c# ArrayList Question

[writeallnight]

I can't seem to "disconnect" a "rebuilt" ArrayList of objects from it's source AL; I thought I understood the rules on copying AL Data objects vs. the "clone" Method (and it's simply being a reference to the original ArrayList). The code looks like:

           ArrayList alTemp1 = new ArrayList();
           ArrayList alTemp2 = (ArrayList)Session["AStandingSessionAL"];
 
            for (int i = 0; i < alTemp2.Count; i++) {
                alTemp1.Add((clsAnObject)alTemp2[i]);
                ((clsAnObject)alTemp1[i]).Price = 46.00;
            }
 

This code will change the "Price" to 46.00 for all objects in the ORIGINAL ArrayList (Session["AStandingSessionAL"]). I thought that if you created a new AL and did "Add" from another AL, this would "disconnect" or "Deep Copy" the AL??

Thanks...

[Frinavale]

I can't seem to "disconnect" a "rebuilt" ArrayList of objects from it's source AL; I thought I understood the rules on copying AL Data objects vs. the "clone" Method (and it's simply being a reference to the original ArrayList). The code looks like:

           ArrayList alTemp1 = new ArrayList();
           ArrayList alTemp2 = (ArrayList)Session["AStandingSessionAL"];
 
            for (int i = 0; i < alTemp2.Count; i++) {
                alTemp1.Add((clsAnObject)alTemp2[i]);
                ((clsAnObject)alTemp1[i]).Price = 46.00;
            }
 

This code will change the "Price" to 46.00 for all objects in the ORIGINAL ArrayList (Session["AStandingSessionAL"]). I thought that if you created a new AL and did "Add" from another AL, this would "disconnect" or "Deep Copy" the AL??

Thanks...

When you do:

   alTemp1.Add((clsAnObject)alTemp2[i]);
 

You are are adding the object's memory address (at i) to alTemp1...which is the same memory address as alTemp2. Therefore when you change the Price of the object, both ArrayLists are updated (since they're pointing to the same object).

You should clone the object while adding it to alTemp1.

-Frinny

[Plater]

Yea, frinny is right. It's not so much that the ArrayList is being funnny as it is normal behaviour for objects.

Consider:

Form myform1 = new Form();
Form myform2 = myform1;
//this is roughly what you are doing in your array list copying
 

[writeallnight]

Thanks, but how do I "clone the object" while add ing it?

[Plater]

Have you tried?
alTemp1.Add( ((clsAnObject)alTemp2[i]).Clone() );

[writeallnight]

Doesn't work because my "custom" class/object does not have a method "clone"...

[Plater]

Doesn't work because my "custom" class/object does not have a method "clone"...

Well then you willd need to figure out a method for copy/cloning your custom object.

[Frinavale]

Well then you willd need to figure out a method for copy/cloning your custom object.

I know this is a slight bit off topic but, can you over load operators in C#?
You cannot in VB.NET (found out yesterday and wasn't to impressed).

-Frinny

[writeallnight]

Thanks, I built a "Copy" constructor

[Plater]

I know this is a slight bit off topic but, can you over load operators in C#?
You cannot in VB.NET (found out yesterday and wasn't to impressed).

-Frinny

Yeah I believe you can define what is done on a + or - or various other things like that in C#

[Frinavale]

Yeah I believe you can define what is done on a + or - or various other things like that in C#

It's pretty handy to be able to tell the compiler what to do with your object when + or - (...==..??) operators are used on your object.

Using VB has completely removed the benefits that come from this....

>>Gur<<

I wish I worked in C#