Install-Package mongocsharpdriver

  public class Author
    {
        public ObjectId Id { get; set; }
        public string Name { get; set; }
    }

public class Language
    {
        public ObjectId Id { get; set; }
        public string Name { get; set; }
    }

  public class Book
    {
        public ObjectId Id { get; set; }
        public string Title { get; set; }
        public string ISBN { get; set; }
        public int Price { get; set; }
        public List<Author> Authors { get; set; }
        public Language Language { get; set; }
    }

           var book =new Book()
           {
               Title = "Gone With Wind",
               ISBN = "43442424",
               Price = 50000,
               Language = new Language()
               {
                  Name = "Persian"
               },
               Authors = new List<Author>()
               {
                   new Author()
                   {
                       Name = "Margaret Mitchell"
                   },
                     new Author()
                   {
                       Name = "Ali Mahboobi (Translator)"
                   },
               }
           };

var client = new MongoClient();

 string connectionString = "mongodb://localhost:27017";
            MongoClientSettings settings = MongoClientSettings.FromUrl(new MongoUrl(connectionString));
            var client = new MongoClient(settings);

var db = client.GetDatabase("publisher");

var collection = db.GetCollection<Book>("books");

collection.InsertOneAsync(book);

فعلا موجودیت‌های مؤلفان و زبان به دلیل اینکه سند اختصاصی برای خود ندارند، با صفر پر شده‌اند؛ ولی شناسه یکتای سند، مقدار خود را گرفته است.

عملیات خواندن

       var client = new MongoClient();
            var db = client.GetDatabase("publisher");
            db.DropCollection("books");
            var collection = db.GetCollection<Book>("books");
            var book =new Book()
           {
               Title = "Gone With Wind",
               ISBN = "43442424",
               Price = 50000,
               Year = 1936,
               LastStock = DateTime.Now.AddDays(-13),
               Language = new Language()
               {
                  Name = "Persian"
               },
               Authors = new List<Author>()
               {
                   new Author()
                   {
                       Name = "Margaret Mitchell"
                   },
                     new Author()
                   {
                       Name = "Ali Mahboobi (Translator)"
                   },
               }
           };

            var book2 = new Book()
            {
                Title = "Jane Eyre",
                ISBN = "87897897",
                Price = 60000,
                Year = 1847,
                LastStock = DateTime.Now.AddDays(-5),
                Language = new Language()
                {
                    Name = "English"
                },
                Authors = new List<Author>()
               {
                   new Author()
                   {
                       Name = "Charlotte Brontë"
                   },
                   
               }
            };


            var book3 = new Book()
            {
                Title = "White Fang",
                ISBN = "43442424",
                Price = 50000,
                Year = 1936,
                LastStock = DateTime.Now.AddDays(-13),
                Language = new Language()
                {
                    Name = "English"
                },
                Authors = new List<Author>()
               {
                   new Author()
                   {
                       Name = "Jack London"
                   },
                     new Author()
                   {
                       Name = "Philippe Mignon"
                   },
               }
            };

            var book4 = new Book()
            {
                Title = "The Lost Symbol",
                ISBN = "43442424",
                Price = 3500000,
                Year = 2009,
                LastStock = DateTime.Now.AddDays(-17),
                Language = new Language()
                {
                    Name = "Persian"
                },
                Authors = new List<Author>()
               {
                   new Author()
                   {
                       Name = "Dan Brown"
                   },
                     new Author()
                   {
                       Name = "Mehrdad"
                   },
               }
            };

            var book7 = new Book()
            {
                Title = "The Lost Symbol",
                ISBN = "43442424",
                Price = 47000000,
                Year = 2009,
                LastStock = DateTime.Now.AddDays(-56),
                Language = new Language()
                {
                    Name = "Persian"
                },
                Authors = new List<Author>()
               {
                   new Author()
                   {
                       Name = "Dan Brown"
                   },
                     new Author()
                   {
                       Name = "Mehrdad"
                   },
               }
            };
            var book5= new Book()
            {
                Title = "The Help",
                ISBN = "45345e3er3",
                Price = 9000000,
                Year = 2009,
                LastStock = DateTime.Now.AddDays(-2),
                Language = new Language()
                {
                    Name = "Enlish"
                },
                Authors = new List<Author>()
               {
                   new Author()
                   {
                       Name = "Kathryn Stockett"
                   },
               }
            };

