Storing arraylist into another arraylist in c#

Question

I want to insert productDetail arraylist in products arraylist

ArrayList products = new ArrayList();

ArrayList productDetail = new ArrayList();

   foreach (DataRow myRow in myTable.Rows)
     {
     productDetail.Clear();                      
      productDetail.Add( "CostPrice" + "," + myRow["CostPrice"].ToString());

      products.Insert(myTable.Rows.IndexOf(myRow),(object)productDetail);
     }

But each entery in product list is filled with last productdetails ArrayList. What wrong I am doing here?

What does myTable.Rows.IndexOf(myRow) return on each iteration? — khachik
– khachik, Commented Apr 14, 2011 at 11:40
You want to add the ArrayList as a whole or its last item? Can you be more clear about that you are trying to do — Iain Ward
– Iain Ward, Commented Apr 14, 2011 at 11:41
Try products.Add((object)productDetail); instead of Insert. — khachik
– khachik, Commented Apr 14, 2011 at 11:42
ArrayList is deprecated and shouldn't really be used if you can avoid it. Generics is useful here, in particular List<T>. — Darren Young
– Darren Young, Commented Apr 14, 2011 at 11:49

Paolo Tedesco · Accepted Answer · 2011-04-14 11:41:43Z

1

Try moving

ArrayList productDetail = new ArrayList();

inside the foreach loop:

ArrayList products = new ArrayList();
foreach (DataRow myRow in myTable.Rows) {
    ArrayList productDetail = new ArrayList();
    productDetail.Add( "CostPrice" + "," + myRow["CostPrice"].ToString());
    products.Insert(myTable.Rows.IndexOf(myRow),(object)productDetail);
}

The point is that, in your code, you are always adding a reference to the same object: Insert is not making a copy of your list each time...

answered Apr 14, 2011 at 11:41

Paolo Tedesco

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Comments

Cos Callis · Accepted Answer · 2011-04-14 11:41:34Z

1

productDetails only ever has one item in it. Your first step is productDetail.Clear(); Move that outside the foreach to achieve your desired result.

    ArrayList products = new ArrayList();

    ArrayList productDetail = new ArrayList();

    productDetail.Clear(); 

       foreach (DataRow myRow in myTable.Rows)
         {

          productDetail.Add( "CostPrice" + "," + myRow["CostPrice"].ToString());

          products.Insert(myTable.Rows.IndexOf(myRow),(object)productDetail);
         }

answered Apr 14, 2011 at 11:41

Cos Callis

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