static void Main(string[] args)
{
var books = new BookRepository().GetBooks();
// 1. Display the list of books that are cheaper than 10$
// Without LINQ
//var cheapBooks = new List<Book>();
//foreach(var book in books)
//{
// if(book.Price < 10)
// {
// cheapBooks.Add(book);
// }
//}
// With LINQ
var cheapBooks = books
.Where(b => b.Price < 10) // We use Where to filter collections
.OrderBy(b => b.Title) // We use OrderBy and OrderByDescending to sort collections
.Select(b => b); // We use Select for custom projections or transformations
foreach (var cheapBook in cheapBooks)
{
Console.WriteLine($"{cheapBook.Title}: {cheapBook.Price}");
}
// 2. Display only one book with specific title
var aspnetBook = books.Single(b => b.Title == "ASP.NET MVC"); // We use Single / SingleOrDefault to take only one element from the collection
Console.WriteLine($"Title of book is {aspnetBook.Title} with price of {aspnetBook.Price}$");
// 3. Give me the first book which title is "C# Advanced Topics"
var firstInstanceOfCSharpAdvancedTopics = books.First(b => b.Title == "C# Advanced Topics"); // We use First / FirstOrDefault to take the first element of a collection returned that satisfied a specific predicate
Console.WriteLine($"Title of book is {firstInstanceOfCSharpAdvancedTopics.Title} with price of {firstInstanceOfCSharpAdvancedTopics.Price}$");
// 4. Skip the first two elements and take the next 3
var pagedBooks = books
.Skip(2)
.Take(3); // We use Skip and Take mainly for paging data
foreach (var pagedBook in pagedBooks)
{
Console.WriteLine($"{pagedBook.Title}: {pagedBook.Price}");
}
// 5. Count the number of elements in a collection
var noOfBooks = books.Count();
Console.WriteLine($"Total number of books in collection: {noOfBooks}");
// 6. Return the book with the maximum price
var maxPriceBook = books.Max(b => b.Price);
Console.WriteLine($"Maximum price of book is {maxPriceBook}$");
// 7. Return total sum of prices of books in the collection
var totalSumOfBookPrices = books.Sum(b => b.Price);
Console.WriteLine($"Total sum of prices of books is: {totalSumOfBookPrices}$");
// 8. Group books by title
var groups = books
.GroupBy(b => b.Title)
.Select(g => new
{
Title = g.Key,
Books = g
});
foreach (var group in groups)
{
Console.WriteLine($"Title: {group.Title}");
foreach (var book in group.Books)
{
Console.WriteLine($"\t Book Price: {book.Price}");
}
}
Console.ReadLine();
}