using System;

using System.Linq;

​

public class Program

{

    static Func<bool> del;

    static Func<int, bool> del2;

    public static void Main()

    {

        //Console.WriteLine("------\tLambdaQueryExpressions");

        //LambdaQueryExpressions();

        //Console.WriteLine("\r\n------\tSimpleLinq");

        //SimpleLinq();

        //Console.WriteLine("\r\n------\tLinqGroupQuery");

        //LinqGroupQuery();

        //Console.WriteLine("\r\n------\tTakeLambdaEx");

        //TakeLambdaEx();

        TestMethod(5);

        // Prove that del2 still has a copy of

        // local variable j from TestMethod.

        bool result = del2(10);

​

        // Output: True

        Console.WriteLine(result);

​

       // Console.ReadKey();

    }

    public static void TestMethod(int input)

    {

        int j = 0;

        // Initialize the delegates with lambda expressions.

        // Note access to 2 outer variables.

        // del will be invoked within this method.

        del = () => { j = 10;  return j > input; };

​

        // del2 will be invoked after TestMethod goes out of scope.

        del2 = (x) => {return x == j; };

​

        // Demonstrate value of j:

        // Output: j = 0 

        // The delegate has not been invoked yet.

        Console.WriteLine("j = {0}", j);        // Invoke the delegate.

        bool boolResult = del();

​

        // Output: j = 10 b = True

        Console.WriteLine("j = {0}. b = {1}", j, boolResult);

    }

    private static void TakeLambdaEx()

    {

        int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };

        var firstNumbersLessThan6 = numbers.TakeWhile(n => n < 6);

        foreach (var number in firstNumbersLessThan6)

            Console.WriteLine(number);

    }

​

    private static void LambdaQueryExpressions()

    {

        string[] names =

        {

        "Jai", "Jayesh", "Joy"

        };

        var filteredNames = Enumerable.Where(names, n => n.Length >= 4).Select(n => n.Length.ToString());

        foreach (var name in filteredNames)

        {

            Console.WriteLine(name.GetType().FullName);

        }

    }

​

    private static void SimpleLinq()

    {

        string[] names =

        {

        "Jack", "Mark", "Harry", "May"

        }

​

        ;

        var query = names.Select(n => new

        {

        Name = n, Length = n.Length

        }

​

        );

        foreach (var row in query)

        {

            Console.WriteLine(row);

        }

    }

​

    private static void LinqGroupQuery()

    {

        string[] names =

        {

        "Jack", "Mark", "Harry", "May"

        }

​

        ;

        var query =

            from n in names

            group n by n[0] into firstCharGrp

                from g in firstCharGrp

                select new

                {

                Key = firstCharGrp.Key, Val = g

                }

​

        ;

        foreach (var row in query)

        {

            Console.WriteLine(row);

        }

    }

}