static void Main(string[] args)
{
var books = new BookRepository().GetBooks();
//LINQ Query Operators
var listBooks2 =
from b in books
where b.Price < 10
orderby b.Title
select b.Title;
//LIQN Extension Methods
var listBooks = books
.Where(b => b.Price < 10)
.OrderBy(b => b.Title)
.Select(b => b.Title);
var book1 = books.SingleOrDefault(b => b.Title == "ASP.NET");
var book2 = books.FirstOrDefault(b => b.Title == "C# Advanced Topics");
var book3 = books.LastOrDefault(b => b.Title == "C# Advanced Topics");
var book4 = books.Skip(2).Take(3);
var book5 = books.Count();
var book6 = books.Max(b => b.Price);
var book7 = books.Min(b => b.Price);
var book8 = books.Sum(b => b.Price);
var book9 = books.Average(b => b.Price);
System.Console.WriteLine(book9);
}
static void Main(string[] args)
{
var books = new BookRepository().GetBooks();
//without linq
//var cheapBooks = new List<Book>();
//foreach (var book in books)
//{
// if (book.Price < 10)
// cheapBooks.Add(book);
//}
//with linq Extension methods:
var cheapBooks = books.Where(b => b.Price < 10).OrderBy(b => b.Title); //can chain linq!
//.Select is used for "projections" or "transformations".
//the below code transforms a list of books into a list of strings.
var cheapBooksTitleString = books.Select(b => b.Title);
//more reader-friendly layout:
var readerFriendly = books
.Where(b => b.Price < 10)
.OrderBy(b => b.Title)
.Select(b => b.Title);
foreach (var book in cheapBooks)
{
Console.WriteLine($"{book.Title}, {book.Price}");
}
//with LINQ query Operators:
var cheaperBooks = from b in books
where b.Price < 10
orderby b.Title
select b.Title;
//============
//other LINQ methods
var single = books.Single(b => b.Title == "Book 3"); //if it can't find, it will crash. It wants one and only one object, if you're not sure better to use...
Console.WriteLine(single.Title);
var singleOrDefault = books.SingleOrDefault(b => b.Title == "hmm doesnt exist"); //returns null if it can't find, better to avoid exception crashing
Console.WriteLine(singleOrDefault == null);
var first = books.First(); //gives first book
var firstWithPredicate = books.First(b => b.Title == "Book 4"); //gives first book with that title, i.e. the one with price as $14.
Console.WriteLine(firstWithPredicate.Price);
var firstOrDefault = books.FirstOrDefault(b => b.Title == "Book 08089"); //if nothing matches the lambda condition, it returns null without throwing exception
var last = books.Last();
var lastOrDefault = books.LastOrDefault();
var skip = books.Skip(2).Take(3); //this will skip the first 2, and take the next 3 to the new list.
Console.WriteLine($"Skip:");
foreach (var book in skip)
{
Console.WriteLine(book.Title);
}
var count = books.Count(); //will be 5
var max = books.Max(b => b.Price); //what does max mean? in this case, highest price.
Console.WriteLine(max); //this is the price itself.
var min = books.Min(b => b.Price);
Console.WriteLine(min);
var sum = books.Sum(b => b.Price); //sum based on price of books
Console.WriteLine(sum);
var averagePrice = books.Average(b => b.Price);
Console.WriteLine(averagePrice); //float!
