Path: utzoo!mnetor!uunet!seismo!sundc!pitstop!sun!decwrl!decvax!purdue!umd5!mimsy!chris
From: chris@mimsy.UUCP (Chris Torek)
Newsgroups: comp.lang.c
Subject: lvalues (was Re: Question about type casting)
Message-ID: <10227@mimsy.UUCP>
Date: 17 Jan 88 23:06:14 GMT
References: <546@xyzzy.UUCP> <5080012@hpfcdc.HP.COM>
Organization: U of Maryland, Dept. of Computer Science, Coll. Pk., MD 20742
Lines: 22

In some article somewhere, someone writes:
>>I believe that Standard C does not allow type casting on the left of the 
>>= sign.

In article <5080012@hpfcdc.HP.COM> boemker@hpfcdc.HP.COM (Tim Boemker) writes:
>How about this:
>
>int i; char *c;
>c = (char *) &i;
>* (int *) c = 0;

It is not portable, but it is legal.

The result of a cast is an `rvalue' (R for Right: or in other words,
the kind of thing one finds on the right hand side of an assignment).
Assignments may be made only to `lvalues' (L for Left: the kind of
thing found on the left hand side of an assignment).  The C indirection
operator `*' takes an rvalue and yeilds an lvalue, hence the result
of `* (int *) c' is an lvalue.
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7163)
Domain:	chris@mimsy.umd.edu	Path:	uunet!mimsy!chris