changing reference

[winstoon@gmail.com]

Hi,

consider the following code...

string a = "1";
string b = "2";
string& c = a;

how do I change c to refer to b instead of a?

[Victor Bazarov]

Re: changing reference

winstoon@gmail. com wrote:

consider the following code...
>
string a = "1";
string b = "2";
string& c = a;
>
how do I change c to refer to b instead of a?

There is no legal C++ way.

V
--
Please remove capital 'A's when replying by e-mail
I do not respond to top-posted replies, please don't ask

[Kai-Uwe Bux]

Re: changing reference

winstoon@gmail. com wrote:

consider the following code...
>
string a = "1";
string b = "2";
string& c = a;
>
how do I change c to refer to b instead of a?

There is no "how": you cannot reseat a reference.


Best

Kai-Uwe Bux

[Peter]

Re: changing reference

On Jul 17, 8:14 am, winst...@gmail. com wrote:

Hi,
>
consider the following code...
>
string a = "1";
string b = "2";
string& c = a;
>
how do I change c to refer to b instead of a?

When a reference is initialized, it remains bound to that object as
long as the reference exists. There is no way to rebind a reference to
a different object.

[BobR]

Re: changing reference


<winstoon@gmail .comwrote in message...

Hi,
consider the following code...
string a = "1";
string b = "2";
string& c = a;
how do I change c to refer to b instead of a?
>

Can't reseat 'c'.

{
std::string a = "1";
std::string b = "2";
std::string &c( a );
std::cout<<"str ing &c(a) c="<<c<<std::en dl;
a.swap( b );
std::cout<<"a.s wap(b) c="<<c<<std::en dl;
}
// out: string &c(a) c=1
// out: a.swap(b) c=2

--
Bob R
POVrookie

[BobR]

Re: changing reference


BobR <removeBadBobR@ worldnet.att.ne twrote in message...

{
std::string a = "1";
std::string b = "2";
std::string &c( a );
std::cout<<"str ing &c(a) c="<<c<<std::en dl;
a.swap( b );
std::cout<<"a.s wap(b) c="<<c<<std::en dl;
}
// out: string &c(a) c=1
// out: a.swap(b) c=2

or, scope it:

{
std::string a = "1";
std::string b = "2";
{
std::string &c( a );
std::cout<<"str ing &c(a) c="<<c<<std::en dl;
}
{
std::string &c( b );
std::cout<<"str ing &c(b) c="<<c<<std::en dl;
}
}
// out: string &c(a) c=1
// out: string &c(b) c=2

--
Bob R
POVrookie

[Sarath]

Re: changing reference

On Jul 17, 9:14 am, winst...@gmail. com wrote:

Hi,
>
consider the following code...
>
string a = "1";
string b = "2";
string& c = a;
>
how do I change c to refer to b instead of a?

It's not possible to change the reference. Reference is not a pointer
to the object. It's simply the same object. Something we can call
alias. So assignment after initializing reference is something like
you assign a value to the object it is referring.

See

http://www.parashift.com/c++-faq-lite/references.html#faq-8.2

Regards,
Sarath

http://sarathc.wordpress.com/

[sun1991]

Re: changing reference

You can not, use pointer instead.

[Guest]

Re: changing reference

On Jul 17, 8:14 am, winst...@gmail. com wrote:

Hi,
>
consider the following code...
>
string a = "1";
string b = "2";
string& c = a;
>
how do I change c to refer to b instead of a?

So called "reference" is the alias of the object it refers to. The
referer and referee have the same physical address, and the referer's
address is set at the time of initialization, it can not be changed
anyway. Consider the example below:

nt main()
{
int a = 1 ;
int b = 2;
int& c = a;

cout << "c is " << c << endl;

c = b;
cout << "Now a is:" << a << endl;

c = 3;
cout << "Now b still is:" << b << endl;

cout << "But now a is:" << a << endl;

cout << "c's address:" << &c << endl;
cout << "a's address:" << &a << endl;

return 0;
}

[James Kanze]

Re: changing reference

On Jul 17, 4:14 am, "BobR" <removeBadB...@ worldnet.att.ne twrote:

<winst...@gmail .comwrote in message...

consider the following code...
string a = "1";
string b = "2";
string& c = a;
how do I change c to refer to b instead of a?

Can't reseat 'c'.

{
std::string a = "1";
std::string b = "2";
std::string &c( a );
std::cout<<"str ing &c(a) c="<<c<<std::en dl;
a.swap( b );
std::cout<<"a.s wap(b) c="<<c<<std::en dl;}

// out: string &c(a) c=1
// out: a.swap(b) c=2

I'm not sure what this is supposed to show. Consider:

std::cout.setf( std::ios::boola lpha ) ;
std::string a = "1" ;
std::string b = "2" ;
std::cout << "&a = " << &a << ", &b = " << &b << std::endl ;
std::string& c = a ;
std::cout << "a = " << a
<< ", b = " << b
<< ", c = " << c
<< ", &c = " << &c << std::endl ;
a.swap( b ) ;
std::cout << "a = " << a
<< ", b = " << b
<< ", c = " << c
<< ", &c = " << &c << std::endl ;

I get:
&a = ffbedfe0, &b = ffbedfd8
a = 1, b = 2, c = 1, &c = ffbedfe0
a = 2, b = 1, c = 2, &c = ffbedfe0
You've swapped a and b, but you've not changed the binding of c
in any way. Once constructed, there is no legal way to change
the binding of a reference.

--
James Kanze (GABI Software) email:james.kan ze@gmail.com
Conseils en informatique orientée objet/
Beratung in objektorientier ter Datenverarbeitu ng
9 place Sémard, 78210 St.-Cyr-l'École, France, +33 (0)1 30 23 00 34

[terminator]

Re: changing reference

On Jul 17, 4:14 am, winst...@gmail. com wrote:

Hi,
>
consider the following code...
>
string a = "1";
string b = "2";
string& c = a;
>
how do I change c to refer to b instead of a?

Sorry, you can`t do that ,but I suggest using pointers instead:

string a = "a";
string b = "b";
string d = "d";
string e = "e";

string * sptr = & a;
( * sptr ) = "a is changed";

sptr = & b;
( * sptr ) = "b is changed";

( * ( sptr = & d ) ) = "d is changed";

( *( & e ) ) = "e is changed";

regards,
FM.