            var book6 = new Book()
            {
                Title = "City of Glass",
                ISBN = "454534545",
                Price = 500000,
                Year = 2009,
                LastStock = DateTime.Now,
                Language = new Language()
                {
                    Name = "Persian"
                },
                Authors = new List<Author>()
               {
                   new Author()
                   {
                       Name = "Cassandra Clare"
                   },
                   new Author()
                   {
                       Name = "Ali"
                   },

               }
            };
            var books = new List<Book> {book, book2, book3, book4, book5, book6,book7};

            collection.InsertManyAsync(books);

            var client = new MongoClient();
            var db = client.GetDatabase("publisher");
            var collection = db.GetCollection<Book>("books");
            var filter=new BsonDocument();
            var docs = collection.Find(filter).ToList();
            foreach (var book in docs)
            {
                Console.WriteLine(book.Title + " By "+ book.Authors[0].Name);
            }

Gone With Wind By Margaret Mitchell
Jane Eyre By Charlotte Brontë
White Fang By Jack London
The Lost Symbol By Dan Brown
The Help By Kathryn Stockett
City of Glass By Cassandra Clare
The Lost Symbol By Dan Brown

var filter = Builders<Book>.Filter.Eq("Year", 2009);

            var docs = collection.Find(filter).ToList();
            foreach (var book in docs)
            {
                Console.WriteLine(book.Title + " By "+ book.Authors[0].Name);
            }

The Lost Symbol By Dan Brown
The Help By Kathryn Stockett
City of Glass By Cassandra Clare
The Lost Symbol By Dan Brown

   // var filter=new BsonDocument();
            var filterBuilder = Builders<Book>.Filter;
            var filter= filterBuilder.Eq("Year", 2009) | filterBuilder.Gte("Price",700000);

            var docs = collection.Find(filter).ToList();
            foreach (var book in docs)
            {
                Console.WriteLine(book.Title + " By "+ book.Authors[0].Name);
            }

Gone With Wind By Margaret Mitchell
White Fang By Jack London
The Lost Symbol By Dan Brown
The Help By Kathryn Stockett
City of Glass By Cassandra Clare
The Lost Symbol By Dan Brown

var docs = collection.AsQueryable().Where(x => x.Year == 2009 || x.Price <= 50000).ToList();

  var sort = Builders<Book>.Sort.Ascending("Title").Descending("Price");
            var docs = collection.Find(filter).Sort(sort).ToList();
            foreach (var book in docs)
            {
                Console.WriteLine(book.Title + " By "+ book.Authors[0].Name);
            }

City of Glass By Cassandra Clare
Gone With Wind By Margaret Mitchell
The Help By Kathryn Stockett
The Lost Symbol By Dan Brown
The Lost Symbol By Dan Brown
White Fang By Jack London

     [HttpPost,AjaxOnly, ValidateAntiForgeryToken]
        public virtual JsonResult Create(AddDeviceGroupViewModel deviceGroupViewModel)
        {
            if (ModelState.IsNotValid())
            {
                Response.StatusCode = (int)HttpStatusCode.BadRequest;
                return Json(new { success = false, message = ModelState.FirstErrorMessage(), notificationType = NotificationType.Error }, JsonRequestBehavior.AllowGet);
            }
            var result = _deviceGroupService.Add(deviceGroupViewModel);

           // other codes

        }

function SaveFailure(data) {
    $("button[type=submit]").prop('disabled', false);
    var result = $.parseJSON(data.responseText);
    showMessage(result.message, result.notificationType);
}

Response.StatusCode = (int)HttpStatusCode.BadRequest;

    var result = $.parseJSON(data.responseText);

