Xref: utzoo comp.lang.c:12547 comp.lang.fortran:1087
Path: utzoo!attcan!uunet!sdrc!scjones
From: scjones@sdrc.UUCP (Larry Jones)
Newsgroups: comp.lang.c,comp.lang.fortran
Subject: Re: C associativity rules
Keywords: associativity, expressions
Message-ID: <382@sdrc.UUCP>
Date: 13 Sep 88 22:42:04 GMT
References: <412@marob.MASA.COM>
Organization: Structural Dynamics Research Corp., Cincinnati
Lines: 22

In article <412@marob.MASA.COM>, samperi@marob.MASA.COM (Dominick Samperi) writes:
> Does K&R C or the new ANSI C permit the compiler to evaluate an expression
> like a+b+c in any order it pleases, rather than in the strict left-to-right
> order (a+b)+c ? I've always assumed that a strict left-to-right order would
> be used, as is the case for relational expressions like the one in the
> following.
> 		while(i != -1 && a[i] != k)
> 			whatever ;

K&R has always allowed the compiler to evaluate in any order at all (even in
the presence of parentheses).  The only operators which are guaranteed to
evaluate left-to-right are "&&", "||", and ",".  Ansi now requires compilers
to evaluate "as if" they honored parentheses, and perhaps even associativity
in unparenthesized expressions (there's still some debate as to exactly what
the wording says).

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