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From: franka@mmintl.UUCP (Frank Adams)
Newsgroups: net.lang.c++
Subject: Re: for != while
Message-ID: <1793@mmintl.UUCP>
Date: Mon, 8-Sep-86 18:38:37 EDT
Article-I.D.: mmintl.1793
Posted: Mon Sep  8 18:38:37 1986
Date-Received: Sun, 14-Sep-86 03:31:37 EDT
References: <749@tekla.UUCP>
Reply-To: franka@mmintl.UUCP (Frank Adams)
Organization: Multimate International, E. Hartford, CT
Lines: 46

In article <749@tekla.UUCP> in net.lang.c dant@tekla.UUCP writes:
>>>In article <86900030@haddock> karl@haddock writes:
>>>>It's well known that the equivalence between for and while breaks down if
>>>>there's a "continue" statement.  Here's another case I just discovered:
>>>>
>>>>main() {
>>>>	char *foo = "outer";
>>>>	for (;; printf(foo),exit(0)) {
>>>>		char *foo = "inner";
>>>>	}
>>>>}
>>>>
>>>>This prints "outer" (vax SVR2 compiler), though the for-while equivalence
>>>>might lead one to expect "inner".
>the ... above is correct.  The
>equivalence of the ... example is this:
>
>main() {
>	char *foo = "outer";
>	while () { 
>		{
>			char *foo = "inner";
>		}
>	printf(foo),exit(0));
>	}
>}
>
>The *foo = "inner" applies only within the inner braces (which 
>delineate the statement).  The printf(foo) goes outside those braces.

This is fine as far as C goes.  In C++, one may instead write 

main() {
	char *foo = "outer";
	for (;; printf(foo),exit(0)) char *foo = "inner";
}

which should, in fact, print "inner"[1].  I don't currently have accesss to
the C++ processor; does anyone know whether these two examples in fact work
correctly for it?

Frank Adams                           ihnp4!philabs!pwa-b!mmintl!franka
Multimate International    52 Oakland Ave North    E. Hartford, CT 06108

[1] Actually, my example may be an illegal multiple definition of foo.  In
this case, try it with the "outer" declaration removed.