valueandreferencetypesValuetypevariablescanbeassignedavaluedirectly.TheyarederivedfromtheclassSystem.ValueType.Thevaluetypesdirectlycontaindata.Referencetypesrefertomemorylocations.areferencetypedoesn'tstoreitsvaluedirectly.Instead,itstorestheaddresswherethevalueisbeingstored.Inotherwords,areferencetypecontainsapointertoanothermemorylocationthatholdsthedata.ref&outTheobjectTypepublicclassStack{intposition;object[]data=newobject[10];publicvoidPush(objecto){data[position++]=o;}publicobjectPop(){returndata[--position];}}Stackstack=newStack();stack.Push("sausage");strings=(string)stack.Pop();//DowncastConsole.WriteLine(s);Boxing(裝箱)andUnboxing(拆箱)Boxingistheactofcastingavalue-typeinstancetoareferencetypeinstance.intx=9;objectobj=x;//BoxtheintUnboxingreversestheboxingoperation,bycastingtheobjectbacktotheoriginalvaluetype。inty=(int)obj;//Unboxtheinttypematchesinunboxingobjectobj=9;//9isinferredtobeoftypeintlongx=(long)obj;//InvalidCastExceptionMembersofObject

publicexternTypeGetType();publicvirtualboolEquals(objectobj);publicstaticboolEquals(objectobjA,objectobjB);publicstaticboolReferenceEquals(objectobjA,objectobjB);publicvirtualintGetHashCode();publicvirtualstringToString();protectedoverridevoidFinalize();protectedexternobjectMemberwiseClone();TheGetTypeMethodandtypeofOperatortwobasicwaystogetaSystem.Typeobject:GetTypeontheinstance(GetTypeisevaluatedatruntime)typeofoperatoronatypename(typeofisevaluatedstaticallyatcompiletime).exampleintx=3;Console.Write(x.GetType().Name);//Int32Console.Write(typeof(int).Name);//Int32Console.Write(x.GetType().FullName);//System.Int32Console.Write(x.GetType()==typeof(int));//TrueEqualsobjectx=3;objecty=3;Console.WriteLine(x==y);//FalseConsole.WriteLine(x.Equals(y));//TrueReferenceEqualsTODOGetHashCodeTODOTheToStringMethodTheToStringmethodreturnsthedefaulttextualrepresentationofatypeinstance.strings1=1.ToString();//s1is"1"strings2=true.ToString();//s2is"True"Problem2Definegeometric