Question

I have an object allStudents = Dictionary<ClassRoom, List<Student>>()

In Linq how would I get a list of all the students who are male? (student.Gender==”m”) from all the Classrooms?

Ian

Answer 1

Try the following

var maleStudents = allStudents
  .SelectMany(x => x.Values)
  .Where(x => x.Gender=="m");

The trick to this is the SelectMany operation. It has the effect of flattening a collection of List<Student> into a single collection of Student. The resulting list is the same as if you’d lined up each list front to back.