static void Main(string[] args)
{
var books = new BookRepository().GetBooks();
//LINQ Extensions Methods
var cheapBooks = books
.Where(b => b.Price < 10);
var cheapBooksOrderedByTitle = books
.Where(b => b.Price < 10)
.OrderBy(b => b.Title);
var stringListOfcheapBooksOrderedByTitle = books
.Where(b => b.Price < 10)
.OrderBy(b => b.Title)
.Select(b => b.Title);
//Fin LINQ Extensions Methods
//LINQ Query Operators, this always start with "from" and always finish with the "select"
var cheaperBooks = from b in books
where b.Price < 10
orderby b.Title
select b.Title;
//Fin LINQ Query Operators
//LINQ Extensions Methods, this method goes to an error if there is not any book with that title
//to avoid it we can use "SingleOrDefault" line 40
var book = books.Single(b => b.Title == "ASP.NET MVC");
//If there is not object matching this condition the Default value will be return which in this case would be null
var book1 = books.SingleOrDefault(b => b.Title == "ASP.NET MVC++");
//These are used for paging data, this means skip to record/object and takes three
var bookList = books.Skip(2).Take(3);
foreach (var pagedBook in bookList)
{
Console.WriteLine(pagedBook.Title);
}
var priceOfMoreExpensiveBook = books.Max(b => b.Price);
var priceOfCheapestBook = books.Min(b => b.Price);
var totalPrices = books.Sum(b => b.Price);
var averages = books.Average(b => b.Price);
}
static void Main(string[] args)
{
var books = new BookRepository().GetBooks();
var cheapBooks = books.Where(b => b.Price < 10);
// LINQ Query Operator
var cheaperBooks =
from b in books
where b.Price < 10
orderby b.Title
select b.Title;
// LINQ Methods can be chained
var orderedByTitle = books
.OrderBy(b => b.Title)
.Select(b => b.Title);
foreach (var b in orderedByTitle)
{
Console.WriteLine(b);
}
// Other Examples
var result1 = books.Single(book => book.Title == "A");
var result2 = books.SingleOrDefault(b => b.Title == "A");
var result3 = books.FirstOrDefault(b => b.Title == "A");
var result4 = books.LastOrDefault(b => b.Title == "A");
var result5 = books.Skip(2).Take(3);
var result6 = books.Count();
var result7 = books.Max(b => b.Price);
var result8 = books.Sum(b => b.Price);
var result9 = books.Average(b => b.Price);
Console.ReadLine();
}
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);
}
}
static void Main(string[] args)
{
var books = new BookRepository().GetBooks();
//LINQ Query Operators
//slightly worse, keywords translate to extension methods
//anyway, and there isnt a keyword for everything. although it is
//friendlier and cleaner.
var cheaperBooks =
from b in books
where b.Price < 10
orderby b.Title
select b;
//LINQ Extension Methods
var cheapBooks = books
.Where(b => b.Price < 10)
.OrderBy(b => b.Title)
.Select(b => b.Title);
var bookMVC = books.FirstOrDefault(b => b.Title == "C# Advanced Topics");
//var bookMVC = books.LastOrDefault(b => b.Title == "C# Advanced Topics");
//var bookMVC = books.SingleOrDefault(b => b.Title == "ASP.NET MVC+");
if (bookMVC != null)
{
Console.WriteLine(bookMVC.Title + " " + bookMVC.Price);
}
Console.WriteLine("---------------------");
Console.WriteLine("Now trying skip and take");
Console.WriteLine("---------------------");
var pagedBooks = books.Skip(2).Take(3);
foreach (var pagedBook in pagedBooks)
{
Console.WriteLine(pagedBook.Title);
}
var count = books.Count();
Console.WriteLine("---------------------");
Console.WriteLine(count);
var max = books.Max(b => b.Price);
Console.WriteLine("---------------------");
Console.WriteLine(max);
var min = books.Min(b => b.Price);
Console.WriteLine("---------------------");
Console.WriteLine(min);
var totalCost = books.Sum(b => b.Price);
Console.WriteLine("---------------------");
Console.WriteLine(totalCost);
var average = books.Average(b => b.Price);
Console.WriteLine("---------------------");
Console.WriteLine(average);
//Workaround, non-LINQ version
//
//var cheapBooks = new List<Book>();
//foreach (var book in books)
//{
// if (book.Price < 10)
// cheapBooks.Add(book);
//}
//foreach (var book in cheapBooks)
//{
// Console.WriteLine("---------------------");
// Console.WriteLine(book.Title + " " + book.Price);
// Console.WriteLine(book);
}
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();
}
