external declarations of ptrs and arrays

[Bryan Cardoza]

In article <674 at dg.dg.com> hmelman at absolut.rtp.dg.com (Howard Melman) writes:
>I have the file declare.c:
>
>char temp[20]="blah";
>
>I have the file use.c:
...
>extern char *temp;
...
>This causes a core dump.  When I change my extern declaration in use.c to be:
>
>extern char temp[];
>
>the program works fine.  I was under the impression that the two
>declarations were the same.  Help...

No so.  When using *temp, the contents of temp are used, whereas
when using temp[], the address of temp is used.  In M68k assembly
(using the System V/68 assembler syntax) we are talking about the
difference between

	mov.l	temp,%a0

for *temp and

	mov.l	&temp,%a0

for temp[].  Sure, you can often use the two the same way in your
C programs, but remember, we're talking about a storage declaration
here, and pointers and arrays are not the same thing.
-- 
Bryan Cardoza			UUCP: uunet!iconsys!bryan
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