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Some of the new stuff in .Net 3.x simply/examplyfied.

  • 项目

Just thought I put together a small class that shows some of the new features in .Net 3.x

I have no intention of trying to explain how it works in detail (there is good documentation out there), you should see this more as a reference.

Also, this is not a full list of all that is new, no LINQ for example; it is more to show the ones that may save you typing J

In this class:

Auto-Implemented Properties

Anonymous Types

Object and Collection Initializer

Extension Methods

Lambda Expressions

using System;

using System.Collections;

using System.Collections.Generic;

using System.Linq;

using System.Text;

namespace SomeDemoStuff

{

    class Program

    {

        /*********************************************************

        Auto-Implemented Properties

        https://msdn.microsoft.com/en-us/library/bb384054.aspx

        *********************************************************/

   // Oldschool

        private int oldAge;

        public int OldAge

        {

            get { return oldAge; }

            set { oldAge = value; }

        }

        // Newschool

        public int NewAge{get; set;}

        // Note, you can't mix old/new, ie:

        //public int NewAge { get; set{value + 4}; }

        static void Main(string[] args)

        {

            /*********************************************************

            Anonymous Types

            https://msdn.microsoft.com/en-us/library/bb397696.aspx

            *********************************************************/

            for (int i = 20; i < 25; i++)

            {

                var anonymousPerson = new { Age = i, AgeInTenYears = i + 10 };

                Console.WriteLine("Age now {0}, age in ten years {1}", anonymousPerson.Age, anonymousPerson.AgeInTenYears);

            }

            // Can only access it within the scope, so the following fails since it is outside scope:

            //int i = person.Age;

            /*********************************************************

            Object and Collection Initializers

            https://msdn.microsoft.com/en-us/library/bb384062.aspx

            *********************************************************/

            // *** Object Initializer ***

            // This uses the Person class below. Which uses auto implemented properties

            // Old way

            Person oldPerson = new Person();

  oldPerson.Age = 29;

            oldPerson.Name = "Michael";

            // New way

            Person newPerson = new Person { Age = 30, Name = "Michael" };

            // *** Collection Initializer ***

            List<string> names = new List<string> { "Michael", "John", "Steve", "Charles" };

            /*********************************************************

            Extension Methods

            https://msdn.microsoft.com/en-us/library/bb383977.aspx

            *********************************************************/

            // The short story, this gives you the ability to add methods to existing types.

            int age = 29;

            // Old way

            int newAge = AddFive(age);

    Console.WriteLine("Current age {0}, age in 5 years {1}", age, newAge);

            // New way - adding method to type.

            Console.WriteLine("Current age {0}, age in 10 years {1}", age, age.AddTen());

            /*********************************************************

            Lambda Expressions

            https://msdn.microsoft.com/en-us/library/bb397687.aspx

            *********************************************************/

            // The lambda expression reads as "goes to".

            // The leftsid is the input parameter, the right one is the expression.

            // In the case below, persons over 30 goes into the var variable called personsOver30

            // (This example uses Object/List intitializers and auto matic properties as well as Extension methods (persons.Where))

            List<Person> persons = new List<Person>

            {

                new Person{Age = 10, Name="Pete"},

                new Person{Age = 20, Name="John"},

                new Person{Age = 30, Name="Steve"},

                new Person{Age = 40, Name="Michael"}

            };

            var personsOver30 = persons.Where(p => p.Age >= 30);

            foreach (Person p in personsOver30)

                Console.WriteLine(p.ToString());

        }

        // Old method

        public static int AddFive(int age)

        {

            return age + 5;

        }

    }

    class Person

    {

        public int Age { get; set; }

        public string Name { get; set; }

        public override string ToString()

        {

            return string.Format("Name: {0}, Age: {1}", Name, Age);

        }

    }

    static class ExtensionMethods

    {

        public static int AddTen(this int inValue)

        {

            return inValue + 10;

        }

    }

}

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