C# and LINQ : What is LINQ ?

LINQ (Language Integrated Query) was officially introduced in .NET 3.5. Here is a simple example

string[] currentVideoGames = {"Morrowind", "BioShock"};

// Build a query expression to represent the items in the array

            // that have more than 6 letters.

IEnumerable<string> subset =           from g in currentVideoGames

                                                            where g.Length > 6

                                                            orderby g

                                                            select g;

Some Internals:

            Linq internally converts Linq Queries to some pre-build generics.

IEnumerable<int> subset = from i in numbers where i < 10 select i;

            Is Converted to:

IEnumerable<int> subset = Enumerable.Where<int>(numbers, (i => (i<10)) );

Capturing and saving results of LINQ:

            int[] subsetAsIntArray =

                        (from i in numbers where i < 10 select i).ToArray<int>();

            //It's Enumerable's extension method.

Filtering collection based on type:

            ArrayList myStuff = new ArrayList();

            myStuff.AddRange(new object[] { 10, 400, false, new Car(), "string data" });

            IEnumerable<int> myInts = myStuff.OfType<int>();