Is and as operators

The as operator has a certain range of applicability. It is only applicable to the reference type or the type that can be null, but cannot perform other conversions, such as value type conversion and custom type conversion, this type of conversion should be executed using a forced conversion expression. As returns NULL when the conversion fails. As does not throw an exception.

The is operator does not actually execute conversions. It only checks whether the specified object is compatible with the given type. To put it bluntly, it indicates whether the specified object can be converted to the given type.

Person P = new person (); p. id = 1; p. age = 23; p. name = "Zhang Fei"; object o = P; person p1 = O as person; console. writeline (p1.name); // output Zhang Fei can forcibly convert O to person type person p1 = new person (1, 20, "Zhang Fei"); person P2 = new person (2, 21, "Guan Yu"); person P3 = new person (3, 22, "Liu Bei"); List <person> personlist = new list <person> (); personlist. add (P1); personlist. add (P2); personlist. add (P3); object o = personlist; List <person> personlist1 = O as list <person>; console. writeline (personlist1 [1]. name); // output Guan Yu lecture o forced conversion list strong type set person P4 = new person (4, 24, "Zhao Yun"); object o = P4; console. writeline (P4 is person); // Output True list <person> personlist = new list <person> (); object O1 = personlist; console. writeline (O1 is person); // outputs false console. writeline (O1 is list <person>); // Output True