I need the sum of two fields that are in different DataTables

Question

The problem is that in c# I can't subtract the objects, so I need to figure out how to get the integers out of them and then do the arithmetic? Here's the code.. what am I missing?

dsfDataSet.itemTotals.Compute( "SUM(priceSum)", String.Empty ) - dsfDataSet.discountItems.Compute("SUM(totDiscount)", String.Empty)

Answer 1

If you know the data is integer, you should use Convert.ToInt16 or similar functions to extract the integers. Be sure to add additional exception handling, in case the data turns out to be non integer.

Answer 2

What is the return type of your Compute function? Object? Or a defined type?

If defined, you CAN overload the '-' operator, you know? Otherwise, what is stopping you from creating a method that take those two structures and return the integer result you need? Why must it be with '-' ?

Answer 3

you can use int.TryParse as the output of DataTable.Compute is object

int priceSum,totDiscount;

if(int.TryParse(dsfDataSet.itemTotals.Compute( "SUM(priceSum)", String.Empty ).ToString(),out priceSum))
{
  if(int.TryParse(dsfDataSet.discountItems.Compute("SUM(totDiscount)", String.Empty).ToString(),out totDiscount))
  {
    priceSum - totDiscount;
  }
}