LINQ Example

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace skit_d_inaction
{
    class Program
    {
        static void WriteCollection(Object[] collection)
        {
            foreach (var t in collection)
            {
                Console.WriteLine(t);
            }

            Console.WriteLine(Environment.NewLine);
        }

        static void Main(string[] args)
        {
            var products = Product.GetSamples();
            var suppliers = Supplier.GetSamples();

            var filtered0 = from p in products
                           join s in suppliers
                             on p.SupplierID equals s.ID
                           select new { SupplierName = s.Name, ProductName = p.Name };

            var filtered1 = from p in products
                            join s in suppliers
                              on p.SupplierID equals s.ID
                            where p.Price > 1000
                            orderby p.Name, s.Name
                            select new { SupplierName = s.Name, ProductName = p.Name };

            WriteCollection(filtered0.ToArray());
            WriteCollection(filtered1.ToArray());
        }
    }

    class Supplier
    {
        public string Name { get; set; }
        public uint ID { get; set; }

        public static Supplier[] GetSamples()
        {
            return new Supplier[]
            {
                new Supplier() { ID = 0, Name = "Apple" },
                new Supplier() { ID = 1, Name = "Samsung" },
                new Supplier() { ID = 2, Name = "Microsoft" },
                new Supplier() { ID = 3, Name = "Matarola inc" }
            };
        }
    }

    class Product
    {
        public string  Name   { get; set; }
        public decimal Price  { get; set; }
        public uint SupplierID { get; set; }

        public Product(string name, string price, uint supplierID)
        {
            Name = name;
            Price = decimal.Parse(price);
        }

        public Product() { }

        public override string ToString()
        {
            return $"{Name}: {Price}";
        }

        public static Product[] GetSamples()
        {
            return new Product[]
            {
                new Product() { Name = "Product #1", Price = 1000, SupplierID = 0 },
                new Product() { Name = "Product #2", Price = 2000, SupplierID = 0 },
                new Product() { Name = "Product #3", Price = 3000, SupplierID = 1 },
                new Product() { Name = "Product #4", Price = 4000, SupplierID = 2 },
                new Product() { Name = "Product #5", Price = 5000, SupplierID = 3 }
            };
        }
    }
}