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

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

namespace automatically_implemented_properties
{
    class Program
    {
        static void Main(string[] args)
        {
            // create and populate Shopping Cart, implementing IEnumerable<Product> interface
            ShoppingCart products = new ShoppingCart
            {
                Products = new List<Product>
                {
                    new Product {Name = "Kayak", Price = 275M},
                    new Product {Name = "Lifejacket", Price = 48.95M},
                    new Product {Name = "Soccer ball", Price = 19.50M},
                    new Product {Name = "Corner flag", Price = 34.95M}
                }
            };
            
            // create and populate an array of Product objects, implementing IEnumerable<Product> interface
            Product[] productArray =
            {
                new Product {Name = "Kayak", Price = 275M},
                new Product {Name = "Lifejacket", Price = 48.95M},
                new Product {Name = "Soccer ball", Price = 19.50M},
                new Product {Name = "Corner flag", Price = 34.95M}
            };
            
            // get total value of the products in cart
            decimal cartTotal = products.TotalPrices();
            decimal arrayTotal = productArray.TotalPrices();
            
            Console.WriteLine("Total: {0:c}", cartTotal);
            Console.WriteLine("Array Total: {0:c}", arrayTotal);
        }

    }

    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;
        }
    }
}