Various Topics on C++

..ur..

http://www.sys-con.com/story/print.cfm?storyid=45250

Any comments?

Thanks
Gaurav

..rn.. ..is..

"Gaurav" <gaurav_7_7@yahoo.com> schrieb im Newsbeitrag
news:7113e26f.0406152345.2f01b86c@posting.google.c om...
> http://www.sys-con.com/story/print.cfm?storyid=45250
>
> Any comments?
>
> Thanks
> Gaurav

Huhuhu-hahaha...
Java faster ...haha... than C++ ...ha-hahaha...

First of. If you take a close look at the language features you will
see that you can do everything you do in Java in C++ but not vice
versa. Next, if you "optimize" code by the compiler it can't become
any better than the ****py C++ you provide. So, if you want to really
compare the 2, you should get 2 professional prograamers for each
language and let each one do the way their language requires doing.
Next, gcc 3.3 is not really a good optimizing compiler. Better than
2.95, but not as good as say the intel or the codewarrior compilers.
But for a wednesday mornig, a good joke, thank you.

-Gernot

..rc.. ..licins..

The code in Java cannot be any faster than in C++, because with C++ the
generated code is practically 100% optimal, provided that the program is
written with it in mind, and the compiler is good. And there are good
compilers out there.

Best regards,
Marcin

..m_usen..

On 16 Jun 2004 00:45:02 -0700, gaurav_7_7@yahoo.com (Gaurav) wrote:

>http://www.sys-con.com/story/print.cfm?storyid=45250
>
>Any comments?

Whenever I look at inter-language benchmarks in detail, I always find
a flaw in the benchmarking for one language or the other (and often
both), generally based on the author's bias (they generally have
greater expertese in one language than the other).

In the benchmarks you've posted, the compiler options provided to GCC
are sub-optimal, and no functions seem to have been declared inline.
For example, many of the tests would benefit from loop unrolling,
which only happens on -O3 I think. Some of the benchmarks are also
highly synthetic (they don't really do anything except try to bombard
a particular language feature in a way that never happens in a real
program). It's better to set a required output for the input, and then
let the program achieve that output however it wishes to, balancing
code clarity with optimization.

Incidently, I got the fibonacci test down to around 0.1 seconds using
this simple code:

unsigned long fib(unsigned long n) {
unsigned long last = 1;
unsigned long current = 1;
for (unsigned long i = 2; i <= n; ++i)
{
unsigned long newCurrent = last + current;
last = current;
current = newCurrent;
}
return current;
}

Tom
--
C++ FAQ: http://www.parashift.com/c++-faq-lite/
C FAQ: http://www.eskimo.com/~scs/C-faq/top.html

..ni.. ..ankenstein..

Gaurav wrote:

> http://www.sys-con.com/story/print.cfm?storyid=45250
>
> Any comments?

LoL, the guy who wrote that knows absolutely nothing about benchmarking.

br
db

..nu.. ..pilews..

Gaurav wrote:
> http://www.sys-con.com/story/print.cfm?storyid=45250
>
> Any comments?
>

Those tests expose one regularity - the examples where OS support is
extensively used are slower than those where the entire code in
performed in process space. Performance of the former suffers from
user/kernel mode switching and if it is done at least once per loop
iteration the impact must be pretty visible.

So all C++ examples with extensive heap or stack (function calls) memory
allocation must be slower than corresponding Java examples where similar
functionality is performed by the JVM directly in the user process space
(Fibonacci, hash, object creation).

Of course if one is ready to pay with slower startup and bigger memory
consumption then he/she may can have the same in C++ using inlining,
memory pool and other commonly used techniques.

When such handicaps are not introduced (nested loop, random numbers) C++
performs faster as expected.

One thing surprised me. For the reason described above I expected the
method call example to be slower in any case in C++ than in Java, then
after looking at the code it appeared that all member functions were
coded inline and at least some of them were optimized away by the
compiler. So this test does not fulfil its goal. The other ones also
introduce some unnecessary temporary variables etc. and should not be
used as representative C++ code.


Regards,
J****z

.... ..rris..

"Gaurav" <gaurav_7_7@yahoo.com> wrote in message
news:7113e26f.0406152345.2f01b86c@posting.google.c om...
> http://www.sys-con.com/story/print.cfm?storyid=45250
>
> Any comments?
>

I was recently part of a team that rewrote an largish C++ app in Java. No
question that for this application the Java version was slower than the C++
version. No doubt the Java version had some advantages (platform
independence for instance) but it was slower and noticeably so.

john

..r.. ..ve..

Gaurav wrote:
> http://www.sys-con.com/story/print.cfm?storyid=45250
>
> Any comments?
>

In general, you can find arguments to many unfounded things. Weather
this is correct (which I doubt) or not is irrelevant most of the time.

Don't worry about it unless you need to.

Barely related question.

How many of you guys actually work on projects in which performance is
critical? (Something written in Java is unacceptable)

I see value in both languages, however, it appears as though many people
immediately dismiss Java, regardless of the scope and requirements of
the project.

JLR

..lent.. ..homir..

> How many of you guys actually work on projects in which performance is
> critical? (Something written in Java is unacceptable)

When you write a conventional user application for a multitasking system,
your program should accomplish its tasks as fast as possible. Therefore, we
are commited to deliver the fastest software ever. 0.01ms vs. 0.1ms responce
on user button c**** is much more important for us as opposed to development
time. Therefore, we write huge number of code lines and ignore impressing
IDEs like Intellij Idea and go on wasting our time and writing unreliable
code in order to deliver the best performance. Slow C++ compiler does lots
of things for us including and compiling huge files.

..r.. ..rinki.. ..ff.. .. ..e ..¬ƒceâ€..

Gernot Frisch wrote:

> ✄
> you will see that you can do everything you do in Java in C++ but not viceversa.

So there are something that may be do in C++ and not in Java?
Interesting...

Please give me your curriculum, so I can hire you in my company!

- Dario