问在.NET 4中将C＃对象转换为JSON字符串？

class MyDate

{

    int year, month, day;

}

class Lad

{

    string firstName;

    string lastName;

    MyDate dateOfBirth;

}

{

    ""firstName"":""Markoff"",

    ""lastName"":""Chaney"",

    ""dateOfBirth"":

    {

        ""year"":""1901"",

        ""month"":""4"",

        ""day"":""30""

    }

}