C# 集合的交集 差集 并集 去重

两个对象list，直接比较是不行的，因为他们存的地址不一样

需要重写GetHashCode()与Equals(object obj)方法告诉电脑

class Student    {        public int Id { get; set; }        public string Name { get; set; }        public int Age { get; set; }    }    class CompareStudent : IEqualityComparer
     
          {        public bool Equals(Student x, Student y)        {            return x.Id == y.Id;        }        public int GetHashCode(Student p)        {            if (p == null)                return 0;            return p.Id.GetHashCode();        }    }    class Program    {        static void Main(string[] args)        {            List
      
        stuA = new List
       
        ();            List
        
          stuB = new List
         
          ();            stuA.Add(new Student { Id = 1, Name = "1", Age = 1 });            stuA.Add(new Student { Id = 5, Name = "5", Age = 2 });            stuB.Add(new Student { Id = 1, Name = "1", Age = 1 });            stuB.Add(new Student { Id = 2, Name = "2", Age = 2 });            stuB.Add(new Student { Id = 3, Name = "3", Age = 3 });            stuB.Add(new Student { Id = 4, Name = "4", Age = 4 });            var result = stuA.Where(a => !stuB.Exists(b => b.Id == a.Id)); //在A中存在不再B中存在 即求差集            var resc = stuA.Except(stuB, new CompareStudent()); //差集            var resj = stuA.Intersect(stuB, new CompareStudent());// 交集            var resb = stuA.Union(stuB, new CompareStudent()); //并集            var resD = stuB.Distinct(new CompareStudent()); //去重        }    }