Question

I have an object model that contains a list of objects and these objects have a property that’s defined as a short. It looks somewhat like this:

public class MyObject
{
   public short TheNumber { get; set;}
}

List<MyObject> TheListOfMyObjects = SomeMethodThatReturnsList();

Now I want to do a sum on TheNumber of all the objects in the list so I’m writing this:

var TheSum = (from a in TheListOfMyObjects 
              where....
              select a.TheNumber).Sum();

I get an error saying that there’s no definion for Sum(). Why is this not working and how do I fix it?

Edit:

I have this that works:

var TheCount = (from a in TheListOfMyObjects 
                where....
                select a).Count();

So yes, I have System.Linq in the using statement. Not sure why the downvotes.

Answer 1

Sum doesn’t have an overload for short (Int16), i.e. http://msdn.microsoft.com/en-us/library/system.linq.enumerable.sum.aspx

Either cast/parse first or do .Sum(i => i)