  Response.TrySkipIisCustomErrors = true;

install-package MongoDB.Driver.GridFS

var client = new MongoClient();
var db = client.GetDatabase("publisher");
IGridFSBucket bucket = new GridFSBucket(db);

byte[] source=File.ReadAllBytes(@"D:\Untitled.png");
var options = new GridFSUploadOptions
            {
                ChunkSizeBytes = 64512, // 63KB
                Metadata = new BsonDocument
                {
                    { "CoverType", "Front" }, 
                    { "copyrighted", true }
                }
            };

 var options = new GridFSUploadOptions
            {
                ChunkSizeBytes = 64512, // 63KB
                Metadata = metaData.ToBsonDocument()
            };

 var id = bucket.UploadFromBytes("GoneWithTheWind", source, options);

[BsonId]
public ObjectId Id { get; set; }

var bytes = bucket.DownloadAsBytes(id);

var client = new MongoClient();
var db = client.GetDatabase("publisher");
IGridFSBucket bucket = new GridFSBucket(db);
var image=bucket.DownloadAsBytesByName("City of Glass-cover");
File.WriteAllBytes(@"D:\a.jpg",image);

var client = new MongoClient();
var db = client.GetDatabase("publisher");
IGridFSBucket bucket = new GridFSBucket(db);
var options = new GridFSDownloadByNameOptions
            {
                Revision = 0
            };
var image=bucket.DownloadAsBytesByName("City of Glass-cover",options);
File.WriteAllBytes(@"D:\a.jpg",image);

var client = new MongoClient();
var db = client.GetDatabase("publisher");
IGridFSBucket bucket = new GridFSBucket(db);
var filter = Builders<GridFSFileInfo>.Filter.Gte(x => x.Length , 600);
var sort = Builders<GridFSFileInfo>.Sort.Descending(x => x.UploadDateTime);
var options =new GridFSFindOptions()
            {
                Limit = 3,
                Sort = sort
            };
var cursor = bucket.Find(filter, options);
var list = cursor.ToList();

var filter = Builders<GridFSFileInfo>.Filter.Eq("metadata.CoverType","Front");

bucket.Rename(id, newFilename);

//یا در حالت غیرهمزمان
await bucket.RenameAsync(id, newFilename);

bucket.Delete(id);

//یا
await bucket.DeleteAsync(id);

bucket.Drop();

//یا
await bucket.DropAsync();

 Install-Package MvcAjaxPager

public class Topic
{
   public int Id;
   public string Title;
   public string Text;
}

public class TopicService
{
    public static IEnumerable<Topic> Topics = new List<Topic>() {
       new Topic{Id=1,Title="Title 1",Text= "Text 1"},
       new Topic{Id=2,Title="Title 2",Text="Text 2"},
       new Topic{Id=3,Title="Title 3",Text="Text 3"},
       new Topic{Id=4,Title="Title 4",Text="Text 4"},
       new Topic{Id=5,Title="Title 5",Text="Text 5"},
       new Topic{Id=6,Title="Title 6",Text="Text 6"},
       new Topic{Id=7,Title="Title 7",Text="Text 7"},
       new Topic{Id=8,Title="Title 8",Text="Text 8"},
       new Topic{Id=9,Title="Title 9",Text="Text 9"},
       new Topic{Id=10,Title="Title 10",Text="Text 10"},
       new Topic{Id=11,Title="Title 11",Text="Text 11"},
       new Topic{Id=12,Title="Title 12",Text="Text 12"},
       new Topic{Id=13,Title="Title 13",Text="Text 13"},
       new Topic{Id=14,Title="Title 14",Text="Text 14"},
       new Topic{Id=15,Title="Title 15",Text="Text 15"},
       new Topic{Id=16,Title="Title 16",Text="Text 16"},
       new Topic{Id=17,Title="Title 17",Text="Text 17"},
       new Topic{Id=18,Title="Title 18",Text="Text 18"},
       new Topic{Id=19,Title="Title 19",Text="Text 19"},
       new Topic{Id=20,Title="Title 20",Text="Text 20"},
       new Topic{Id=21,Title="Title 21",Text="Text 21"},
       new Topic{Id=22,Title="Title 22",Text="Text 22"},
      };

