Collections C# Book

IntersectsWith keep only elements that are present in that object and in the specified collection.
We keep all the vowels from our set of characters in the following code:

using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
class Sample
{
public static void Main()
{
var letters = new HashSet("the quick brown fox");
letters.IntersectWith("aeiou");
foreach (char c in letters)
Console.Write(c);
}
}
The output:
euio