safaribook-pro-aspnet-mvc3/chap5_essential_language_features/essential_csharp_features/Program.cs

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using automatically_implemented_properties;

namespace automatically_implemented_properties
{
    class Program
    {
        static void Main(string[] args)
        {
            Product[] products =
            {
                new Product {Name = "Kayak", Category = "Watersports", Price = 275M},
                new Product {Name = "Lifejacket", Category = "Watersports", Price = 48.95M},
                new Product {Name = "Soccer ball", Category = "Soccer", Price = 19.50M},
                new Product {Name = "Corner flag", Category = "Soccer", Price = 34.95M}
            };

            // define the array to hold results
            Product[] results = new Product[3];
            // sort the contents of the array
            Array.Sort(products, (item1, item2) =>
            {
                return Comparer<decimal>.Default.Compare(item1.Price, item2.Price);
            });
            // get the first three items in the array as the results
            Array.Copy(products, results, 3);
            // print out the name
            foreach (Product p in results)
            {
                Console.WriteLine("Item: {0}, Cost: {1}", p.Name, p.Price);
            }

            int count = 0;
            // print the name
        }

    }

    public static class MyExtensionMethod
    {
        public static decimal TotalPrices(this IEnumerable<Product> productEnum)
        {
            decimal total = 0;
            foreach (Product prod in productEnum)
            {
                total += prod.Price;
            }
            return total;
        }

        public static IEnumerable<Product> FilterByCategory(this IEnumerable<Product> productEnum,
                                                            string categoryParam)
        {
            foreach (Product prod in productEnum)
            {
                if (prod.Category == categoryParam)
                {
                    yield return prod;
                }
            }
        }

        public static IEnumerable<Product> Filter(this IEnumerable<Product> productEnum,
            Func<Product, bool> selectorParam)
        {
            foreach (Product prod in productEnum)
            {
                if (selectorParam(prod))
                {
                    yield return prod;
                }
            }
        }
    }
}