    public static IEnumerable<Topic> GetAll()
    {
       return Topics.OrderBy(row => row.Id);
    }
}

public class ListViewModel
{
   public IEnumerable<Topic> Topics { get; set; }
   public int PageIndex { get; set; }
   public int TotalItemCount { get; set; }
}

public ActionResult Index(int page = 1)
{
       var topics = TopicService.GetAll ();
       int totalItemCount = topics.Count();
       var model = new ListViewModel()
       {
              PageIndex = page,
              Topics = topics.OrderBy(p => p.Id).Skip((page - 1) * 10).Take(10).ToList(),
              TotalItemCount = totalItemCount
       };

       if (!Request.IsAjaxRequest())
       {
              return View(model);
       }

       return PartialView("_TopicList", model);
}

@using MvcAjaxPager
@model ListViewModel

@Html.AjaxPager(Model.TotalItemCount, 10, Model.PageIndex, "Index", "Home", null, new PagerOptions
   {
       ShowDisabledPagerItems = true,
       AlwaysShowFirstLastPageNumber = true,
       HorizontalAlign = "center",
       ShowFirstLast = false,
       CssClass = "NavigationBox",
       AjaxUpdateTargetId = "dvTopics",
       AjaxOnBegin = "AjaxStart",
       AjaxOnComplete = "AjaxStop"
   }, null, null)

<table><tr><th>
            @Html.DisplayName("ID")</th><th>
            @Html.DisplayName("Title")</th><th>
            @Html.DisplayName("Text")</th></tr>

    @foreach (var topic in Model.Topics)
    {
        <tr><td>
                @topic.Id</td><td>
            @topic.Title</td><td>
            @topic.Text</td></tr>
    }</table>

@Html.AjaxPager(Model.TotalItemCount, 10, Model.PageIndex, "Index", "Home", null, new PagerOptions
   {
       ShowDisabledPagerItems = true,
       AlwaysShowFirstLastPageNumber = true,
       HorizontalAlign = "center",
       ShowFirstLast = true,
       FirstPageText = "اولین",
       LastPageText = "آخرین",
       MorePageText = "...",
       PrevPageText = "قبلی",
       NextPageText = "بعدی",
       CssClass = "NavigationBox",
       AjaxUpdateTargetId = "dvTopics",
       AjaxOnBegin = "AjaxStart",
       AjaxOnComplete = "AjaxStop"
   }, null, null)

@using MvcAjaxPager
@model ListViewModel
@{
    Layout = null;
}<!DOCTYPE html><html><head><meta name="viewport" content="width=device-width" /><title>Index</title></head><body><div id="dvTopics">
        @{
            @Html.Partial("_TopicList", Model);
        }</div><script type="text/javascript" src="@Url.Content("~/Scripts/jquery-1.7.2.min.js")"></script><script type="text/javascript" src="@Url.Content("~/Scripts/path.min.js")"></script><script type="text/javascript" src="@Url.Content("~/Scripts/jquery.pager-1.0.1.min.js")"></script><script type="text/javascript">
        $('.NavigationBox').pager();

        //pagination before start
        function AjaxStart() {
            console.log('Start AJAX call. Loading message can be shown');
        }
        // pagination - after request
        function AjaxStop() {
            console.log('Stop AJAX call. Loading message can be hidden');
        };
    </script></body></html>

تصویر بالا به شما نشان میدهد که کلاینت‌ها ابتدا به مسیریاب‌ها متصل می‌شوند. این مسیریاب‌ها بر اساس فایل‌های پیکربندی که مدیر سیستم آماده کرده است و شامل تنظیمات موازنه گر میباشد، کلاینت‌ها را به شاردینگ‌های‌ها مورد نظر متصل میکنند و بعد از آن هم انتخاب سرور از رپلیکیشن.

