C++: Is it a powerful language?

[Roberto Dias]

Why is C++ a powerful language? Does it fit for engineering purpose? I
mean, for doing matrices manipulation, numerical computing, solving
equations, and, eventually, for file streaming. Should I migrate
direct for C++, by-passing the C?

Thanks,

[Ron Natalie]

Roberto Dias wrote:

Why is C++ a powerful language?
Yes.
Does it fit for engineering purpose? I
mean, for doing matrices manipulation, numerical computing, solving
equations,
You'll need a good math library, the standard libraries for C and C++
are notably lacking in rigorous numerical functions (like matrices,
etc..) but there are some out there.
eventually, for file streaming.
This sort of operatal application is what C and C++ excel at.
Should I migrate
direct for C++, by-passing the C?

If you're working on an implementation that has a good C++ compiler]
existant (and most "general purpose" processosrs do), I would say yes.
There's no real advantage of C and a lot of strong reasons to do C++.
The performance is going to be the same, but the code will be easier
and more maintainable in C++.

The only argument for C is for certain embedded implementations where
only a minimal C implentation is practica.

[Victor Bazarov]

Roberto Dias wrote:

Why is C++ a powerful language?
Because it was designed as such.
Does it fit for engineering purpose?
It does. Or, rather, it is. Whatever.
I
mean, for doing matrices manipulation, numerical computing, solving
equations, and, eventually, for file streaming. Should I migrate
direct for C++, by-passing the C?

I don't know if you should _migrate_ (from where?), but if you do migrate,
you do not need to study C as a pre-requisite. Knowing the differences
between them helps, and knowing C as a language can be useful sometimes,
but you can definitely pick that all up along the migration path.

V

[Gernot Frisch]

> Why is C++ a powerful language?

It's getting compiled to "C" and not much is getting added. (Pointers
to functions of structures, which are classes in C++ ...)

Does it fit for engineering purpose? I
mean, for doing matrices manipulation, numerical computing, solving
equations, and, eventually, for file streaming. Should I migrate
direct for C++, by-passing the C?

lol. You can write C++ programs, and if speed is a problem, you can
use C functions in your classes like:

// esternal "C" compiling of this function
extern"C"
{
DoExternFastMat h()
{}
}

// C++ class wrapper that calls a fast function
class A
{

inline DoSomeFastMath( )
{
DoExternFastMat h();
}
}

You can write crappy C++ code, you can do this in C, in FORTRAN and in
ASM.
If you need samples about slow and buggy, code, let me know. I've got
lot's if it ;)

-Gernot

[Victor Bazarov]

Gernot Frisch wrote:

Why is C++ a powerful language?

It's getting compiled to "C"

What are you talking about?
and not much is getting added. (Pointers
to functions of structures, which are classes in C++ ...)

Does it fit for engineering purpose? I
mean, for doing matrices manipulation, numerical computing, solving
equations, and, eventually, for file streaming. Should I migrate
direct for C++, by-passing the C?

lol. You can write C++ programs, and if speed is a problem, you can
use C functions

Why would it be necessary? You seem to have a perverted view of what
makes a program fast.
[...]

[Gernot Frisch]

> I don't know if you should _migrate_ (from where?), but if you do

migrate,
you do not need to study C as a pre-requisite. Knowing the
differences
between them helps, and knowing C as a language can be useful
sometimes,
but you can definitely pick that all up along the migration path.

Indeed, I read the book "Teach yourself "C" in 21 days" (in 5 days)
and there was a small topic about C++ in the end. So, I wrote "C++"
like:
for (int i; ...)
and
class A
{
public:
void foo();
}

until I got a job, doing C++ programming. Where suddenly I had to
reqrite a template list container. It looked so cryptic to me back
then...
If I can give one advice: Start C++ by learning C++. Noothing more,
nothing less. Every other thing you learn dueing your learning process
will spoil your code-style and result in curses when maintaining old
code.

Just my 0.02$,
Gernot

[Gernot Frisch]

"Victor Bazarov" <v.********@com Acast.net> schrieb im Newsbeitrag
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Gernot Frisch wrote:

Why is C++ a powerful language?

It's getting compiled to "C"

What are you talking about?

class A
{
void foo();
}

gets:
struct A
{
void* vtable[];
}
A__foo();
A.vtable[0] = A__foo();

am I wrong??

lol. You can write C++ programs, and if speed is a problem, you can
use C functions

Why would it be necessary? You seem to have a perverted view of
what
makes a program fast.

