Demo No. 3B Inheritance II </HEAD> <BODY> <H1> <CENTER><B> <FONT SIZE= 4>Inheritance</FONT></B> </CENTER></H1> <H2> <FONT SIZE= 3> Inheritance is achieved by creating new classes from exisiting ones</FONT> </H2> <P><BR> <HR> /* <BR> <PRE> 1. class "Derived" adds: (a) private data member "Derive_private_data_x" (b) public member function "DerivedGet()" 2.A base class does not know of the existence of derived classes 3. Private members of a base class remains private to the base class 4. An infinite number of classes can be inherited from a base class * <P> #include <iostream.h> class Base { private: int Base_private_data_x; public: int BaseGet() { return Base_private_data_x; } /* -----> void BaseFunction() { Base_private_data_x = DerivedGet(); } 2. A base class does not know of the existence of derived classes The actual compilation error message ----------------Configuration: Derive_3 - Win32 Debug---------------- Compiling... Derive_3.cpp D:\Cop3338_98\C++\Derived Classes\Derive3\Derive_3.cpp(16) : error C2065: 'DerivedGet' : undeclared identifier Error executing cl.exe. Derive_3.obj - 1 error(s), 0 warning(s) */ }; class Derived: public Base { private: int Derive_private_data_x; public: int DerivedGet() { return Derive_private_data_x; } /* -----> void DerivedFunction() { Base_private_data_x = BaseGet(); } 3. Private members of a base class remains private to the base class The actual compilation error message ----------------Configuration: Derive_3 - Win32 Debug---------------- Compiling... Derive_3.cpp D:\Cop3338_98\C++\Derived Classes\Derive3\Derive_3.cpp(43) : error C2248: 'Base_private_data_x' : cannot access private member declared in class 'Base' Error executing cl.exe. Derive_3.obj - 1 error(s), 0 warning(s) */ }; /* 4. An infinite number of classes can be inherited from a base class */ class Derived2: public Base { }; class derived3: public Base { }; void main() {} </PRE> <A HREF="week2.html">Go Back</A> </BODY> </HTML>