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Path: utzoo!mnetor!seismo!rutgers!mit-eddie!genrad!decvax!ucbvax!ucdavis!nagel@iris.ucdavis.edu (Mark Nagel)
From: nagel@iris.ucdavis.edu (Mark Nagel)
Newsgroups: comp.lang.c
Subject: Re: COMMA separated expresses
Message-ID: <595@ucdavis.UUCP>
Date: Thu, 25-Jun-87 12:38:27 EDT
Article-I.D.: ucdavis.595
Posted: Thu Jun 25 12:38:27 1987
Date-Received: Sat, 27-Jun-87 02:28:36 EDT
References: <1601@oliveb.UUCP>
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Reply-To: nagel@iris.UUCP (Mark Nagel)
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Organization: University of California, Davis
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In article <1601@oliveb.UUCP> dchen@oliveb.UUCP (Dennis T. Chen) writes:
>Why did my C compiler(came with 4.3bsd) complaint the "syntax error"
>with the following COMMA separated express statements in a function:
>
>funct()
>{
>	int i = 0;
>
>	if ( i == 0 )
>		printf("A\n"), return; /* syntax error here */
>	printf("END\n");
>}
>
>But it works fine with
>
>	if ( i == 0 )
>		printf("A\n"), exit(1);	/* compile OK */
>
>Could someone point this out ? It seems to me that rule 7.15 Comma
>operator, on page 192 of C Programming Language doesn't state much
>on this.
>
>Dennis Chen

The first example has an expression (a function) comma separated with a
statement.  The comma operator is supposed to evaluate to the rightmost
expression.  Since the rightmost item here is not an expression, you get
the problem.  The second example illustrates this -- exit is a function,
thus an expression.




--- Mark Nagel
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