Re: C bug of the day

[kanze@gabi-soft.fr]

James Rogers <jimmaureenrogers@att.net> wrote in message
news:<Xns9398BD1E07E3Ejimmaureenrogers@204.127.36.1>...
 > "Andrei Alexandrescu" <SeeWebsiteForEmail@moderncppdesign.com> wrote
 > in news:bc9h7j$gm42t$1@ID-14036.news.dfncis.de:

 >  > I was mentioning that just to mention a simple language design
 >  > decision that's a no-brainer to implement, yet which imho has a
 >  > great impact because of the psychological issue you mentioned. The
 >  > others are also important, but not as trivial to implement and
 >  > support without making performance tradeoffs.

 > I am sorry. I misunderstood. I thought you were being sarcastic.  If
 > your suggestion was adopted, how would it affect existing programs?
 > For that matter, why would you ever *want* uninitialized variables?
 > Another way to ask that is when is initialization a bad thing?

For the same reason you might want to access an array without a bounds
check, I guess: performance.  If you know that the initialization will
take place before the variable is used, and you have a performance
problem, initialization is a loss of time.

I imagine that such cases would be rare.  But then, I imagine that they
would be exceedingly rare for bounds checking, too.

FWIW: I've seen numeric benchmarks where Java (with bounds checking)
runs faster than C++ (without).  The reason is simple: the Java compiler
is able to hoist the bounds checking out of the tight loops, or even
eliminate it entirely.  And it doesn't have to deal with all of the
aliasing issues due to the language supporting pointer arithmetic.  It's
probably worth pointing out that C's pointer arithmetic is not only
dangerous, and a significant source of errors, but it also makes
programs run slower.

--
James Kanze             GABI Software             mailto:kanze@gabi-soft.fr
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