static void Main(string[] args)
{
var books = new BookRepository().GetBooks();
// 1st use of Linq
var cheapBooks = books.Where(b => b.Price < 10);
foreach (var book in cheapBooks)
{
Console.WriteLine("Bookprice < 10 only: " + book.Title + " Price: " + book.Price);
}
// 2nd use of Linq
books.OrderBy(b => b.Title);
foreach (var book in books)
{
Console.WriteLine("Sorted by title: " + book.Title + " " + book.Price);
}
// Chain linqs and select string only
var cheapBooksTitles = books
.Where(b => b.Price < 10)
.OrderBy(b => b.Title)
.Select(b => b.Title); // Select string-only
foreach (var book in cheapBooksTitles)
{
Console.WriteLine("String only : " + book);
}
}
static void Main(string[] args)
{
var books = new BookRepository().GetBooks();
// Searches collection for items with specific conditions
var cheapBooks = books.Where(book => book.Price < 10);
foreach (var book in cheapBooks)
{
Console.WriteLine(book.Title + " " + book.Price);
}
// Sorts items in collection
var orderedBooks = books.OrderBy(b => b.Title);
foreach (var book in orderedBooks)
{
Console.WriteLine(book.Title + " " + book.Price);
}
// Selects all items in collection and projects them by type fields
var selectedBooks = books.Select(b => b.Title);
foreach (var book in selectedBooks)
{
Console.WriteLine(book);
}
// C# common convention layout for multiple inline LINQ statements
var booksLinq = books
.Where(book => book.Price < 10) // Searches collection for items with specific conditions
.OrderBy(b => b.Title) // Sorts items in collection
.Select(b => b.Title); // Selects all items in collection and projects them by type fields
// OR LINQ Query Operators
var booksLinqQuery =
from b in books
where b.Price < 10
orderby b.Title
select b.Title;
// Another useful LINQ Extension Methods
var singleBook = books.SingleOrDefault(b => b.Title == "ASP.NET MVC"); // returns single item or default value
Console.WriteLine(singleBook != null ? singleBook.Title : "There is no such book in collection");
var firstBook = books.FirstOrDefault(b => b.Title == "Entity Framework");
Console.WriteLine(firstBook.Title + " " + firstBook.Price);
var lastBook = books.LastOrDefault(b => b.Title == "Entity Framework");
Console.WriteLine(lastBook.Title + " " + lastBook.Price);
var skipBooks = books.Skip(2).Take(3);
foreach (var skipBook in skipBooks)
{
Console.WriteLine(skipBook.Title);
}
Console.WriteLine("Books count: " + books.Count());
Console.WriteLine("Books max price: " + books.Max(b => b.Price));
Console.WriteLine("Books min price: " + books.Min(b => b.Price));
Console.WriteLine("Sum of all books prices: " + books.Sum(b => b.Price));
Console.WriteLine("Average of all books prices: " + books.Average(b => b.Price));
}
static void Main(string[] args)
{
var books = new BookRepository().GetBooks();
#region One
//LINQ Query operators
var expensiveBooks = from b in books
where b.Price > 10
orderby b.Title
select b.Title;
expensiveBooks.ToList().ForEach(bt => Console.WriteLine(bt));
Console.WriteLine("**********************");
//LINQ extension methods
var cheapBooks = books.Where(b => b.Price <= 10)
.OrderByDescending(b => b.Title)
.Select(b => b.Title)
.ToList();
cheapBooks.ForEach(bt => Console.WriteLine(bt));
Console.WriteLine("**********************");
var orderedBooks = books.OrderBy(b => b.Price).ToList();
orderedBooks.ForEach(b => Console.WriteLine($"{b.Title} - {b.Price}"));
#endregion
Console.WriteLine();
Console.WriteLine("**********************");
Console.WriteLine("**********************");
#region Two
var book = books.SingleOrDefault(b => b.Title == "Title 3++");
if (book != null)
{
Console.WriteLine(book.Title);
}
book = books.FirstOrDefault(b => b.Title.Contains("Title"));
if (book != null)
{
Console.WriteLine(book.Title + " - " + book.Price);
}
book = books.LastOrDefault(b => b.Title.Contains("Title"));
if (book != null)
{
Console.WriteLine(book.Title + " - " + book.Price);
}
var pagedBooks = books.Skip(1).Take(1).ToList();
pagedBooks.ForEach(b => Console.WriteLine($"{b.Title} - {b.Price}"));
#endregion
Console.WriteLine();
Console.WriteLine("**********************");
Console.WriteLine("**********************");
#region Three
var maxPrice = books.Max(b => b.Price);
var minPrice = books.Min(b => b.Price);
Console.WriteLine(maxPrice);
Console.WriteLine(minPrice);
var totalPrices = books.Sum(b => b.Price);
Console.WriteLine(totalPrices);
var averagePrice = books.Average(b => b.Price);
Console.WriteLine(averagePrice);
#endregion
Console.ReadLine();
}
static void Main(string[] args)
{
var books = new BookRepository().GetBooks();
var cheapBooks = new List <Book>();
foreach (var book in books)
{
if (book.Price < 10)
{
cheapBooks.Add(book);
}
}
// ŞİMDİ AYNI FİLTRELEMEYİ LINQ İLE YAPALIM
// LINQ Extension Methods
var cheapBooks1 = books.Where(b => b.Price < 10); // Lambda Expression ve where sorgusu
// orderby kullanalım
var cheapBooks2 = books.OrderBy(b => b.Title);
// ucuca ekleyip, hem fiyata göre filtreleyip, hem Title a gore sıralayalım
var cheapBooks3 = books.Where(b => b.Price < 10).OrderBy(b => b.Title);
// ucuca ekleyip, hem fiyata göre filtreleyip, hem Title a gore sıralayalım. Select ekleyelim.
