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From: ejkst@cisunx.UUCP (Eric J. Kennedy)
Newsgroups: comp.sys.amiga
Subject: Re:  Struggling through the "C"
Message-ID: <17491@cisunx.UUCP>
Date: 12 Apr 89 02:29:19 GMT
References: <2570@ssc-vax.UUCP> <231@nlgvax.UUCP> <6542@cbmvax.UUCP>
Reply-To: ejkst@unix.cis.pittsburgh.edu (Eric J. Kennedy)
Organization: Univ. of Pittsburgh, Comp & Info Sys
Lines: 45

In article <6542@cbmvax.UUCP> kevin@cbmvax.UUCP (Kevin Klop) writes:
>Actually, there is a difference between 'a' in the following two
>declarations:
>
>char a[80];
>char *a;

[explanation and demonstration deleted]

I've always thought that there was another difference besides what you
described--one with more important and practical consequences.  I've
often had trouble with this stuff, being an inexperienced C programmer,
so somebody please tell me if this isn't right!  I just didn't see
anything like this addressed in Kevin's article.

It has been my understanding that "char *a;" gives you a pointer,
(pointing to some arbitrary place), while "char a[80];" actually
allocates 80 bytes of memory, and gives you a pointer to it, one that
you can't (or shouldn't) change.

Thus,

char a[80];
main()
{
  strcpy(a,"hello");
}

is okay, while

char *a;
main()
{
  strcpy(a,"hello");
}

will cause real problems, like overwriting your program or another task
with the word "hello".  You'd have to do a malloc() or AllocMem() or
something to have a safe place to put the "hello".

So, is this right, or is my feeling of confusion justified?

-- 
Eric Kennedy
ejkst@cisunx.UUCP