using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Text.RegularExpressions;using System.IO;using System.Collections;using Data = System.Data.SqlClient;namespace COL_TEST{    class Program    {        static void Main(string[] args)        {            //一个对象的 GetHashCode 方法必须总是返回同一个哈希代码            //Console.WriteLine(ht.GetHashCode());            //Console.WriteLine(ht.GetHashCode());            A a = new A(2, 2);            A aa = new A(1, 4);            A bb = new A(1, 3);            Dictionary
    
      hs = new Dictionary
     
      ();            hs.Add(a, 2);            hs.Add(aa, 2);            hs.Add(bb, 2);            foreach (KeyValuePair
      
        p in hs)            {                Console.WriteLine("Key: " + p.Key + "   Value: " + p.Value);                Console.WriteLine("hashCode:{0}", p.Key.GetHashCode());            }            Console.WriteLine("-----------------");            /***************/            Hashtable hht = new Hashtable();            Class3 cc = new Class3(2, 3);            Class3 cc2 = new Class3(1, 4);            Class3 cc3 = new Class3(3, 3);            hht.Add(cc, "test1");            hht.Add(cc2, "test2");            hht.Add(cc3, "test3");            //cc.x = 5;  //如果修改cc的状态,会导致cc遍历不到            foreach (var item in hht.Keys)            {                Console.WriteLine(item.ToString());                Console.WriteLine(hht[item]);            }            Console.Read();             //如果将一个引用类型的数据加入到hashTable中,首先会调用该类型的GetHashCode方法,返回的键值为重写toString 方法返回值            //        }    }    public struct MyStruct    {        public int _sx;        public string _msg;        public int _id;        public DateTime _epoch;    }    class A    {        int i, j;        public A(int i, int j)        {            this.i = i;            this.j = j;        }        public override Int32 GetHashCode()        {            return i * j;        }        public override string ToString()        {            return String.Format("({0},{1})", i, j);        }    }    class Class3    {        public int x;        int y;        public Class3(int x, int y)        {            this.x = x;            this.y = y;        }        public override int GetHashCode()        {            Console.WriteLine("判断hashcode");            return x + y;        }        public override bool Equals(object obj)        {            Console.WriteLine("判断equals");            return base.Equals(obj);        }        public override string ToString()        {            return x.ToString() + y.ToString();        }    }  }