Esempio n. 1
0
        static void Main(string[] args)
        {
            var people = new List <Person>()
            {
                new Person()
                {
                    Name = "Anastasia", Job = "Developer"
                },
                new Person()
                {
                    Name = "Dzmitry", Job = "Developer"
                },
                new Person()
                {
                    Name = "Peter", Job = "Bookeeper"
                },
                new Person()
                {
                    Name = "Josh", Job = "Cook"
                },
                new Person()
                {
                    Name = "Aaron", Job = "Cook"
                },
                new Person()
                {
                    Name = "Anastasia", Job = "Server"
                },
            };

            var anastasias = from p in people
                             where p.Job == "Developer"
                             select p;

            foreach (var anastasia in anastasias)
            {
                Console.WriteLine(anastasia.Job);
                Console.WriteLine(anastasia.Name);
            }



            var books = new BookRepository().GetBooks();


            //With select you can select by property
            var cheapBooksTitles = books
                                   .Where(b => b.Price < 10)
                                   .Where(b => b.Price < 10)
                                   .Select(b => b.Title);

            // Linq query Operator like a SQL
            var cheaperBooks = from b in books
                               where b.Price < 10
                               orderby b.Title
                               select b.Title;

            // Returning Single Book or Operator || SingleOrDefault will return null as a value
            var singleBook = books.SingleOrDefault(b => b.Title == "ASP.NET MVC");

            Console.WriteLine(singleBook.Price);

            // can find the first value that matche the query || FirstOrDefalult
            Console.WriteLine(books.First(b => b.Title == "C# Advanced Topics").Title);

            // Last || LastOrDefault
            Console.WriteLine(books.Last(b => b.Title == "C# Advanced Topics").Title);

            // Skiping the data
            Console.WriteLine(books.Skip(2).Take(3).Select(b => b.Title));

            // Aggregators
            Console.WriteLine("Aggregators");
            Console.WriteLine(books.Count());

            //Max Price
            Console.WriteLine(books.Max(x => x.Price));

            // Cheppest Price
            Console.WriteLine(books.Min(x => x.Price));

            // Sum
            Console.WriteLine(books.Sum(b => b.Price));

            // Aggregate fuinctions
            var list = new List <int>()
            {
                13, 18, 25, 12, 16
            };

            list.Aggregate((a, b) => a + b);

            // Get Avarage
            var avgPrice = books.Average(b => b.Price);

            Console.WriteLine("The avarage book price is {0} ", avgPrice);


            foreach (var s in books.Skip(2).Take(3).Select(b => b.Title))
            {
                Console.WriteLine("Skipped Book {0} ", s);
            }


            foreach (var cheapBooksTitle in cheapBooksTitles)
            {
                Console.WriteLine(cheapBooksTitle);
            }



            foreach (var book in books.OrderBy(b => b.Title).Where(b => b.Price < 10))
            {
                Console.WriteLine(book.Title);
                Console.WriteLine(book.Price);
            }
        }
Esempio n. 2
0
        static void Main(string[] args)
        {
            var books = new BookRepository().GetBooks();

            //LINQ Query Operators
            var cheaperBooks = from b in books
                               where b.Price < 10
                               orderby b.Title
                               select b.Title;

            /*---the same -----*/

            //LINQ Extension Methods
            var cheapBooks = books
                             .Where(b => b.Price < 10)
                             .OrderBy(b => b.Title)
                             .Select(b => b.Title);

            foreach (var bk in cheapBooks)
            {
                // Console.WriteLine(book.Title);
                Console.WriteLine(bk);
            }


            /*------------------------------------------------------------------*/
            var book  = books.Single(b => b.Title == "ASP.NET MVC");            //throw an exception if nothing found
            var book2 = books.SingleOrDefault(b => b.Title == "ASP.NET MVC++"); //return null if nothing found

            Console.WriteLine(book.Title);
            Console.WriteLine(book2 == null ? "null" : book2.Title);

            /*-------------------------------------------------------------------*/

            var book3 = books.First();                                     //first element of the collection
            var book4 = books.First(b => b.Title == "C# Advanced Topics"); //first element of the collection
            var book5 = books.FirstOrDefault();                            //return null if nothing found

            Console.WriteLine(book3.Title);
            Console.WriteLine(book4.Price);
            Console.WriteLine(book5 == null ? "null" : book5.Title);

            var book6 = books.Last();                                     //first element of the collection
            var book7 = books.Last(b => b.Title == "C# Advanced Topics"); //first element of the collection
            var book8 = books.LastOrDefault();                            //return null if nothing found

            Console.WriteLine(book6.Title);
            Console.WriteLine(book7.Price);
            Console.WriteLine(book8 == null ? "null" : book8.Title);

            /*-------------------------------------------------------------------*/

            var books9 = books.Skip(2).Take(3); //used for paging data

            //skip 2 records or two objects and take 3
            foreach (var bb in books9)
            {
                Console.WriteLine(bb.Title);
            }


            /* --------------------------------------------------------------------*/

            var count = books.Count();

            Console.WriteLine(count);

            var maxPrice          = books.Max(b => b.Price);
            var minPrice          = books.Min(b => b.Price);
            var sumPriceofAllBook = books.Sum(b => b.Price);
            var average           = books.Average(b => b.Price);

            Console.WriteLine("maxPrice : {0} and min price : {1} and sum of all books : {2}, and finally average = {3}", maxPrice, minPrice, sumPriceofAllBook, average);

            Console.ReadLine();
        }