Question

Using linq, How can I sort an array and after that return all numbers that are smaller then X

For sorting I use that:(is it a good way?)

var sorted = (from number in array orderby number ascending select number).ToArray();

So i have it sorted in ‘sorted’ array.

how can i return all numbers in it that are smaller then X.

Answer 1

Why do you want to sort before you filter? That is less efficient than to filter first and order the rest:

var sorted = array.Where(i => i < x).OrderBy(i => i).ToArray(); 

or in query syntax:

var sorted = (from i in array
              where i < x
              orderby i
              select i).ToArray(); 

Order of LINQ extension methods does not affect performance? (the title is misleading, actually OrderBy is one of the exceptions where the order matters as E.Lippert explains in his answer)