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To: Neo Liu <diabloneo@gmail.com>
Cc: SystemTap <systemtap@sourceware.org>
Subject: Re: operator precedence differs from C language
References: <p2p861674c01003311936nef74996ckcf3febde43d4e85b@mail.gmail.com>
From: fche@redhat.com (Frank Ch. Eigler)
Date: Thu, 01 Apr 2010 16:30:00 -0000
In-Reply-To: <p2p861674c01003311936nef74996ckcf3febde43d4e85b@mail.gmail.com> (Neo Liu's message of "Thu, 1 Apr 2010 10:36:54 +0800")
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Neo Liu <diabloneo@gmail.com> writes:

> I found that the operator precedence of "&" and "==" differed from C
> language. Take a look at the following statements.
>     if ($flags & 07 == 0) { ... }

Actually, I think we do it the same way C does.  Comparison operators
such as "==" have higher precedence.

% cat foo.c
int main () {
  printf("%d\n", 0xf0 & 0xff == 0);
}
% cat foo.stp
probe begin {printf("%d\n", 0xf0 & 0xff == 0); exit()}

Both these print 0 for == or !=.


- FChE