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From: firth@sei.cmu.edu (Robert Firth)
Newsgroups: comp.lang.c
Subject: Re: swaps with arrays
Message-ID: <2590@aw.sei.cmu.edu>
Date: Tue, 22-Sep-87 13:19:20 EDT
Article-I.D.: aw.2590
Posted: Tue Sep 22 13:19:20 1987
Date-Received: Thu, 24-Sep-87 06:02:01 EDT
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In article <768@sugar.UUCP> peter@sugar.UUCP (Peter da Silva) writes:
>> It is true that the semantics of the assignment of arrays is obvious and
>> straightforward (I think -- there may be some traps hiding there somewhere).

>Snap! The size of an array is not always known to the compiler.
>
>For example:
>
>extern char *sys_errlist[];

But neither is the size of an array in Algol-60, Algol-68, Ada, or most
other languages that support soem form of array assignment.  There would
surely be no difficulty is accessing a runtime descriptor that gave the
array size?

In fact, since in C all declared arrays have a static size, one could
simply generate a hidden external name "sys_errlist_size" or whatever,
resolved at link time, and use that.  No harder than resolving the
array name at link time.  On a Vax-11, for instance,

	.GLOBAL sys_errlist_size, sys_errlist
	MOVC3 #sys_errlist_size, G^sys_errlist, copy_of_sys_errlist

would do the job.