static void Main(string[] args)
{
var books = new BookRepository().GetBooks();
// LINQ Query Operators [always start with the from and end with select]
var cheaperBooks = from b in books
where b.Price < 10
orderby b.Title
select b.Title;
// With 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.Title + " " + book.Price);
Console.WriteLine(book);
}
// SINGLE OBJECT
var book1 = books.SingleOrDefault(books => books.Title == "ASP.NET MVC");
Console.WriteLine(book1.Title);
// first object
var book2 = books.First(b => b.Title == "How to code");
Console.WriteLine(book2.Title + " " + book2.Price);
// last
var book3 = books.LastOrDefault(books => books.Title == "ASP.NET MVC");
Console.WriteLine(book3.Title + " " + book3.Price);
// skip
var pagedBooks = books.Skip(2).Take(3);
Console.WriteLine("\nLast 3 books: ");
foreach (var pageBook in pagedBooks)
{
Console.WriteLine(pageBook.Title);
}
// count
Console.WriteLine($"There are {books.Count()} books. ");
Console.WriteLine($"The highest priced book is P{books.Max(b => b.Price)}");
}
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)
{
//Another example
//Worker work = new Worker();
#region LINQExample1
var books = new BookRepository().GetBooks();
//LINQ Query Operators
var cheaperBooks = from b in books
where b.Price < 10
orderby b.Title
select b.Title;
//Use link instead of the below code
/*var cheapBooks = new List<Book>();
* //foreach(var book in books)
* //{
* // if (book.Price < 10)
* // cheapBooks.Add(book);
* }*/
//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);
#endregion
//will generate an error if item not found
var book = books.Single(b => b.Title == "ASP.NET MVC");
//Will return Null
var bookz = books.SingleOrDefault(b => b.Title == "ASP.NET MVC");
//Gets the first item with the indicated value
//var bookzz = books.First(b => b.Title == "C# Advanced Topics");
var bookzz = books.FirstOrDefault(b => b.Title == "C# Advanced Topics");
var bookzzz = books.Skip(2).Take(3);
Console.WriteLine(book.Title);
}
//Lesson 6 : LINQ
static void Main(string[] args)
{
//LINQ Extension Methods
var books = new BookRepository().GetBooks();
var cheapBooks = books.Where(x => x.Price < 10).Select(x => x.Title);
foreach (var book in cheapBooks)
{
//Console.WriteLine(book.Title);
Console.WriteLine(book);
}
//LINQ Queries
var cheapBooks2 = from b in books
where b.Price < 10
select b.Title;
foreach (var book in cheapBooks2)
{
//Console.WriteLine(book.Title);
Console.WriteLine(book);
}
Console.WriteLine("-----------");
//Return a single book
//var singleBook = books.Single(b => b.Title == "Title 3");
var singleBook = books.SingleOrDefault(b => b.Title == "Title 3");
Console.WriteLine(singleBook.Title);
//Skip data
Console.WriteLine("-----------");
var chosenBooks = books.Skip(2);
foreach (var book in chosenBooks)
{
Console.WriteLine(book.Title);
}
}
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 books = new BookRepository().GetBooks();
var specificBook = books.Single(x => x.Title == "Book1");
var specificBook1 = books.SingleOrDefault(x => x.Title == "Book4");
if (specificBook1 == null)
{
Console.WriteLine("Not Found!");
}
else
{
Console.WriteLine("Found!");
}
Console.WriteLine(books.First(x => x.Price < 200).Title);
Console.WriteLine(books.FirstOrDefault(x => x.Price < 100) == null);
Console.WriteLine();
var filtered = books.Skip(2).Take(3);
foreach (var item in filtered)
{
Console.WriteLine(item.Title);
}
var book = books.Max(b => b.Price);
Console.WriteLine(book);
var sum = books.Sum(b => b.Price);
Console.WriteLine(sum);
#region LINQ Exampes
//LINQ Query
//var cheap = from b in books
// where b.Price < 200
// orderby b.Price
// select b.Price;
//Console.WriteLine();
//foreach (var item in cheap)
//{
// Console.WriteLine(item);
//}
