publicclassPerson{publicstringpersonName;//定义年龄为可空类型,这样就可以赋予其null值publicint?personAge;//下面前三个构造函数都是去调用参数最多的第四个构造函数,只取它们所需要的部分参数即可//这样的做法就是this串联构造函数publicPerson():this(,0){}publicPerson(stringname):this(evan,null){}publicPerson(intage):this(,20){}publicPerson(stringname,int?age){this.personName=name;//通过??判断传入的age是否null值//如果属于null值,则赋值100this.personAge=age??100;}publicvoidDisplay(){Console.WriteLine(Name:{0},Age:{1}\n,personName,personAge);}}publicclassPerson{publicstringpersonName;//定义年龄为可空类型,这样就可以赋予其null值publicint?personAge;//下面前三个构造函数都是去调用参数最多的第四个构造函数,只取它们所需要的部分参数即可//这样的做法就是this串联构造函数publicPerson():this(,0){}publicPerson(stringname):this(evan,null){}publicPerson(intage):this(,20){}publicPerson(stringname,int?age){this.personName=name;//通过??判断传入的age是否null值//如果属于null值,则赋值100this.personAge=age??100;}publicvoidDisplay(){Console.WriteLine(Name:{0},Age:{1}\n,personName,personAge);}}