Question

How is the OrderByDescending used ?

I have a label, Circles, declared like this

ReadOnlyCollection<FlangeCircle> Circles

which contain a variabel, Diameter of the type double

I want to sort them based on the diamter so I try

FlangeCircle<FlangeCircle> query = Circles.OrderByDescending(p => p.Diameter);

but that will not go throug the compiler, but the following does

var query = Circles.OrderByDescending(p => p.Diameter);

Why is that and how do I declare query with a “correct” type instead ?

/Stefan

Answer 1

The type of the variable is the problem:

FlangeCircle<FlangeCircle> query = ...

FlangeCircle<FlangeCircle> doesn’t make sense as a type, and certainly isn’t what’s returned by OrderByDescending. You almost certainly want:

IEnumerable<FlangeCircle> query = Circles.OrderByDescending(p => p.Diameter);

Or if you want to be able to perform ThenBy/ThenByDescending operatorions on query:

IOrderedEnumerable<FlangeCircle> query = ...;