Re: Why C++ is vastly superior to C

From:
"Balog Pal" <pasa@lib.hu>
Newsgroups:
comp.lang.c++
Date:
Sun, 22 May 2011 02:59:07 +0200
Message-ID:
<ir9n4v$svo$1@news.ett.com.ua>
"Dombo" <dombo@disposable.invalid>

I never looked seriously at C99 but the last time I looked at C it didn't
have destructors, exceptions, templates or other constructs that can
generate surprising amounts of code if one is not careful.


For some reason claims about amount of code in forums generally come from
people who never bothered to look at assy. Just like the famous priest back
in middle age who knew better that Jupiter can not have moons. Please do
some experiments then come back with results, and we may have a fruitful
discussion.

By design certainly, that was the point -- you write code using abstract
types like int, short, pointers, "arrays", and the approppriate assembly
code is generated for the platform.

Can you tell what machine instructions you will get from a C source? For
some level, yes: if you know the semantics.

But the very same is true for C++.


In the strict sense that can be said for just about any language, but for
some programming languages it is easier to predict what code will
generated than others. There are many shades of gray between black and
white.


Probably so, but I keep the claim that destructor code hardly surprises any
competent C programmer.
With implicit converting ctors and operators you indeed can create a mess,
but the base guidelines say not to use them. And when used they are
hopefully well designed. (And deliberate bad design is not worth
discussing, as C has too many elements that are can be broken.)

The point "Nobody" was making is that C being such a low level language
the translation from source code to assembly is relatively
straightforward, so it is easier for a programmer to predict what kind of
code and how much code the compiler will produce by just looking at the
source code.


I never had problem predicting the code in either language. My experience
really show no practical difference. I mean if said prediction happens in
the correct context, as comparing it to the *necessary* code to have a
desired behavior.

In many cases this is a matter of no concern, but in small embedded
systems where every cycle counts and the amount memory is expressed in
Kilobytes or less rather than Mega- or Gigabytes you don't want to have
too much between you and the bare metal.


Another interesting observation from forums, that claims about embedded
systems too often come from people never working on any. I for example did
embedded stuff in both languages. Exceptions are normally turned off, while
dtors and templates are welcome. And they create the same code you would by
hand. And when you're hit by a case you need to do assembly, it is the
same in C.

In some cases C might be the right compromise between assembly and C++.


The only cases I experienced were "no C++ compiler" and "C++ compiler way
too expensive".

When Bjarne created C++ the design foundation had both "C compatibility" and
"no pay for what is not used". And those fairly succeeded.

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