}
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)
{
//Language Integrated Query
var books = new BookRepository().GetBooks();
//var cheaperBooks = new List<Book>();
//foreach (var book in books)
//{
// if (book.Price < 10)
// cheaperBooks.Add(book);
//}
//Linq Query Operators - bu kısım aslında arka planda Linq Extension Methods translate edilir
var cheaperBooks =
from b in books
where b.Price < 10
orderby b.Title
select b.Title;//select b;
//Linq Extension Methods
var cheapBooks = books
.Where(b => b.Price < 10)
.OrderBy(b => b.Title)
.Select(b => b.Title);
foreach (var book in cheapBooks)
Console.WriteLine(book);
//Console.WriteLine(book.Title + " " + book.Price);
Console.ReadLine();
//var bookItem = books.Single(b => b.Title == "ASP.NET MVC++"); //null gelirse exception fırlatır
//var bookItem = books.SingleOrDefault(b => b.Title == "ASP.NET MVC++");//null gelme ihtimali varsa kullanılır
//var bookItem = books.First(b => b.Title == "C# Advanced Topics");
//var bookItem = books.FirstOrDefault(b => b.Title == "C# Advanced Topics");
var bookItem = books.LastOrDefault(b => b.Title == "C# Advanced Topics");
Console.WriteLine(bookItem.Title + " " + bookItem.Price);
Console.ReadLine();
//Good for paging
var pagedBooks = books.Skip(2).Take(3);
foreach (var book in pagedBooks)
{
Console.WriteLine(book.Title + " " + book.Price);
}
Console.ReadLine();
var count = books.Count();
Console.WriteLine(count);
Console.ReadLine();
var maxPrice = books.Max(b => b.Price);
Console.WriteLine(maxPrice);
var minPrice = books.Min(b => b.Price);
Console.WriteLine(minPrice);
var totalPrice = books.Sum(b => b.Price);
Console.WriteLine(totalPrice);
var averagePrice = books.Average(b => b.Price);
Console.WriteLine(averagePrice);
Console.ReadLine();
}
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();
// LINQ Query Operators
// var cheaperBooks =
// from b in books
// where b.Price < 10
// orderby b.Title
// select b.Title;
books.Single(b => b.Title == "ASP.NET MVC"); // one object
books.SingleOrDefault(b => b.Title == "ASP.NET MVC++"); //no books match this condition, function returns null
Console.WriteLine(books == null);
var book = books.First(b => b.Title == "C# Advanced Topics"); // First which match
books.FirstOrDefault(b => b.Title == "C# Advanced Topics"); // null if no books match
books.Last(b => b.Title == "C# Advanced Topics");
books.LastOrDefault(b => b.Title == "C# Advanced Topics"); // null if no books match
var pagedBooks = books.Skip(2).Take(3); // skip 2 object and take 3
foreach (var pagedBook in pagedBooks)
{
Console.WriteLine(pagedBook.Title);
}
var countOfBooks = books.Count();
var maxPrice = books.Max(b => b.Price);
var minPrice = books.Min(b => b.Price);
var totalPrices = books.Sum(b => b.Price);
// books.Where() <- to filter and retun a list of books to match to a given condition
// books.Single() <- to filter and return a one book
// books.SingleOrDefault() <- if don't find book return null
// books.First()
// books.FirstOrDefault()
// books.Last()
// books.LastOrDefault()
// books.Min()
// books.Max()
// books.Count()
// books.Sum()
// books.Average(b => b.Price)
// books.Skip(5).Take(3)
// LINQ Extension Methods
// var cheapBooks = books
// .Where(b => b.Price < 10)
// .OrderBy(b => b.Title)
// .Select(b => b.Title);
// foreach (var book in cheapBooks)
// {
// Console.WriteLine(book);
// }
}
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)
{
//Language Integrated Query
var books = new BookRepository().GetBooks();
//var cheaperBooks = new List<Book>();
//foreach (var book in books)
//{
// if (book.Price < 10)
// cheaperBooks.Add(book);
//}
//Linq Query Operators - bu kısım aslında arka planda Linq Extension Methods translate edilir