// select projection veya transformation için kullanılıyormuş
// sadece Title listesi oluştu yani string generic listesi
var cheapBooks4 = books
.Where(b => b.Price < 10)
.OrderBy(b => b.Title)
.Select(b => b.Title);
// (Yukarıdaki şekildeki gibi nokta, altsatırda devam etmeye, LINQ Extension Methods diyoruz.)
// Single ile sadece tek birşey seçebiliriz. Fakat dikkat et, eğer o filtren bulunamazsa, app hata verir önlem de almamışsan
var cheapBooks6 = books.Single(b => b.Title == "ASP.NET MVC");
// O objectin olmaması riski de varsa, SingleOrDefault kullanırız. Alttaki örnekte default olarak null gelir bulunamazsa...
var cheapBooks7 = books.SingleOrDefault(b => b.Title == "ASP.NET MVC++"); // ++ eklediigimiz için bulunamıycak.
// First, aynısından sadece ilkini bulur - bulamazsa hata verir
var cheapBooks8 = books.First(b => b.Title == "C# Advanced Topics");
// FirstOrDefault, ilki, ama hiç bulamazsa default olarak bu örnekte null
var cheapBooks9 = books.FirstOrDefault(b => b.Title == "C# Advanced Topics");
// Last, aynısından sadece sonuncuyu bulur - bulamazsa hata verir
var cheapBooks10 = books.Last(b => b.Title == "C# Advanced Topics");
// LastOrDefault, sonuncusu, ama hiç bulamazsa default olarak bu örnekte null
var cheapBooks11 = books.LastOrDefault(b => b.Title == "C# Advanced Topics");
// Skip() ve Take() - ilk 2 tanesini atla, sonra 3 tanesini al
var cheapBooks12 = books.Skip(2).Take(3);
// SQL deki gibi Aggregate Func da var. mesela Count()
var bookCount = books.Count();
// SQL deki Max() - tabi price a göre max olmasını biz söylüycez - float type a return ediyor, çünkü class Books ta, Price type float
var highestPrice = books.Max(b => b.Price); // type: float
// Min()
var minPrice = books.Min(b => b.Price); // type: float
// Sum() - tüm kitapların fiyatı toplamı
var totalPrice = books.Sum(b => b.Price); // type: float
// Average() - tüm kitapların ortalama fiyatı
var avgPrice = books.Average(b => b.Price); // type: float
foreach (var book in cheapBooks)
{
Console.WriteLine(book.Title + " " + book.Price);
}
foreach (var book in cheapBooks4)
{
Console.WriteLine(book);
}
foreach (var book in cheapBooks12)
{
Console.WriteLine(book.Title + " " + book.Price);
}
// LINQ Query Methods
var cheapBooks5 = from b in books
where b.Price < 10
orderby b.Title
select b.Title;
}
static void Main(string[] args)
{
var books = new BookRepository().GetBooks();
Console.WriteLine("-------------- all books ");
foreach (var book in books)
{
Console.WriteLine($"{book.Title}, {book.Price}");
}
// LINQ Extension Methods
var cheapBooks = books
.Where(b => b.Price < 20)
.OrderBy(b => b.Title);
var cheapBooksStrings = books
.Where(b => b.Price < 20)
.OrderBy(b => b.Title)
.Select(b => b.Title);
Console.WriteLine("-------------- get books (objects) with LINQ Extension Methods");
foreach (var book in cheapBooks)
{
Console.WriteLine($"{book.Title}, {book.Price}");
}
Console.WriteLine("-------------- get titles with LINQ Extension Methods");
foreach (var book in cheapBooksStrings)
{
Console.WriteLine(book);
}
// LINQ Query Operators
var cheapBooksWithQuery =
from b in books
where b.Price < 20
orderby b.Title
select b;
Console.WriteLine("-------------- get books (objects) with LINQ Query Operators");
foreach (var book in cheapBooksWithQuery)
{
Console.WriteLine($"{book.Title}, {book.Price}");
}
var theBook = new Book {
Title = "I dont exist", Price = 0
};
Console.WriteLine("-------------- Single");
theBook = books.SingleOrDefault(b => b.Title == "Zoo");
Console.WriteLine($"{theBook.Title}, {theBook.Price}");
Console.WriteLine("-------------- SingleOrDefault");
theBook = books.SingleOrDefault(b => b.Title == "zoo");
Console.WriteLine(theBook == null);
Console.WriteLine("-------------- First");
theBook = books.FirstOrDefault(b => b.Price == 6.99m);
Console.WriteLine($"{theBook.Title}, {theBook.Price}");
var orderedBooks = books.OrderBy(b => b.Title);
Console.WriteLine("-------------- First of ordered");
theBook = orderedBooks.FirstOrDefault(b => b.Price == 6.99m);
Console.WriteLine($"{theBook.Title}, {theBook.Price}");
Console.WriteLine("-------------- FirstOrDefault");
theBook = books.FirstOrDefault(b => b.Price == 123.99m);
Console.WriteLine(theBook == null);
Console.WriteLine("-------------- Skip, Take");
var pagedBooks = books.Skip(3).Take(4);
foreach (var book in pagedBooks)
{
Console.WriteLine($"{book.Title}, {book.Price}");
}
Console.WriteLine("-------------- Count");
Console.WriteLine($"there are {books.Count} books");
Console.WriteLine("-------------- Sum");
Console.WriteLine($"you need {books.Sum(b => b.Price)} dollars to buy all the books");
}
