How can I declare in C sharp a List with nullable double values?

Question

The purpose is to enumerate the list and count how many nullable values I have, It will be used in order to test some Linq code because I lack of database. The thing is that no matter how I tried to define it I get from my compiler: "The type or namespace name List1' could not be found. Are you missing a using directive or an assembly reference?(CS0246)]".

thanks in advance.

Answer 1

make sure you have:

using System.Collections.Generic;

then it should be as easy as:

List<double?> mylist = new List<double?>();

Answer 2

Are you using mcs? It would be targeting the 1.1 runtime. that would explain "assembly reference not found" Try gmcs for targeting 2.0.

Of course, using System.Collections.Generic; is the cure for "missing using directive"

Answer 3

List<double?> l = new List<double?>();

Works for me... List(Of T) as is Nullable(Of T) is in System.Core do you have that referenced?

Answer 4

With John Boker's answer, you could do something like the following:

List<double?> mylist = new List<double?>();
int nullItemsCount = mylist.Count(item => !item.HasValue);