static void Main(string[] args)
{
//args => expression
//number => number*number;
// ()=> ...//eğer hiç arguman olmayacak ise
// x => ... //tek argüman alacak ise
// (x,y,z) => ..... //birden çok argüman alacak ise
Func<int, int> square = number => number * number; //Square;
Console.WriteLine(square(5));
//Console.WriteLine(Square(5));
//Console.ReadLine();
//Lambda içinde aynı scope içinde başka değişkende kullanılabilir (factor) gibi
const int factor = 5;
Func<int, int> multipler = n => n * factor;
var result = multipler(10);
Console.WriteLine(result);
//Console.ReadLine();
var books = new BookRepository().GetBooks();
//var cheapBooks = books.FindAll(IsCheaperThan10Dollars); //predicate method ile kullanımı
var cheapBooks = books.FindAll(b => b.Price < 10); //LambdaExpression hali
foreach (var book in cheapBooks)
{
Console.WriteLine(book.Title);
}
Console.ReadLine();
}
static void Main(string[] args)
{
var books = new BookRepository().GetBooks();
var cheapBooks = books.FindAll(b => b.Price < 10);
foreach (var book in cheapBooks)
{
Console.WriteLine(book.Title);
}
}
static void LambdaExpressions()
{
var lambdaExamples = new LambdaExamples();
var books = new LambdaExpressions.Book();
var bookRepository = new LambdaExpressions.BookRepository().GetBooks();
var cheapBooks = bookRepository.FindAll(books.IsCheaperThanTenDollars);
foreach (var book in cheapBooks)
{
Console.WriteLine(book.Title);
}
// This Lambda Expression is exactly the same as the above code
var cheapBooksLambda = bookRepository.FindAll(book => book.Price < 10);
foreach (var book in cheapBooksLambda)
{
Console.WriteLine(book.Title);
}
}
static void Main(string[] args)
{
//anonymous method
//no access modifer
//no name
//no return statement.
//why use anonymous method? for convenience
//example:
//takes a number and returns a square of that number...
//typically you would do this (see square method)
Console.WriteLine(Square(5));
//lambda example
//syntax
//args => expression
//args goes to expression
//number => number * number;
//to get the 'return' action we have to assign it to a delegate
//we use func because we want to return a value
//in the func the first argument is the argument type for the method and 2nd is the datastype for the return value
Func<int, int> square = number => number * number;
//calling the delegate here
Console.WriteLine(square(9));
//if you don't need any arguments you write a lambda expression like this:
//() => ...
//1 argument
// x => ...
//multiple args
//(x,y,z) => ...
//scope - lambda has access to variables passed and anythign defined in the function the lambda was created in.
const int factor = 5;
Func<int, int> multiplier = n => n * factor;
Console.WriteLine(multiplier(6));
//more practical and common usecase of lambda expression
//write code to return all books that are less than 10 dollars
//traditional way
var books = new BookRepository().GetBooks();
//the findall function gets a predicate method passed
//predicate is a deleagate pointing to a function.
//this basically iterates through the method and return it if the condition is sastisfied in the results.
var cheapBooks = books.FindAll(IsCheaperThan10Dollars);
foreach (var book in cheapBooks)
{
Console.WriteLine(book.Title);
}
//now let's the above with a lambda
//the problem is everytime you want to call find you have to go create a method etc.
//with a lamdba you can do this:
var cheapBooks2 = books.FindAll(book => book.Price < 10);
//in c# it's pretty common to just use a single letter with the lamdba arguments.
//in the exmaple above we are working with books you could change the line above to
//var cheapBooks2 = books.FindAll(b => b.Price < 10);
Func <int, int> DoAdd = addme => addme + 5;
Console.WriteLine(DoAdd(5));
}