using System;
using System.Collections.Generic;
using System.Linq;namespace LinqTest
{class Program{static void Main(){List<Product> listProduct = new List<Product> {new Product{StockNum=1,ProductNo="01",Tag="a"},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"},};//注:处理目标->将"编号(ProductNo)"相同的产品记录，"库存量(StockNum)"合并，"附属标签(Tag)"合并//合并处理listProduct.ForEach(c => {var group = listProduct.Where(a => a.ProductNo == c.ProductNo);c.StockNum = group.Sum(x => x.StockNum);c.Tag = group.Select(t => t.Tag).ToList().Join();});//去重复listProduct = listProduct.Distinct(new ProductNoComparer()).ToList();//输出验证listProduct.ForEach(c =>{Console.WriteLine("ProductNo={0},StockNum={1},Tag={2}", c.ProductNo, c.StockNum, c.Tag);});  //输出结果://ProductNo=01,StockNum=3,Tag=a,b//ProductNo=02,StockNum=7,Tag=c,d//ProductNo=03,StockNum=5,Tag=eConsole.Read();}}/// <summary>/// 工具类(一般开发中，可定义在自己的工具类库里)/// </summary>static class Utils {/// <summary>/// List扩展方法，将List元素用分隔符连接后，返回字符串/// </summary>/// <typeparam name="T"></typeparam>/// <param name="list"></param>/// <param name="splitStr"></param>/// <returns></returns>public static String Join<T>(this List<T> list, string splitStr=","){string result = string.Empty;foreach (var item in list){result += item.ToString() + splitStr;}return result.Trim(splitStr.ToCharArray());}}/// <summary>/// 产品实体类/// </summary>class Product{/// <summary>/// 库存/// </summary>public int StockNum { set; get; }/// <summary>/// 产品编号/// </summary>public String ProductNo { set; get; }/// <summary>/// 附属标签/// </summary>public String Tag { set; get; }}/// <summary>/// 去"重复"时候的比较器(只要ProductNo相同，即认为是相同记录)/// </summary>class ProductNoComparer : IEqualityComparer<Product>{public bool Equals(Product p1, Product p2){if (p1 == null)return p2 == null;return p1.ProductNo == p2.ProductNo;}public int GetHashCode(Product p){if (p == null)return 0;return p.ProductNo.GetHashCode();}}
}