《C++教程英文版》PPT课件.ppt

《《C++教程英文版》PPT课件.ppt》由会员上传分享，免费在线阅读，更多相关内容在教育资源-天天文库。

1、110Classes:A DeeperLook,Part2210.1IntroductionconstobjectsandconstmemberfunctionsPreventmodificationsofobjectsEnforcetheprincipleofleastprivilegeCompositionClasseshavingobjectsofotherclassesasmembersFriendshipEnablesclassdesignertospecifythatcertainnon-memberfunctionscanaccessthecl

2、ass’snon-publicmembers310.1Introduction(Cont.)thispointerDynamicmemorymanagementnewanddeleteoperatorsstaticclassmembersProxyclassesHideimplementationdetailsofaclassfromclientsPointer-basestringsUsedinClegacycodefromthelasttwodecades410.2const(Constant)ObjectsandconstMemberFunctions

3、PrincipleofleastprivilegeOneofthemostfundamentalprinciplesofgoodsoftwareengineeringAppliestoobjects,tooconstobjectsKeywordconstSpecifiesthatanobjectisnotmodifiableAttemptstomodifytheobjectwillresultincompilationerrors510.2const(Constant)ObjectsandconstMemberFunctions(Cont.)constmem

4、berfunctionsOnlyconstmemberfunctioncanbecalledforconstobjectsMemberfunctionsdeclaredconstarenotallowedtomodifytheobjectAfunctionisspecifiedasconstbothinitsprototypeandinitsdefinitionconstdeclarationsarenotallowedforconstructorsanddestructors6SoftwareEngineeringObservation10.2Aconst

5、memberfunctioncanbeoverloadedwithanon-constversion.Thecompilerchooseswhichoverloadedmemberfunctiontousebasedontheobjectonwhichthefunctionisinvoked.Iftheobjectisconst,thecompilerusestheconstversion.Iftheobjectisnotconst,thecompilerusesthenon-constversion.7CommonProgrammingError10.4A

6、ttemptingtodeclareaconstructorordestructorconstisacompilationerror.8OutlineTime.h(1of2)constkeywordtoindicatethatmemberfunctioncannotmodifytheobject9OutlineTime.h(2of2)10OutlineTime.cpp(1of3)11OutlineTime.cpp(2of3)constkeywordinfunctiondefinition,aswellasinfunctionprototype12Outlin

7、eTime.cpp(3of3)13Outlinefig10_03.cpp(1of2)Cannotinvokenon-constmemberfunctionsonaconstobject14Outlinefig10_03.cpp(2of2)1510.2const(Constant)ObjectsandconstMemberFunctions(Cont.)MemberinitializerRequiredforinitializingconstdatamembersDatamembersthatarereferencesCanbeusedforanydatame

8、mberMemberinitializerlistA