.: haddock.1036
Posted: Tue Sep  1 12:45:08 1987
Date-Received: Wed, 2-Sep-87 07:22:39 EDT
References: <8877@brl-adm.ARPA> <8088@mimsy.UUCP> <87@splut.UUCP> <2211@emory.uucp>
Reply-To: karl@haddock.ima.isc.com (Karl Heuer)
Organization: Interactive Systems, Boston
Lines: 29

In article <2211@emory.uucp> arnold@emory.UUCP (Arnold D. Robbins {EUCC}) writes:
>[Suggests a new symbol "`" to represent arrays manipulated by value]

If ANSI can be convinced not to repeat a certain K&R mistake, most of the
cases you describe could be written without the new punctuator.

To pass an array by value and/or return one:
	char foo(char arg[INSIZE])[OUTSIZE];
Once the prototype is in scope, "a1 = foo(a2)" can be interpreted properly.
The array copy operation, "a1 = a2", is best handled by amending the array-to-
-pointer conversion rule so that it does not attempt to convert "a2" in this
context.  (Note that this depends on "a1" being an array, not a pointer.)

As has already been pointed out, most array manipulation in C at present is
done via pointers instead.  For fixed-length arrays this is not a problem;
after "p = (int *)malloc(100 * sizeof(int));" one could copy the entire array
by naming it "*(int (*)[100])p".  (Better yet, one could make p a pointer to
array in the first place: "p = (int (*)[100])malloc(sizeof(int[100]));" ...
"*p".)

Variable-sized arrays are trickier.  I don't think it's appropriate to make
"array of char" a magic synonym for "NUL-terminated string"; that partially
solves one special case rather than the general problem.  It smacks of PASCAL
kludgery.

The general problem of variable-sized arrays probably does require a new
punctuator.  I have an idea on this, too, but it needs more refinement.

Karl W. Z. Heuer (ima!haddock!karl or karl@haddock.isc.com), The Walking Lint