func with lambda expression c# code example

Example 1: c# lambdas

//Lambdas are just short handed anonymous method or functions usally 
//for use in passing to other methods or functions to call such as a sort.
//Example:
//The Lambda used here after the =s
Action ExampleContainerForDelagate = ()=>
	{/*Do something such as this example*/
    	Console.WriteLine("Hello world");
	};
//has been shorted from this anonymous delegate or method.
Action ExampleContainerForDelagate = delegate () { Console.WriteLine("Hello world"); };
//And this full (named) method signature method passing
Action ExampleContainerForDelagate = ExampleMethod;
void ExampleMethod()
{ Console.WriteLine("Hello world"); }
//usage example
List<int> ExampleList = new List(){1,3,0};
ExampleList.Sort((x,y)=>{return x - y; });
//The Sort will sort based on the return values from the Lambda passed.
//a negative will be seen as a smaller than the next number
//a 0 will be seen as equal
//and a positive will be seen as bigger than the next number
//by switching x and y postion in the 'return x - y;' you will effectively 
//change the sort to descending order. This is there for useful for sorting 
//based on needs or where it is not obvious how to sort.

Example 2: c# func

using System;
using System.Collections.Generic;
using static System.Console;
namespace CSFlow.Delegates.Others
{
    public class ActionFunc
    {

        public static void Run ()
        {
            // Example of : Action
            // Use action when a mathod return void
            Action<string> display = new Action<string>(DisplayMessage);
            display("Calculate Discount :");

            // Example of : Func
            // Use action when a mathod return value
            Func<double, double> discount = new Func<double, double>(Discount);
            display(discount(12.5).ToString());

            List<Customer> custList = new List<Customer>();
            custList.Add(new Customer { Id = 1, FirstName = "Joydip", LastName = "Kanjilal", State = "Telengana", City = "Hyderabad", Address = "Begumpet", Country = "India" });
            custList.Add(new Customer { Id = 2, FirstName = "Steve", LastName = "Jones", State = "OA", City = "New York", Address = "Lake Avenue", Country = "US" });
            custList.Add(new Customer { Id = 3, FirstName = "Sefat", LastName = "Anam", State = "OSA", City = "New York", Address = "Manhatten", Country = "US" });

            // Example of : Predicate
            // Use Predicate for search data
            Predicate<Customer> FindAddress = customer => customer.Address == "Manhatten";

            Customer searchData = custList.Find(FindAddress);

            display($"{searchData?.FirstName} {searchData?.LastName} From - {searchData?.City} ");

            ReadKey();
        }

        static void DisplayMessage (string message)
        {
            WriteLine(message);
        }

        static double Discount (double money)
        {
            return money * .5;
        }

        class Customer
        {
            public int Id { get; set; }
            public string FirstName { get; set; }
            public string LastName { get; set; }
            public string Address { get; set; }
            public string City { get; set; }
            public string State { get; set; }
            public string Country { get; set; }
        }
    }
}