It'll help you for learning and gaining knowledge about Inheritance. Inheritance OOP Concept in C++.

1. PresentationPresentation
OOPOOP
Author:Author:
Asad-Ur-RehmanAsad-Ur-Rehman

2. Inheritance: ExtendingInheritance: Extending
ClassesClasses

3. IntroductionIntroduction
 Reusability is an important feature ofReusability is an important feature of
OOP.OOP.
 C++ strongly supports the conceptC++ strongly supports the concept
of reusability.of reusability.

4. IntroductionIntroduction
 The mechanism of deriving a newThe mechanism of deriving a new
class from an old one is calledclass from an old one is called
inheritance (or derivation).inheritance (or derivation).
 The old class is referred to as baseThe old class is referred to as base
class.( superclass, parent)class.( superclass, parent)
 The new class is called the derivedThe new class is called the derived
class or subclass.(child)class or subclass.(child)
continue …

5. IntroductionIntroduction
 The derived class inherits some or allThe derived class inherits some or all
of the attributes and functions fromof the attributes and functions from
the base class.the base class.
 A class can also inherit propertiesA class can also inherit properties
from more than one class or fromfrom more than one class or from
more than one level.more than one level.
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6. Single InheritanceSingle Inheritance
 A derived class with only one baseA derived class with only one base
class.class.
A
B

7. Multiple InheritanceMultiple Inheritance
 A derived class with several baseA derived class with several base
classes.classes.
A
C
B

8. Multilevel InheritanceMultilevel Inheritance
 The mechanism of deriving a classThe mechanism of deriving a class
from another derived class.from another derived class.
A
C
B

9. Derived ClassesDerived Classes
 A derived class can be defined byA derived class can be defined by
specifying its relationship with thespecifying its relationship with the
base class in addition to its ownbase class in addition to its own
details.details.
classclass derived-class-namederived-class-name :: visibility-modevisibility-mode base-class-namebase-class-name
{{
………………////
………………// members of derived class// members of derived class
………………////
};};

10. Derived ClassesDerived Classes
classclass derived-class-namederived-class-name :: visibility-modevisibility-mode base-class-namebase-class-name
{{
………………////
………………// members of derived class// members of derived class
………………////
};};
The colon indicates that the
derived-class-name is derived
from the base-class-name
The visibility mode is
optional and , if
present, may be either
private or public.
The default visibility
mode is private.
Visibility mode specifies
whether the features of
the base class are
derived privately or
publicly.
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11. Derived ClassesDerived Classes
 When a base class is privately derived by aWhen a base class is privately derived by a
derived class, “public members” of the base classderived class, “public members” of the base class
become “private members” of the derived class.become “private members” of the derived class.
 Therefore the members of the derived class canTherefore the members of the derived class can
only access the public members of the base class.only access the public members of the base class.
 They are inaccessible to the objects of theThey are inaccessible to the objects of the
derived class.derived class.
 No member of the base class is accessible to theNo member of the base class is accessible to the
objects of the derived class.objects of the derived class.
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12. Derived ClassesDerived Classes
 When a base class is publicly inherited,When a base class is publicly inherited,
”public members” of the base class”public members” of the base class
become the “public members” of thebecome the “public members” of the
derived class.derived class.
 They are accessible to the objects of theThey are accessible to the objects of the
derived class.derived class.
continue …

13. Derived ClassesDerived Classes
 The private members of the base class areThe private members of the base class are
not inherited in both the casesnot inherited in both the cases
(publicly/privately inherited).(publicly/privately inherited).
 The private members of a base class willThe private members of a base class will
never become the members of its derivednever become the members of its derived
class.class.
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14. InheritanceInheritance
 In inheritance, some of the base class dataIn inheritance, some of the base class data
elements and member functions are inherited intoelements and member functions are inherited into
the derived class.the derived class.
 We can add our own data and member functionsWe can add our own data and member functions
for extending the functionality of the base class.for extending the functionality of the base class.
 It is a powerful tool for incremental programIt is a powerful tool for incremental program
development.development.

15. Effect of Inheritance on the visibility of MembersEffect of Inheritance on the visibility of Members
Private
Protected
Public
Private
Protected
Public
Private
Protected
Private
Protected
Public Public
Not inheritableNot inheritable
Class B
Class D1 : public B Class D2 : private B
Class X : public D1, protected D2

16. VisibilityVisibility
Base classBase class
visibilityvisibility
Derived class visibilityDerived class visibility
PublicPublic
DerivationDerivation
PrivatePrivate
DerivationDerivation
ProtectedProtected
DerivationDerivation
PrivatePrivate  NotNot
InheritedInherited
NotNot
InheritedInherited
NotNot
InheritedInherited
ProtectedProtected  ProtectedProtected PrivatePrivate ProtectedProtected
PublicPublic  PublicPublic PrivatePrivate ProtectedProtected

17. class Shapeclass Shape
{{
protected:protected:
float width, height;float width, height;
public:public:
void set data (float a, float b)void set data (float a, float b)
{{
width = a; height = b;width = a; height = b;
}}
};};
class Rectangle: public Shapeclass Rectangle: public Shape
{{
public:public:
float area ()float area ()
{{
return (width * height);return (width * height);
}}
};};
class Triangle: public Shapeclass Triangle: public Shape
{{
public:public:
float area ()float area ()
{{
return (width * height) / 2;return (width * height) / 2;
}}
};};
int main ()int main ()
{{
Rectangle rect; Triangle tri;Rectangle rect; Triangle tri;
rect.set data (5,3);rect.set data (5,3);
tri.set data (2,5);tri.set data (2,5);
cout << rect.area() << endl;cout << rect.area() << endl;
cout << tri.area() << endl;cout << tri.area() << endl;
return 0;return 0;
}}
Output: 15Output: 15
55

18. Resolution in InheritanceResolution in Inheritance
class Aclass A
{{
public:public:
void display ()void display ()
{ cout << “Class A n“;}{ cout << “Class A n“;}
};};
class B : public Aclass B : public A
{{
public:public:
void display ()void display ()
{ cout << “Class B n“;}{ cout << “Class B n“;}
};};
void main( )void main( )
{{
B b;B b;
b.display( );b.display( ); // in B// in B
b.A::display( );b.A::display( ); // in A// in A
b.B::display( );b.B::display( ); // in B// in B
}}
continue …

19. Thank YouThank You