عملیات Chunk یا قطعه سازی فایل‌ها، بر اساس همین تعداد شاردینگ‌های مختلف می‌باشد که به صورت انتزاعی یا مفهومی ایجاد شده‌است و شامل دیتای اصلی نمیشود؛ بلکه شامل اطلاعاتی برای هر قطعه از دیتاها میشود که شامل یک کلید به نام SharedKey میباشد و دو مقدار Min و Max را برای هر رنج دیتا شامل میشود.

بعد از اینکه Chunk‌های یک فایل مشخص شد، مونگو برای حفظ موازنه و بالانس شاردینگ‌ها، شروع به تقسیم این چانک‌ها میکند. به عنوان مثال تعدادی چانک، بین این شاردینگ و تعدادی دیگر برای شاردینگ‌های دیگر. جدول زیر نحوه توزیع 4 چانک را نشان میدهد:

D:\Program Files\MongoDB\Server\3.4\bin>mongodump --db "publisher" --collection books --out "D:\mydumps"
2017-03-04T21:23:04.615+0330    writing publisher.books to
2017-03-04T21:23:04.637+0330    done dumping publisher.books (7 documents)

D:\Program Files\MongoDB\Server\3.4\bin>mongodump

mongorestore "D:\mydumps"

mongorestore "D:\mydumps\publisher\books.bson" --db publisher -c books

mongorestore

D:\Program Files\MongoDB\Server\3.4\bin>mongoexport -d publisher -c books -f Title,ISBN --csv -o D:\temp\books.csv
2017-03-04T22:50:20.671+0330    csv flag is deprecated; please use --type=csv instead
2017-03-04T22:50:20.673+0330    connected to: localhost
2017-03-04T22:50:20.673+0330    exported 7 records

D:\Program Files\MongoDB\Server\3.4\bin>mongoimport -d publisher -c books -f Title,ISBN --type csv D:\temp\books.csv
2017-03-04T23:05:50.588+0330    connected to: localhost
2017-03-04T23:05:50.591+0330    imported 8 documents

public class Book:Entity
    {
        public string Title { get; set; }
        public string ISBN { get; set; }
        public int Price { get; set; }
        public List<Author> Authors { get; set; }
        public BsonDocument ExtraFields { get; set; }
        public Language Language { get; set; }
        public ObjectId Image { get; set; }
        public int Year { get; set; }
        public DateTime LastStock { get; set; }

    }

     var book = new Book()
            {
                Title = "Gone With Wind",
                ISBN = "43442424",
                Price = 50000,
                Year = 1936,
                LastStock = DateTime.Now.AddDays(-13),
                Language = new Language()
                {
                    Name = "Persian"
                },
                Authors = new List<Author>()
               {
                   new Author()
                   {
                       Name = "Margaret Mitchell"
                   }
               },
                ExtraFields=new BsonDocument("Translator", "Ali Mahboobi")
            };

همینطور که می‌بینید این فیلد جدید به عنوان یک شیء جدا یا یک سند توکار ذخیره شده‌است. ولی اگر میخواهید به عنوان یک فیلد، همانند دیگر فیلدها ذخیره شود، باید فیلد ExtraField را به ویژگی BsonExtraElement مزین کنید. پس مدل را به شکل زیر بازنویسی میکنیم:

public class Book:Entity
    {
        public string Title { get; set; }
        public string ISBN { get; set; }
        public int Price { get; set; }
        public List<Author> Authors { get; set; }
        [BsonExtraElements]
        public BsonDocument ExtraFields { get; set; }
        public Language Language { get; set; }
        public ObjectId Image { get; set; }
        public int Year { get; set; }
        public DateTime LastStock { get; set; }

    }

public class Location   
{ 
     public string City { get; set; } 
     public string State { get; set; } 
     public Location(string city, string state) 
     { 
           City = city; 
           State = state; 
     } 
}

 var location = new Location("Lake Charles","LA");

 var location = new Tuple<string,string>("Lake Charles","LA");   
// Print out the address
var address = $"{location.Item1}, {location.Item2}";

static Tuple<int, string, string> GetHumanData()
{
   return Tuple.Create(10, "Marcus", "Miller");
}

 var data = GetHumanData();
Console.WriteLine("What is this value {0} or this {1}",  data.Item1, data.Item3);

