datatable datakeys

Question

if (chkAll.Checked)

{

   if (!array.Contains(gridview.DataKeys[i].Value))

   {

      array.Add(gridview.DataKeys[i].Value);

   }

}

 

This is to  add the row of a gridview to the ARRAY if the checkbox is checked.

 

What will be the code if I work with DATATABLE instead of GRIDVIEW.