//Console.WriteLine();
//LINQ Extensions
//var cheapBooks = books.Where(x => x.Price < 200);
//var titles = books
// .Where(x => x.Price < 200)
// .Select(x => x.Title);
//cheapBooks
// .OrderBy(x => x.Price);
//PrintList<Book>(books);
//PrintList<Book>(cheapBooks);
//Console.WriteLine();
//foreach (var item in titles)
//{
// Console.WriteLine(item);
//}
#endregion
}
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
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();
}
static void Main(string[] args)
{
var books = new BookRepository().GetBooks();
/*
* This can be done in one line using LINQ:
* var cheapBooks = new List<Book>();
*
* foreach(var book in books)
* {
* if(book.Price < 10)
* {
* cheapBooks.Add(book);
* }
* }
*/
// LINQ Extension methods
var cheapBooks = books
.Where(b => b.Price < 10)
.OrderBy(b => b.Price)
.Select(b => b.Title);
// LINQ Query operators
var cheaperBooks = from b in books
where b.Price < 10
orderby b.Title
select b.Title;
foreach (var book in cheapBooks)
{
//Console.WriteLine(book.Title + " " + book.Price);
Console.WriteLine(book);
}
Console.WriteLine();
foreach (var book in cheaperBooks)
{
//Console.WriteLine(book.Title + " " + book.Price);
Console.WriteLine(book);
}
Console.WriteLine();
var book1 = books.SingleOrDefault(b => b.Title == "ASP.NET MVC+");
Console.WriteLine(book1);
var book2 = books.FirstOrDefault(b => b.Title == "C# Advanced Topics");
Console.WriteLine(book2.Title + " " + book2.Price);
var book3 = books.LastOrDefault(b => b.Title == "C# Advanced Topics");
Console.WriteLine(book3.Title + " " + book3.Price);
Console.WriteLine();
var books4 = books.Skip(2).Take(3);
foreach (var book in books4)
{
Console.WriteLine(book.Title);
}
Console.WriteLine();
var count = books.Count();
Console.WriteLine(count);
Console.WriteLine();
var maxPrice = books.Max(b => b.Price);
Console.WriteLine(maxPrice);
Console.WriteLine();
var minPrice = books.Min(b => b.Price);
Console.WriteLine(minPrice);
Console.WriteLine();
var totalPrice = books.Sum(b => b.Price);
Console.WriteLine(totalPrice);
}
static void Main(string[] args)
{
var books = new BookRepository().GetBooks();
// LINQ query operators
// always start with from and end with select
var cheapBooks =
from b in books
where b.Price < 10
orderby b.Title
select b.Title;
foreach (var book in cheapBooks)
{
Console.WriteLine(book);
}
var singleBook = books.SingleOrDefault(b => b.Title == "Book 2"); // if there is no book2 it will return the default which is null
Console.WriteLine("Single book: " + singleBook.Title);
var firstBook = books.FirstOrDefault(b => b.Title == "Book 3");
Console.WriteLine("First book that has title Book 3: " + firstBook.Price); // default is null
var lastBook = books.LastOrDefault(b => b.Title == "Book 3");
Console.WriteLine("Last book that has title Book 3: " + lastBook.Price);
var pages = books.Skip(2).Take(3); // skips the first 2 books and takes the next 3
foreach (var pagedBook in pages)
{
Console.WriteLine(pagedBook.Title);
}
var count = books.Count();
Console.WriteLine("Count: " + count);
var maxPrice = books.Max(b => b.Price); // returns the book with the max price
Console.WriteLine("Max: " + maxPrice);
var sumPrice = books.Sum(b => b.Price);
Console.WriteLine("Total: " + sumPrice);
// 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);*/
// after using select for the title, book is now a string because it returns an
// IEnumerable of just the title of the books. This can no longer be used
/* foreach(var book in cheapBooks)
* Console.WriteLine(book.Title + " " + book.Price);*/
// without LINQ
/* var cheapBooks = new List<Book>();
* foreach(var book in books)
* {
* if (book.Price < 10)
* {
* cheapBooks.Add(book);
* Console.WriteLine(book.Title + " " + book.Price);
* }
* }*/
}