(int x1, string s1) = (3, "one");
Console.WriteLine($"{x1} {s1}");

 error CS8179: Predefined type 'System.ValueTuple`2' is not defined or imported

 PM> install-package System.ValueTuple

int x2;
string s2;
(x2, s2) = (42, "two");
Console.WriteLine($"{x2} {s2}");

static (int, int) Divide(int x, int y)
{
   int result = x / y;
   int reminder = x % y;
   return (result, reminder);
}

 (int result, int reminder) = Divide(11, 3);
Console.WriteLine($"{result} {reminder}");

 (var result1, var reminder1) = Divide(11, 3);
Console.WriteLine($"{result1} {reminder1}");

 var (result1, reminder1) = Divide(11, 3);

static (int, string, string) GetHumanData()
{
   return (10, "Marcus", "Miller");
}

 (int Age, string FirstName, string LastName) results = GetHumanData();
Console.WriteLine(results.Age);
Console.WriteLine(results.FirstName);
Console.WriteLine(results.LastName);

 ValueTuple<int, int> tuple1 = Divide(11, 3);

 (int, int) n = (1,1);
System.Console.WriteLine(n.Item1);

 ValueTuple<int, int> n = new ValueTuple<int, int>(1, 1);
System.Console.WriteLine(n.Item1);

 (int,int,int,int,int,int,int,(int,int))

 var tuple2 = ("Stephanie", 7);
Console.WriteLine($"{tuple2.Item1}, {tuple2.Item2}");

 var tuple3 = (Name: "Matthias", Age: 6);
Console.WriteLine($"{tuple3.Name} {tuple3.Age}");

static (int radius, double area) CalculateAreaOfCircle(int radius)
{
   return (radius, Math.PI * Math.Pow(radius, 2));
}

 var circle = CalculateAreaOfCircle(2);
Console.WriteLine($"A circle of radius, {circle.radius}," +
 $" has an area of {circle.area:N2}.");

class Person
{    private readonly string _firstName;    private readonly string _lastName;    public Person(string firstname, string lastname)    {        _firstName = firstname;        _lastName = lastname;    }    public override String ToString() => $"{_firstName} {_lastName}";    public void Deconstruct(out string firstname, out string lastname)    {        firstname = _firstName;        lastname = _lastName;    }
}

 var p1 = new Person("Katharina", "Nagel");
(string first, string last) = p1;
Console.WriteLine($"{first} {last}");

public class Rectangle
{    public Rectangle(int height, int width)    {        Height = height;        Width = width;    }    public int Width { get; }    public int Height { get; }
}
public static class RectangleExtensions
{    public static void Deconstruct(this Rectangle rectangle, out int height, out int width)    {        height = rectangle.Height;        width = rectangle.Width;    }
}

 var r1 = new Rectangle(100, 200);
(int height, int width) = r1;
Console.WriteLine($"height: {height}, width: {width}");

List<Employee> allEmployees = new List<Employee>()
{
  new Employee { ID = 1L, Name = "Fred", Salary = 50000M },
  new Employee { ID = 2L, Name = "Sally", Salary = 60000M },
  new Employee { ID = 3L, Name = "George", Salary = 70000M }
};
var wellPaid =
  from oneEmployee in allEmployees
  where oneEmployee.Salary > 50000M
  select new { EmpName = oneEmployee.Name,
               Income = oneEmployee.Salary };

var wellPaid =
  from oneEmployee in allEmployees
  where oneEmployee.Salary > 50000M
  orderby oneEmployee.Salary descending
  select (EmpName: oneEmployee.Name,
          Income: oneEmployee.Salary);
var highestPaid = wellPaid.First().EmpName;

public Task<(int index, T item)> FindAsync<T>(IEnumerable<T> input, Predicate<T> match)
{
   var dictionary = new Dictionary<(int, int), string>();
   throw new NotSupportedException();
}

public class User
{    public User(string name)    {        Name = name;    }    public string Name { get; }
}