var cheaperBooks =
from b in books
where b.Price < 10
orderby b.Title
select b.Title;//select b;
//Linq Extension Methods
var cheapBooks = books
.Where(b => b.Price < 10)
.OrderBy(b => b.Title)
.Select(b => b.Title);
foreach (var book in cheapBooks)
{
Console.WriteLine(book);
}
//Console.WriteLine(book.Title + " " + book.Price);
Console.ReadLine();
//var bookItem = books.Single(b => b.Title == "ASP.NET MVC++"); //null gelirse exception fırlatır
//var bookItem = books.SingleOrDefault(b => b.Title == "ASP.NET MVC++");//null gelme ihtimali varsa kullanılır
//var bookItem = books.First(b => b.Title == "C# Advanced Topics");
//var bookItem = books.FirstOrDefault(b => b.Title == "C# Advanced Topics");
var bookItem = books.LastOrDefault(b => b.Title == "C# Advanced Topics");
Console.WriteLine(bookItem.Title + " " + bookItem.Price);
Console.ReadLine();
//Good for paging
var pagedBooks = books.Skip(2).Take(3);
foreach (var book in pagedBooks)
{
Console.WriteLine(book.Title + " " + book.Price);
}
Console.ReadLine();
var count = books.Count();
Console.WriteLine(count);
Console.ReadLine();
var maxPrice = books.Max(b => b.Price);
Console.WriteLine(maxPrice);
var minPrice = books.Min(b => b.Price);
Console.WriteLine(minPrice);
var totalPrice = books.Sum(b => b.Price);
Console.WriteLine(totalPrice);
var averagePrice = books.Average(b => b.Price);
Console.WriteLine(averagePrice);
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);
* }
* }*/
//LINQ Query Operators Syntax for more clean
var cheaperBooks = from b in books
where b.Price < 10
orderby b.Title
select b;
var cheaperBookTitles = from b in books
where b.Price < 10
orderby b.Title
select b.Title;
//LINQ Extension Methods Syntax for more in depth
var cheapBooks = books
.Where(b => b.Price < 10)
.OrderBy(b => b.Title);
var cheapBookTitles = books
.Where(b => b.Price < 10)
.OrderBy(b => b.Title)
.Select(b => b.Title);
//books.OrderBy(b => b.Title);
foreach (var book in cheapBooks)
{
Console.WriteLine(book.Title + " " + book.Price);
}
Console.WriteLine();
foreach (var book in cheapBookTitles)
{
Console.WriteLine(book);
}
Console.WriteLine();
var bookOne = books.Single(b => b.Title == "ASP.NET MVC");
Console.WriteLine(bookOne.Title + " " + bookOne.Price);
Console.WriteLine();
var bookTwo = books.SingleOrDefault(b => b.Title == "ASP.NET MVC++");
if (bookTwo == null)
{
Console.WriteLine("null");
}
else
{
Console.WriteLine(bookTwo.Title + " " + bookTwo.Price);
}
Console.WriteLine();
var bookThree = bookTwo == null?("null"): (bookTwo.Title + " " + bookTwo.Price);
Console.WriteLine(bookThree);
Console.WriteLine();
var bookFour = books.FirstOrDefault(b => b.Title == "C# Advanced Topics");
var bookFive = bookFour == null ? ("null") : (bookFour.Title + " " + bookFour.Price);
Console.WriteLine(bookFive);
Console.WriteLine();
var bookSix = books.LastOrDefault(b => b.Title == "C# Advanced Topics");
var bookSeven = bookSix == null ? ("null") : (bookSix.Title + " " + bookSix.Price);
Console.WriteLine(bookSeven);
Console.WriteLine();
var pagedBooks = books.Skip(2).Take(3);
foreach (var book in pagedBooks)
{
Console.WriteLine(book.Title + " " + book.Price);
}
Console.WriteLine();
var count = books.Count();
Console.WriteLine(count + " books");
Console.WriteLine();
var max = books.Max(b => b.Price);
Console.WriteLine("$" + max);
Console.WriteLine();
var min = books.Min(b => b.Price);
Console.WriteLine("$" + min);
Console.WriteLine();
var sum = books.Sum(b => b.Price);
Console.WriteLine("$" + sum);
Console.WriteLine();
var avg = books.Average(b => b.Price);
Console.WriteLine("$" + avg);
//Func<int, int, int> add = (a, b) => a + b;
//Console.WriteLine(add(2, 3));
}
