Problem Statement

Select certain elements from an Array into a new Array in a generic way.

To demonstrate, select all even numbers from an Array. As an option, give a second solution which filters destructively, by modifying the original Array rather than creating a new Array.

Let's start with the solution:

+ a, b : ARRAY[INTEGER];
a := ARRAY[INTEGER].create_with_capacity 10 lower 0;
b := ARRAY[INTEGER].create_with_capacity 10 lower 0;
1.to 10 do { i : INTEGER;
  a.add_last i;
};
a.foreach { item : INTEGER;
  (item % 2 = 0).if {
    b.add_last item;
  };
};