C++: can someone explain to me, a C/Hw guy, what the diff is between a reference (&) and a pointer?

[bo]

And why and where one should use one vs. the other?

Verbally, it seems like semantics to me--but obviously there is some
actual difference that makes references different and or preferable
over pointers in some cases...

TIA

[Peter Koch Larsen]

"bo" <[e-mail] m> skrev i en meddelelse
news:9q******** *************** *********@4ax.c om...

And why and where one should use one vs. the other?

Verbally, it seems like semantics to me--but obviously there is some
actual difference that makes references different and or preferable
over pointers in some cases...

TIA

Have you read the faq pointed to by others? I believe it is quite good. No
specific implementation is required in the standard. That said, you can be
quite sure that a reference in the general case will be represented by a
pointervalue. In special cases, the value of the reference will be known and
no pointer will be stored.

/Peter

[David Lindauer]

the main usefulness in my mind is maintainability ; once you create a
reference variable you *know* it is always going to point to the same
thing, and that it is going to be non-null. But if you are reading code
with pointers in it you may not be sure that the author isn't going to
go changing the meaning later down in the code, and if he does you may
not be able to tell immediately whether it was intended or a bug.
Internally however, compilers I have seen have typically implemented
reference variables the same way they did pointers in terms of low-level
behavior.

Personally I spend a *lot* more time maintaining and reusing than I do
cutting new code, so any help I can get in terms of cues as to the
intended purpose and/or limitations of things are really helpful.

David

bo wrote:

And why and where one should use one vs. the other?

Verbally, it seems like semantics to me--but obviously there is some
actual difference that makes references different and or preferable
over pointers in some cases...

TIA

[bo]

Thanks to all who replied and the pointer (reference?) to the FAQ on
the subject! I am enlightened.... .

Regards,

Bo

[Rich Grise]

On Thursday 16 September 2004 06:12 am, JKop did deign to grace us with the
following:

bo posted:

And why and where one should use one vs. the other?

.... References are nicer to work with, in that they behave
exactly like real variables. a) They can be reseated. One minute they can point East,
the next South West.
This is probably just style, but this is why Pointers Are
Bad(TM). ;-)
b) They can be incremented/decremented. If you have a
pointer to a character, you simply increment it and it
points to the next character in the string.
I wouldn't even do this. If I really had to reference
string chars, I'd probably use *(ptr + i) and so on (i.e.,
not change the pointer itself if I didn't have to.) but
I guess we've already covered that, haven't we? (i.e. then
use a reference.) :-)
So...

Use references. If you can't, eg. you need to increment it
or seseat it, then *resort* to pointers.

Yeah - I cut my teeth on C with K&R at my elbow, and a tutor
who was about as smart as me - I wrote in a lot of printfs. ;-)
and have done a little thinking about pointers vs. references,
and I can't think of a single thing I'd want to do in real C++
that would need a pointer at all. I'm not porting any legacy
code - I intend to lift all new snippets to paste. ;-)
(I can pass for a programmer, but mostly what I do is copy
and paste other people's code. :-)

Cheers!
Rich

[Richard Herring]

In message <btT2d.1520$Co1 .271@trnddc02>, Rich Grise <nu**@example.n et>
writes

On Thursday 16 September 2004 06:12 am, JKop did deign to grace us with the
following:
[...]

b) They can be incremented/decremented. If you have a
pointer to a character, you simply increment it and it
points to the next character in the string.

I wouldn't even do this. If I really had to reference
string chars, I'd probably use *(ptr + i) and so on (i.e.,
not change the pointer itself if I didn't have to.)

Pointers Are Iterators, so there's no harm in using the natural iterator
operations with them.
but
I guess we've already covered that, haven't we? (i.e. then
use a reference.) :-)

So...

Use references. If you can't, eg. you need to increment it
or seseat it, then *resort* to pointers.
Yeah - I cut my teeth on C with K&R at my elbow, and a tutor
who was about as smart as me - I wrote in a lot of printfs. ;-)
and have done a little thinking about pointers vs. references,
and I can't think of a single thing I'd want to do in real C++
that would need a pointer at all.

See above.
I'm not porting any legacy
code - I intend to lift all new snippets to paste. ;-)
(I can pass for a programmer, but mostly what I do is copy
and paste other people's code. :-)

--
Richard Herring