2019-COMPOSITEOBJECTRUNTIMEPOLYMORPHISM：复合对象的运行时多态性-文档资料

1、Prepared byN.Sathish KumarCSE/ LecturerSKRECCOMPOSITE OBJECT RUNTIMEPOLYMORPHISM Inhentance results m a "composite obj ect at run-time. Public methods are combined into one set of public methods, but with distinct names qualified by the class name in which they are defined Data layout is combin

2、ed as well, with compile-time access control (e.g., private) still applies:Object Da1iiLutBase panDerived partObjed Mettad LiyoinBa-SE：:Basej 弧e:aB葩&JDenmLDemdQDemDerrijedfiiid With inheritance, private data in the base class is still private C+ introduces the "protected clause” for allowin

3、g a derived class to have special access privileges to the base class. Protected data and methods are only visible to base classes. Use protected data and methods to selectively break encapsulation so that the subclass can access the data and/or methods. NOTE: when you construct a composite object,

4、the base class constructor is executed before the derived class constructor. That is objects are constructed from the base down the inheritance hierarchy. Usually, destruction is the reversea derived class destructor is executed before a base class destructor. Inheritance Example When a derived clas

5、s is constructed, the base class constructor is executed prior to the derived class constructor. Thus the derived class can pass arguments to the base class constructor using the initialize list.include<iostream.h>#include<conio.h>class Baseprivate:int x;public:Base() : x(0) cout«11

6、 nnnDefault BaseBase(int x) : x(x)cout«Hnnnparameter Base x=H«x Base()cout«nnnnDestructor is called11;class Derived : public Baseprivate:int y;char *s;public:Derived(): Base(), y(O)，s(NULL) cout«11 nnnDefault derived class called y= n«y;Derived(int x, int y): Base(x), y(0), s(NULL)cout«HnnnDerived parameter is called x=n«x«n,y=M«y;Derived。cout«1 fnnnDerived destructor is called11;void main() clrscr();Base a;Base b(l