Well, using class functions will result in a vtable lookup for the
function. It's not much time, but it _is_ time. When programming for
mobile devices some critical sections can be speed up by leaving this.
Not nic style, however - avoid wherever possible.
As said: Most time it's not the language that makes a program slow,
it's the programmer.

[Victor Bazarov]

Gernot Frisch wrote:

"Victor Bazarov" <v.********@com Acast.net> schrieb im Newsbeitrag
news:rI******** ***********@new sread1.mlpsca01 .us.to.verio.ne t...

Gernot Frisch wrote:

Why is C++ a powerful language?
It's getting compiled to "C"
What are you talking about?

class A
{
void foo();
}

;
gets:
struct A
{
void* vtable[];
}
A__foo();
A.vtable[0] = A__foo();

am I wrong??
Hell, yes. What vtable? In fact, in most cases there would be no 'foo'
because the function can never be called -- it's private and the class
has no other members or friends. So, there will be no function _at_all_.

lol. You can write C++ programs, and if speed is a problem, you can
use C functions

Why would it be necessary? You seem to have a perverted view of
what
makes a program fast.

Well, using class functions will result in a vtable lookup for the
function.

No, it won't. I guess it's back to textbooks for you. Or just compile
your program to get an ASM output and analyse it.
It's not much time, but it _is_ time. When programming for
mobile devices some critical sections can be speed up by leaving this.
Not nic style, however - avoid wherever possible.
As said: Most time it's not the language that makes a program slow,
it's the programmer.

<shrug>

[Karl Heinz Buchegger]

Gernot Frisch wrote:

"Victor Bazarov" <v.********@com Acast.net> schrieb im Newsbeitrag
news:rI******** ***********@new sread1.mlpsca01 .us.to.verio.ne t...

Gernot Frisch wrote:

Why is C++ a powerful language?
It's getting compiled to "C"
What are you talking about?

class A
{
void foo();
}

gets:
struct A
{
void* vtable[];
}
A__foo();
A.vtable[0] = A__foo();

am I wrong??

Yes and no.
It could be that way, it need not be that way.
Actually: Nowhere it is written down, that C++ *has to be compiled* to C.
It can be done, it has been done, but most compilers actually don't do it.

lol. You can write C++ programs, and if speed is a problem, you can
use C functions

Why would it be necessary? You seem to have a perverted view of
what
makes a program fast.

Well, using class functions will result in a vtable lookup for the
function. It's not much time, but it _is_ time.

Only in the case of polymorphism (if I assume at the moment that the
compiler is indeed using a vtable for virtual functions). Ordinary
function calls are resolved the same way as C functions would.

But in case of virtual functions: Well, you don't make functions
virtual just for fun. There is a reason for it. And the reason is
polymorphism. Now if you try to implement polymorphism in C (that
is without virtual functions) you end up with something either
very similar to what the C++ compiler does or with something that
is
a) harder to maintain
b) slower then what the C++ compiler can do.

So in case of ordinary function calls there is no difference to C.
In case of polymorphic function calls, C++ can do better then an
average C programmer does. At best C++ and C are on an equal scale,
but C++ is never slower then C.

--
Karl Heinz Buchegger
kb******@gascad .at

[Mike Wahler]

"Gernot Frisch" <[e-mail] > wrote in message
news:35******** *****@individua l.net...

"Victor Bazarov" <v.********@com Acast.net> schrieb im Newsbeitrag
news:rI******** ***********@new sread1.mlpsca01 .us.to.verio.ne t...

Gernot Frisch wrote:

Why is C++ a powerful language?
It's getting compiled to "C"

What are you talking about?

class A
{
void foo();
}

gets:
struct A
{
void* vtable[];
}
A__foo();
A.vtable[0] = A__foo();

am I wrong??

lol. You can write C++ programs, and if speed is a problem, you can
use C functions

Why would it be necessary? You seem to have a perverted view of
what
makes a program fast.

Well, using class functions will result in a vtable lookup for the
function. It's not much time, but it _is_ time. When programming for
mobile devices some critical sections can be speed up by leaving this.
Not nic style, however - avoid wherever possible.
As said: Most time it's not the language that makes a program slow,
it's the programmer.

Oh, my goodness. Which C++ books have you been reading?
You have some serious misconceptions. I suggest a visit
to www.accu.org and a perusal of the book reviews, followed
by selection and study of one or more of the recommended
books.

-Mike