object[] data = { null, 42, new User("User 1"), new User("User 2") };
foreach (var item in data)
{    if (item is null) Console.WriteLine("it's a const pattern");    if (item is 42) Console.WriteLine("it's 42");
}

object[] data = { null, 42, new User("User 1"), new User("User 2") };
foreach (var item in data)
{    if (item is int i) Console.WriteLine($"it's a type pattern with an int and the value {i}");    if (item is User p) Console.WriteLine($"it's a person: {p.Name}");    if (item is User p2 && p2.Name.StartsWith("U"))    {        Console.WriteLine($"it's a person starting with U {p2.Name}");    }
}

object obj1 = "Hello, World!";
var str1 = obj1 as string;
if (str1 != null)
{
   Console.WriteLine(str1);
}

object obj2 = "Hello, World!";
if (obj2 is string str2)
{
   Console.WriteLine(str2);
}

object[] data = { null, 42, new User("User 1"), new User("User 2") };
foreach (var item in data)
{
    if (item is var x) Console.WriteLine($"it's a var pattern with the type {x?.GetType()?.Name}");
}

public static void SwitchPattern(object o)
{    switch (o)    {        case null:            Console.WriteLine("it's a constant pattern");            break;        case int i:            Console.WriteLine("it's an int");            break;        case User p when p.Name.StartsWith("U"):            Console.WriteLine($"a U person {p.Name}");            break;        case User p:            Console.WriteLine($"any other person {p.Name}");            break;        case var x:            Console.WriteLine($"it's a var pattern with the type {x?.GetType().Name} ");            break;        default:            break;    }
}

Select Case age
  Case 50
    ageBlock = "the big five-oh"
  Case 80, 81, 82, 83, 84, 85, 86, 87, 88, 89
    ageBlock = "octogenarian"
  Case 90 To 99
    ageBlock = "nonagenarian"
  Case Is >= 100
    ageBlock = "centenarian"
  Case Else
    ageBlock = "just old"
End Select

string ageBlock;
var age = 40;
switch (age)
{    case 50:        ageBlock = "the big five-oh";        break;    case var testAge when (new List<int> { 80, 81, 82, 83, 84, 85, 86, 87, 88, 89 }).Contains(testAge):        ageBlock = "octogenarian";        break;    case var testAge when ((testAge >= 90) && (testAge <= 99)):        ageBlock = "nonagenarian";        break;    case var testAge when (testAge >= 100):        ageBlock = "centenarian";        break;    default:        ageBlock = "just old";        break;
}

int numericResult;
if (int.TryParse(input, out numericResult))
    WriteLine(numericResult);
else
    WriteLine("Could not parse input");

if (int.TryParse(input, out int result))
    WriteLine(result);
else
    WriteLine("Could not parse input");

if (int.TryParse(input, out var answer))
    WriteLine(answer);
else
    WriteLine("Could not parse input");

if (!int.TryParse(input, out int result))
{    
    return null;
}

return result;

class Program
{
  static void Main(string[] args)
  {
    string firstName;
    string lastName;
    CreateName(out firstName, out lastName);
    Console.WriteLine($"Hello {firstName} {lastName}");
  }
  private static void CreateName(out string firstName, out string lastName)
  {
    firstName = "Kevin";
    lastName = "Griffin";
  }
}

class Program
{
  static void Main(string[] args)
  {   
    CreateName(out string firstName, out string lastName);
    Console.WriteLine($"Hello {firstName} {lastName}");
  }
  private static void CreateName(out string firstName, out string lastName)
  {
    firstName = "Kevin";
    lastName = "Griffin";
  }
}

static void PassByValueSample()
{
    int a = 1;
    PassByValue(a);
    Console.WriteLine($"after the invocation of {nameof(PassByValue)}, {nameof(a)} = {a}");
}
static void PassByValue(int x)
{
    x = 2;
}

static void PassByReferenceSample()
{
    int a = 1;
    PassByReference(ref a);
    Console.WriteLine($"after the invocation of {nameof(PassByReference)}, {nameof(a)} = {a}");
}
static void PassByReference(ref int x)
{
    x = 2;
}

