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From: ballou@brahms (Kenneth R. Ballou)
Newsgroups: comp.lang.c
Subject: Re: "exit 0;"  - or -  "exit (0);" ?
Message-ID: <331@cartan.Berkeley.EDU>
Date: Mon, 17-Nov-86 15:54:31 EST
Article-I.D.: cartan.331
Posted: Mon Nov 17 15:54:31 1986
Date-Received: Mon, 17-Nov-86 22:24:14 EST
References: <1512@batcomputer.tn.cornell.edu>
Sender: daemon@cartan.Berkeley.EDU
Reply-To: ballou@brahms (Kenneth R. Ballou)
Distribution: net
Organization: Math Dept. UC Berkeley
Lines: 45

In article <1512@batcomputer.tn.cornell.edu> braner@batcomputer.UUCP (braner) writes:
>While K&R explicitly say that exit() is a function, I commonly see
>the parens dropped.  Is that "legal"? Does it work on existing compilers?

	Note that 'exit' is not a reserved word in (K&R) C.  Therefore, the 
compiler should reject the construct  exit 0;  on at least two grounds.  If 
you have not previously declared exit to be a function, it should complain 
that exit is an undefined variable.  Then it should complain because you have
two rvalues with no operator in between.

>And while I am asking:  how's "if (foo) {...}" vs. "if foo {...}" ?
>(in the case where "foo" is a variable, say an int used as a flag.)

	Perhaps I should be charitable and assume that you simply do not have 
access to either K&R or Harbison and Steele to look this up yourself, although
I find it hard to believe that Cornell does not have libraries.

K&R, page 201:  Near the bottom of the page we see

9.3 Conditional statement
	The two forms of the conditional statement are

		if ( expression ) statement
		if ( expression ) statement else statement

Harbison and Steele, page 202:  In the section titled "Conditional Statement,"
we have:

	conditional-statement ::= if-statement | if-else-statement
	if-statement ::= if '(' expression ')' statement
	if-else-statement ::=
		if '(' expression ')' statement else statement

	This very same information can be found on page 331 of H&S in the last
three lines. For a more rigorous description, you might turn to page 339 in
Appendix C, "LALR(1) grammar for C".

	I think I have made my point.  People have written books which specify
the grammar of C.  I sometimes wonder why they go through all the bother ...

--------
Kenneth R. Ballou		...!ucbvax!brahms!ballou
Department of Mathematics	ballou@brahms.berkeley.edu
University of California
Berkeley, California  94720