Hello people

I have the following problem, probably it has an easy solution but I
don't know how to solve it:

There's a structure with many fields, with this structure I create a
variable named, for instance 'A'. Then I create a second variable
named 'B'. I would save the complete content of A into B with one or
few commands (not copying field by field) and, later, check if A is
different from B, with C/C++ is very easy, first I make a memcpy of A
into B then, to see if something is different I can use the memcmp

How can do it with C#?

If I write 'B = A' B is just referenced to A so when I change
something into A, B has always the same content of A. And when I
compare A to B with 'if (A == B)' it gives me always true...

Sorry for the banal question, thanks in advance to anyone can help me

Gianco

Gianco <(E-Mail Removed)> wrote:
> I have the following problem, probably it has an easy solution but I
> don't know how to solve it:
>
> There's a structure with many fields, with this structure I create a
> variable named, for instance 'A'. Then I create a second variable
> named 'B'. I would save the complete content of A into B with one or
> few commands (not copying field by field) and, later, check if A is
> different from B, with C/C++ is very easy, first I make a memcpy of A
> into B then, to see if something is different I can use the memcmp
>
> How can do it with C#?
>
> If I write 'B = A' B is just referenced to A so when I change
> something into A, B has always the same content of A. And when I
> compare A to B with 'if (A == B)' it gives me always true...
>
> Sorry for the banal question, thanks in advance to anyone can help me

It sounds like you're actually dealing with classes, not structs.

Could you post a short but complete program which demonstrates the
problem?

See http://www.pobox.com/~skeet/csharp/complete.html for details of
what I mean by that.

--
Jon Skeet - <(E-Mail Removed)>
http://www.pobox.com/~skeet
If replying to the group, please do not mail me too

As you say doing something like 'B = A' means that A and B are pointing to
the same object. Thereafter A == B will always return true. It sounds like
you want to implement a "deep clone". Theres a debate a over whether you
should use the ICloneable interaface, I think the concensus is to avoid it
as it you cannot make a distinction between a shallow or deep copy.

Once you have a deep copy you can implement IComparable such that the
following will test for equality:

YourType A;
YourType B;

if(A.CompareTo(B) == 0)
{
//Same value;
}

"Jon Skeet [C# MVP]" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> Gianco <(E-Mail Removed)> wrote:
> > I have the following problem, probably it has an easy solution but I
> > don't know how to solve it:
> >
> > There's a structure with many fields, with this structure I create a
> > variable named, for instance 'A'. Then I create a second variable
> > named 'B'. I would save the complete content of A into B with one or
> > few commands (not copying field by field) and, later, check if A is
> > different from B, with C/C++ is very easy, first I make a memcpy of A
> > into B then, to see if something is different I can use the memcmp
> >
> > How can do it with C#?
> >
> > If I write 'B = A' B is just referenced to A so when I change
> > something into A, B has always the same content of A. And when I
> > compare A to B with 'if (A == B)' it gives me always true...
> >
> > Sorry for the banal question, thanks in advance to anyone can help me
>
> It sounds like you're actually dealing with classes, not structs.
>
> Could you post a short but complete program which demonstrates the
> problem?
>
> See http://www.pobox.com/~skeet/csharp/complete.html for details of
> what I mean by that.
>
> --
> Jon Skeet - <(E-Mail Removed)>
> http://www.pobox.com/~skeet
> If replying to the group, please do not mail me too

Yes I supposed to work with a structure but it was declared as class,
now I changed something to use it as a structure and now make test if
the problem is solved. Thank you very much

Gianco