c# list 去重复

素颜马尾好姑娘i 2022-08-23 03:57 220阅读 0赞

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);
                }
            }
        }
    }

输出结果 ：0  3   4