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("") { aa = , bb = "", cc = true, dd = "" };

            test b = new test("") { aa = , bb = "", cc = true, dd = "" };

            Console.WriteLine(a.Equals(b));

            ReadLine();

        }

    }

test b = new test("") { aa = , bb = "", cc = true, dd = "" };

等效于

test b = new test("");

b.aa = ; b.bb = ""; b.cc = true; b.dd = "";