static void OutSample()
{
    Out(out int a);
    Console.WriteLine($"after the invocation of {nameof(Out)}, {nameof(a)} = {a}");
}
static void Out(out int x)
{
    x = 2;
}

if (int.TryParse("42", out var result))
{
   Console.WriteLine($"the result is {result}");
}

 int x = 3;
ref int x1 = ref x;
x1 = 2;
Console.WriteLine($"local variable {nameof(x)} after the change: {x}");

 ref int i = sequence.Count();

 ref int number1 = null; // ERROR
ref int number2 = 42; // ERROR

 static ref int ReturnByReference()
{
    int[] arr = { 1 };
    ref int x = ref arr[0];
    return ref x;
}

static ref int ReturnByReference2()
{
   int[] arr = { 1 };
   return ref arr[0];
}

static ref int ReturnByReference3(ref int x)
{
    x = 2;
    return ref x;
}

class Thing1
{
    ref string _Text1; /* Error */
    ref string Text2 { get; set; } /* Error */
    string _text = "Text";
    ref string Text3 { get { return ref _text; } } // Properties that return a reference are allowed
}

private MyBigStruct[] array = new MyBigStruct[10];
private int current;
public ref MyBigStruct GetCurrentItem()
{
   return ref array[current];
}

public async Task<long> GetDirectorySize(string path, string searchPattern)
{    if (!Directory.EnumerateFileSystemEntries(path, searchPattern).Any())        return 0;    else        return await Task.Run<long>(() => Directory.GetFiles(path, searchPattern,        SearchOption.AllDirectories).Sum(t => (new FileInfo(t).Length)));
}

 AsyncTaskMethodBuilder<long>.Create()

public async ValueTask<long> GetDirectorySize(string path, string searchPattern)
{    if (!Directory.EnumerateFileSystemEntries(path, searchPattern).Any())        return 0;    else        return await Task.Run<long>(() => Directory.GetFiles(path, searchPattern,        SearchOption.AllDirectories).Sum(t => (new FileInfo(t).Length)));
}

 PM> install-package System.Threading.Tasks.Extensions

[Flags]
public enum Option
{
None = 0x00,
Option1 = 0x01,
Option2 = 0x02,
Option3 = 0x04,
Option4 = 0x08,
Option5 = 0x10,
Option6 = 0x20,
Option7 = 0x40,
Option8 = 0x80,
All = 0xFF
}

<img [src]="...." />

<img [ngClass]='..' />

<span appHighlight>Attibute Directive</span>

public class MyApiType
{    private object _loadedResource;    private object _someProperty;    public MyApiType()    {        _loadedResource = LoadResource();        if (_loadedResource == null) throw new InvalidOperationException();    }    public object SomeProperty    {        get        {            return _someProperty;        }        set        {            if (value == null) throw new ArgumentNullException();            _someProperty = value;        }    }
}

public class MyApiType
{    private object _loadedResource = LoadResource() ?? throw new InvalidOperationException();    private object _someProperty;    public object SomeProperty    {        get        {            return _someProperty;        }         set        {            _someProperty = value ?? throw new ArgumentNullException();        }    }
}

public class MyApiType
{    private object _loadedResource = LoadResource() ?? throw new InvalidOperationException();    private object _someProperty;    public object SomeProperty    {        get => _someProperty;        set => _someProperty = value ?? throw new ArgumentNullException();    }
}

public partial class ShippingAddressPage
{    private readonly IWebDriver driver;    public ShippingAddressPage(IWebDriver driver)    {        if (driver == null)        {            throw new ArgumentNullException(nameof(driver));        }        this.driver = driver;    }
}

public partial class ShippingAddressPage
{    private readonly IWebDriver driver;    public ShippingAddressPage(IWebDriver driver) =>      this.driver = driver ?? throw new ArgumentNullException(nameof(driver));
}

private static int ThrowUsageInAnExpression(int value = 40)
{
    return value < 20 ? value : throw new ArgumentOutOfRangeException("Argument value must be less than 20");
}