using System;using System.Collections.Generic;using System.Linq;namespace LinqTest{    class Program    {        static void Main()        {            List
     
       listProduct = new List
      
        {                    new Product{StockNum=1,ProductNo="01",Tag="a"},                    new Product{StockNum=1,ProductNo="01",Tag="a"},                    new Product{StockNum=1,ProductNo="01",Tag="a"},                    new Product{StockNum=2,ProductNo="01",Tag="b"},                    new Product{StockNum=2,ProductNo="01",Tag="b"},                    new Product{StockNum=2,ProductNo="01",Tag="b"},                    new Product{StockNum=3,ProductNo="02",Tag="c"},                    new Product{StockNum=4,ProductNo="02",Tag="d"},                    new Product{StockNum=5,ProductNo="03",Tag="e"},                };            //去重复            var listProduct1 = listProduct.Select(s => new            Product            {                StockNum = s.StockNum,                ProductNo = s.ProductNo,                Tag = s.Tag            }).Distinct(new ProductNoComparer()).ToList();            //输出验证            listProduct1.ForEach(c =>            {                Console.WriteLine("ProductNo={0},StockNum={1},Tag={2}", c.ProductNo, c.StockNum, c.Tag);            });            Console.WriteLine("-------------------");            //去重复            var listProduct2 = listProduct.Select(s => new            {                s.ProductNo,                s.StockNum,                s.Tag            }).Distinct().ToList();            //输出验证            listProduct2.ForEach(c =>            {                Console.WriteLine("ProductNo={0},StockNum={1},Tag={2}", c.ProductNo, c.StockNum, c.Tag);            });            Console.Read();        }    }    /// 
       
    /// 产品实体类    /// 
    class Product    {        /// 
       
        /// 库存        /// 
        public int StockNum { set; get; }        /// 
       
        /// 产品编号        /// 
        public String ProductNo { set; get; }        /// 
       
        /// 附属标签        /// 
        public String Tag { set; get; }    }    /// 
       
    /// 去"重复"时候的比较器(只要ProductNo相同，即认为是相同记录)    /// 
    class ProductNoComparer : IEqualityComparer
       
            {        public bool Equals(Product p1, Product p2)        {            if (p1 == null)                return p2 == null;            return p1.ProductNo == p2.ProductNo && p1.StockNum == p2.StockNum && p1.Tag == p2.Tag;        }        public int GetHashCode(Product p)        {            if (p == null)                return 0;            return p.ProductNo.GetHashCode();        }    }}