c# list 去重复

针对数组可以用List.Distinct(),可以过滤掉重复的内容。
针对对象中的某个字段只能用Distinct(IEqualityComparer<T>)

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

namespace listSort
{
    public class StrItem
    {
        public int id;
        public int num;
    }

    public class Comparint : IEqualityComparer<StrItem>
    {

        public bool Equals(StrItem x, StrItem y)
        {
            if (x == null && y == null)
                return false;
            return x.num == y.num;
        }

        public int GetHashCode(StrItem obj)
        {
            return obj.ToString().GetHashCode();
        }
    }


    class Program
    {
        static void Main(string[] args)
        {
            delegateSort();
            Console.ReadLine();
        }

        

        static int sort(StrItem str1,StrItem str2)
        {
            int ret = 0;
            if (str1.id > str2.id) //id从小到大
            {
                return 1;
            }
            else if (str1.id == str2.id)
            {
                if (str1.num < str2.num)//num从大到小
                {
                    return 1;
                }
            }
            return ret;
        }

        static void delegateSort()
        {
            List<StrItem> listItem = new List<StrItem>();
            StrItem str1 = new StrItem();
            str1.id = 1;
            str1.num = 0;
            listItem.Add(str1);

            StrItem str2 = new StrItem();
            str2.id = 2;
            str2.num = 3;
            listItem.Add(str2);

            StrItem str3 = new StrItem();
            str3.id = 2;
            str3.num = 4;
            listItem.Add(str3);

            StrItem str4 = new StrItem();
            str4.id = 3;
            str4.num = 3;
            listItem.Add(str4);

            listItem.Sort(sort);

            listItem = listItem.Distinct(new Comparint()).ToList();

            foreach (var item in listItem)
            {
                Console.WriteLine(item.num);
            }
        }
    }
}