Public, Private and Protected "keywards/ access modifiers" are used similarly as they are with variables. Protected variables, methods or class CAN ONLY be used by an inherited class.
There is no such thing as visibility mode in C++. Visibility is a function of information hiding but that relates to the way in which implementation details can be obfuscated within binary executables and libraries where only the interface need be exposed in a plain-text header file. This has nothing whatsoever to do with object oriented programming since information hiding is also possible in C. You probably meant access specifiers. There are three levels: private, protected and public. Private access limits access to the class and to friends of the class. Protected is the same as private but extends access to derivatives of the class. Public access imposes no limits. In terms of inheritance, the specified access level determines the accessibility of the protected and public members of the base class (private members are never inherited and will always remain private to the base class). in essence, members with access greater than the specified inheritance are reduced to the specified access. Thus if you specify protected inheritance, all public members of the base class become protected members of the derivative, while private inheritance reduces all public and protected members to private access. You may also reduce access to specific base class members simply be redeclaring them with the appropriate access.
When you derive a class (the sub-class) from a base class using protected access, all public members of the base class become protected members of the derived class, while protected members of the base class will remain protected. Private members are never inherited so they remain private to the base class. By contrast, if you use public inheritance, the public members of the base class remain public to the derived class, while protected members of the base class remain protected in the derived class. If you use private inheritance, both the public and protected members of the base class become private to the derived class. Note that accessibility cannot be increased, only reduced or left the same. That is, a protected member of a base class cannot be inherited as a public member of a derived class -- it can only be declared private or remain protected. Note also that accessibility is viewed from outside of the derived class. That is, all members of a base class other than the private members are inherited by the derived class and are therefore fully accessible to the derived class. But from outside of the derived class, all base class accessibility is determined by the access specified by the type of inheritance.
single level inheritance eg ( class B extends Class A) Multilevel inheritance eg( class C extends class B and class B extends class A) multiple inheritance Class C inherits Class A features as well as Class B featues.This type of inheritance is not allowed in JAVA.
Multi-level inheritance involves at least 3 classes, a, b and c, such that a is derived from b, and b is derived from c. c is therefore the least-derived base class, b is an intermediate base class and a is the most-derived class.
struct employee { }; struct supervisor : employee { // single inheritance -- a supervisor inherits all the public and protected properties of an employee. }; struct manager : supervisor { // multilevel inheritance -- a manager inherits all the public and protected properties of a supervisor (and therefore an employee). };
Public derivation or public inheritance means that all the public members of the base calls are declared public in the derived class while the protected members remain protected. Protected inheritance means all the public members of the base class are declared protected in the derived class, as are the protected members. Private inheritance means all the public and protected members of the base class are declared private in the derived class. Private members of the base class are never inherited and are therefore unaffected by inheritance. Note that regardless of the type of inheritance specified, individual non-private members of the base class can be inherited with public or protected access as required of the derived class. The type of inheritance can be therefore be thought of as being the default inheritance for all base class members which can (optionally) be overridden for specific members where required.
By visibility I assume you mean member accessibility. C++ uses three levels of accessibility: private, protected and public. Private members are only accessible to the class itself and friends of the class. Protected members are the same as private members except derived classes also have access. Public members are fully accessible. With regards inheritance, base class members with greater access than that specified are reduced to the specified access in the derived class. Thus public inheritance has no effect on base class member access. Protected inheritance reduces public members of the base class to protected members of the derived class. Private inheritance reduces both public and protected members of the base class to private members of the derived class. Private members of the base class are never inherited, thus they always remain private to the base class. Note that access to base class members can never be increased through inheritance, only reduced or kept the same. However, as well as defining an overall inheritance access, you can also specify member-wise inheritance access. Thus you could use public inheritance overall, but specify certain public members of the base class to be protected or private in the derived class and/or certain protected members of the base class to be private members of the derived class.
There is no such thing as visibility mode in C++. Visibility is a function of information hiding but that relates to the way in which implementation details can be obfuscated within binary executables and libraries where only the interface need be exposed in a plain-text header file. This has nothing whatsoever to do with object oriented programming since information hiding is also possible in C. You probably meant access specifiers. There are three levels: private, protected and public. Private access limits access to the class and to friends of the class. Protected is the same as private but extends access to derivatives of the class. Public access imposes no limits. In terms of inheritance, the specified access level determines the accessibility of the protected and public members of the base class (private members are never inherited and will always remain private to the base class). in essence, members with access greater than the specified inheritance are reduced to the specified access. Thus if you specify protected inheritance, all public members of the base class become protected members of the derivative, while private inheritance reduces all public and protected members to private access. You may also reduce access to specific base class members simply be redeclaring them with the appropriate access.
