using System;

using System.Collections.Generic;

using System.Linq;

​

​

public class Program

{

//          public delegate <T> DlgSummator<T> (T p1, T p2);

    public delegate T DlgSummator<T>(T p1, T p2);

​

    public static void Main(string[] args)

    {   

        Program p = new Program();

​

        DlgSummator<int> intSummator1 = new DlgSummator<int>( p.SumInt );

        DlgSummator<int> intSummator2 = p.SumInt;

        Console.WriteLine("intSummator1=" + intSummator1(2, 5));

        Console.WriteLine("intSummator2=" + intSummator2(12, 51));

        Console.WriteLine("==============");

​

        DlgSummator<string> strSummator1 = new DlgSummator<string>( p.SumStr );

        DlgSummator<string> strSummator2 = p.SumStr;

        Console.WriteLine("strSummator1=" + strSummator1("Hello", "World"));

        Console.WriteLine("strSummator2=" + strSummator2("World", "Hello"));

​

        Console.WriteLine("==============");

//      DlgSummator<T>  tSummator1 = new DlgSummator<T>( p.Sum<T> );

        List<Customer> custList = new List<Customer>();

        custList.Add(new Customer { Id = 1, FirstName = "Joydip", LastName = "Kanjilal", State = "Telengana", City = "Hyderabad", Address = "Begumpet", Country = "India" });

        custList.Add(new Customer { Id = 2, FirstName = "Steve", LastName = "Jones", State = "OA", City = "New York", Address = "Lake Avenue", Country = "US" });

​

        Predicate<Customer> hydCustomers = x => (x.Id == 1) || (x.State == "CA");

        Func<Customer, bool> fnd  = hydCustomers.Invoke;

        Func<Customer, bool> fnc = x => (x.Id == 2 ) || (x.State == "NN"); 

​

        Customer custFound = custList.Find(hydCustomers);

        Console.WriteLine(custFound.FirstName);

        Console.WriteLine(custList.Count(x => (x.Id==1) || (x.State == "OA")));

//      Console.WriteLine(custList.Find(fnc).LastName);

        Customer[] custArr1 = custList.Where( fnd ).ToArray();

        Customer[] custArr2 = custList.Where( x => (x.Id==1) || (x.State == "OA") ).ToArray();

        foreach (var c in custArr2)

        {

            Console.WriteLine( "Id= " + c.Id + "  Fname= " + c.FirstName + "  Lname= " + c.LastName + "  City=" + c.City);              

        }

    }

    int SumInt(int i1, int i2)

    {

        return i1 + i2;

    }

    string SumStr(string i1, string i2)

    {

        return i1 + " " + i2;

    }

    T Sum<T>(T i1, T i2)

    {

        return i1;

    }

}

​

​

class Customer

{

    public int Id { get; set; }

    public string FirstName { get; set; }

    public string LastName { get; set; }

    public string Address { get; set; }

    public string City { get; set; }

    public string State { get; set; }

    public string Country { get; set; }

}

​

​

//  Create a list of customers and store objects of type Customer into it.

​

//  The following is the complete code listing that shows how we can use Predicate delegate to search data.

​

​