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From: sweetmr@SCT60A.SUNYCT.EDU (michael sweet)
Newsgroups: comp.sys.sgi
Subject: Re: C compiler weirdness?
Message-ID: <4597.on.Mon,.8.Apr.91.18:32:50.EDT.@sct60a.sunyct.edu>
Date: 8 Apr 91 22:32:50 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 36


> only to discover that the C compiler does not increment pc until after the
> function call returns in the following statement:
>           (*(*pc++))();

The time of increment/decrement IS compiler dependent.  The only constraint
with ++/-- is that '++i' increments 'i' before using that value, and 'i--'
after the valuye is used.  This causes MUCH heartache in the above code and
the following (which I see all too often, and should NEVER be used if you want
to port code to a different machine!)

 while (*s)
  *s = *++s;

(or similar...)  What the person probably wants to do is delete a character
from a string (starting at 's'...).  The idiot assumes that '*s' is evaluated
for the assignment FIRST, and then 's' is incremented.  A nicer way (which
will get optimized away anyway) and MORE READABLE way is:

 while (*s)
  {
   *s = *(s+1);
   s++;
  };


The KISS philosophy is best when coding in C (keeps you from going crazy!)

 -Mike Sweet

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