When you derive a class (the sub-class) from a base class using protected access, all public members of the base class become protected members of the derived class, while protected members of the base class will remain protected. Private members are never inherited so they remain private to the base class. By contrast, if you use public inheritance, the public members of the base class remain public to the derived class, while protected members of the base class remain protected in the derived class. If you use private inheritance, both the public and protected members of the base class become private to the derived class. Note that accessibility cannot be increased, only reduced or left the same. That is, a protected member of a base class cannot be inherited as a public member of a derived class -- it can only be declared private or remain protected. Note also that accessibility is viewed from outside of the derived class. That is, all members of a base class other than the private members are inherited by the derived class and are therefore fully accessible to the derived class. But from outside of the derived class, all base class accessibility is determined by the access specified by the type of inheritance.
it is nomrmal
Public, protected and private inheritance determine how the public and protected base class members are inherited by the derived class. Private members are never inherited and are therefore unaffected by the type of inheritance (they remain private to the base class). The following table summarises how inheritance affects accessibility of base class members with respect to the derived class: public inheritanceprotected inheritanceprivate inheritancepublic member of base classpublic member of derived classprotected member of derived classprivate member of derived classprotected member of base classprotected member of derived classprotected member of derived classprivate member of derived classprivate member of base classprivate member of base classprivate member of base classprivate member of base class Note that accessibility to individual public and protected base class members can be overridden within the derived class, regardless of the type of inheritance specified.
Single-inheritance is where one class inherits directly from another class: class A {}; class B : public A {}; Here, class B inherits all the public and protected members of class A. Multiple-inheritance is where one class inherits directly from two or more classes: class A {}; class B {}; class C : public A, public B {}; Here, class C inherits all the public and protected members of both A and B. Multi-level inheritance is where one class inherits from another class that itself derived. class A {}; class B : public A {}; class C : public B {}; Here, class B inherits all the public and protected members of A while class C inherits all the public and protected members of B, including those inherited from A. Virtual inheritance applies to multi-level inheritance whereby a virtual base class becomes a direct ancestor to the most-derived class. This variation of inheritance is typically used in multiple inheritance situations where two or more intermediate classes inherit from the same base class: class A {}; class B : public virtual A {}; class C : public virtual A {}; class D : public B, public C {}; Here, classes B and C both inherit from class A. Without virtual inheritance this would mean class D would inherit two instances of A (B::A and C::A), thus creating ambiguity when referring to D::A. By employing virtual inheritance, D inherits directly from A, and both B and C inherit from D::A. In other words, B and C share the same instance of A. Another use of virtual inheritance is when you need to make a class final. class A; class B { friend class A; B() {} // private constructor }; class A : public virtual B { }; Here, class A is the final class. Class B is a helper class that has a private constructor while class A is declared a friend of class B. Class A is therefore the only class that can inherit from class B as it is the only class that can construct objects from class B. However, by inheriting class B virtually, we ensure that no other class can be derived from class A because virtual inheritance ensures that the most-derived class must be able to construct a class B object first. Currently, only class A has that privilege and must always be the most-derived class.
single level inheritance eg ( class B extends Class A) Multilevel inheritance eg( class C extends class B and class B extends class A) multiple inheritance Class C inherits Class A features as well as Class B featues.This type of inheritance is not allowed in JAVA.
Multi-level inheritance involves at least 3 classes, a, b and c, such that a is derived from b, and b is derived from c. c is therefore the least-derived base class, b is an intermediate base class and a is the most-derived class.
struct employee { }; struct supervisor : employee { // single inheritance -- a supervisor inherits all the public and protected properties of an employee. }; struct manager : supervisor { // multilevel inheritance -- a manager inherits all the public and protected properties of a supervisor (and therefore an employee). };
Unit Inheritance or Single Inheritance refers to the situation where one class inherits/extends the features of another class ex: public class A extends B { ..... } The above is an example of unit inheritance.
Multiple inheritance occurs when a class is derived directly from two or more base classes. class b1 {}; class b2 {}; class d: public b1, public b2 {}; // multiple inheritance class