class test:IEquatable<test>    {        public int aa { get; set; }        public string bb { get; set; }        public bool cc { get; set; }        public string dd;        public test(string dd) {            this.dd = dd;        }        public bool Equals(test other)        {            return (this.aa == other.aa && this.bb == other.bb && this.cc == other.cc && this.dd == other.dd);        }    }    class Program    {        static void Main(string[] args)        {            test a = new test("22") { aa = 1, bb = "11", cc = true, dd = "22" };            test b = new test("22") { aa = 1, bb = "11", cc = true, dd = "224" };            Console.WriteLine(a.Equals(b));            ReadLine();        }    }

test b = new test("22") { aa = 1, bb = "11", cc = true, dd = "224" };等效于test b = new test("22");b.aa = 1; b.bb = "11"; b.cc = true; b.dd = "224";