Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!cs.utexas.edu!helios!stat!john
From: john@stat.tamu.edu (John S. Price)
Newsgroups: comp.lang.c
Subject: Re: Assignment of void pointer variable
Keywords: Can I do it in one step?
Message-ID: <4265@helios.TAMU.EDU>
Date: 18 Feb 90 11:55:48 GMT
References: <19390@grebyn.com>
Sender: usenet@helios.TAMU.EDU
Reply-To: john@stat.tamu.edu (John S. Price)
Organization: Texas A&M University
Lines: 38

In article <19390@grebyn.com> jmbj@grebyn.com (Jim Bittman) writes:
>This works in C, but I'd like to combine the last two lines...
>  void *varptr[10];
>  int  *intptr;
>  int  myint;
>  intptr = varptr[5]; 
>  myint = *intptr;
>Goal:  myint = (int) *varptr[5];  /* doesn't work, it's what I want! */
>Post or mail suggestions, Thanks for the help!
>Jim Bittman
>jmbj@grebyn.com

Umm... I believe this will work.

myint = *(int *)varptr[5];

The reason:
varptr is declared to be a void pointer, so you have
to tell the compiler what you want it to be "looking"
at when you dereference it.  The (int *) cast tells the
compiler that the next pointer is a pointer to an integer,
and the outer dereference takes the integer at that location.

The reason yours didn't work is this:
myint = (int) *varptr[5];

You have a void pointer, defreference it,
and cast the result to an integer.  This,
I assume, isn't what you wanted.

hope this helps, and I might be totally rambling, for
it is quite early in the morning...


--------------------------------------------------------------------------
John Price                   |   It infuriates me to be wrong
john@stat.tamu.edu           |   when I know I'm right....
--------------------------------------------------------------------------