c# - Linq: List of lists to a long list

Question

I've got an object of type A which consists of a list of objects of type B:

class A { list<B> Alist;}
class B { string C; string D;}

In my program I have a list of A objects:

list<A> listOfA = computeAList();

and I would like to select all the C strings in that list. The following statement I hoped would give me the result I wanted; it returns a list of lists containing the C's:

var query = from objectA in listOfA
            select objectA.Alist.FindAll(x => x.C.Length > 0).C;

Is there a way to get a single list of all the C's instead?

Answer 1

ybo's answer would have been my first response too. The query expression equivalent of this is:

var query = from a in computeAList()
            from b in a.Alist
            select b.C;

For the sake of completeness, the other answers in this thread are variations on the same theme.

From ybo (the exact same query, expressed as dot notation):

var query = listOfA.SelectMany(a => a.Alist, (a, b) => b.C);

From Ray Hayes (including the Where clause; I've reformatted slightly):

var query = listOfA.SelectMany(a => a.AList, (a, b) => b.C)
                   .Where(c => c.Length > 0);