Can a reference be 'boxed' and 'unboxed' ala 'pointer to pointer'

[Guest]

HI

can i box and unbox a reference so that i can achieve a 'pointer to pointer' effect. i want to pass a reference as a parameter to a function and then have the function change what the reference is pointing to..

many thank
tham

 

[Philip Rieck]

You don't need any boxing if you have a reference already. You just need to
make the paramater a "ref" param.

....
// the called function:
public void switchReference( ref Hashtable collection)
{
collection = new Hashtable();
}
....
//calling it
....
Hashtable a,b;
a = new Hastable();
b = a;
//now, both a and b referr to the same Hashtable
switchReference(ref a);
//now, b still refers to the original Hashtable, a is a separate one.

HI,

can i box and unbox a reference so that i can achieve a 'pointer to

pointer' effect. i want to pass a reference as a parameter to a function and
then have the function change what the reference is pointing to...

 

[Jon Skeet [C# MVP]]

can i box and unbox a reference so that i can achieve a 'pointer to
pointer' effect. i want to pass a reference as a parameter to a
function and then have the function change what the reference is
pointing to...

No, but you can pass a reference *by* reference with the ref parameter.

See http://www.pobox.com/~skeet/csharp/parameters.html

 

[Guest]

ah pass by ref it is...

many thanks

 

[Guest]

Hi,

HI,

can i box and unbox a reference so that i can achieve a
'pointer to pointer' effect. i want to pass a reference as
a parameter to a function and then have the function change
what the reference is pointing to...

many thanks
tham

There's no direct representation of "pointer to pointer"
in C#, like Philip & Jon said before.

But there is indirect version object[], that can box
any type e.g. :

object[] myBox=new object[1];
myBox[0]=new MyClass();
myBox[0]=2.3;

This table ("myBox") can be parameter for any fuction, and
it should work like "pointer to pointer".

Regards

Marcin