Re: reference

From:

"Bo Persson" <bop@gmb.dk>

Newsgroups:

comp.lang.c++.moderated

Date:

23 May 2006 17:54:33 -0400

Message-ID:

<4dgo92F1agas9U1@individual.net>

"Fei Liu" <fei.liu@gmail.com> skrev i meddelandet
news:1148140960.039034.175430@g10g2000cwb.googlegroups.com...

Hi group, I have a question regarding reference, here is the test
program,

struct C{
  int &x;
};

struct D{
  int d;
};

int main(){
  int x, x1;
  x = 3, x1 = 4;
  int & rx = x;
  rx = x1;

This is equivalent to
x = 4;

// C c, c1; reference member must be member initialized
// c=c1; default assignment operator cannot handle reference
member

  D d, d1;
  D & rd = d;
  rd = d1;

This is equivalent to
d = d1;

}

Here is my question, why is it ok to reassign reference variable but

It isn't!

When assigning to a reference, you actually assign a value to the
object referred to by teh reference.

'int f(C & const c)' declaration is illegal? The common explanation
not
allowing 'int f(C & const c)' is that reference is by nature const
and
cannot be reseated but then why it's ok in my test program to
reassign
reference variable? Thanks for your help.

You can't reseat references, they are just another name for the
original object.

int& rx = x;

just makes rx another name for x. Whatever you do to rx, is actually
performed on x, because they are the same.

Bo Persson

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