IET307 OOP - object oriented programming concepts.pptx
- 1. Object Oriented Programming OOP Concepts Comparison of OOP & POP
- 2. Procedure Oriented Programming • Problem is viewed as a sequence of things to be done such as reading, calculating and printing • A number of functions are written to accomplish various tasks • Many important data items are placed as global – they are vulnerable to accidental changes by functions
- 3. Typical structure of procedure oriented programs
- 4. Relationship Between Data and Functions in POP
- 5. Procedure Oriented Programming • In a large program, it is very difficult to identify which data belong to which function • For an external data structure to be revised, all functions that access the data need to be revised • This increases opportunity for bugs to creep in • POPs do not model real world problems very well
- 6. Comparison of OOP and POP Procedure Oriented Programming Object Oriented Programming Program is divided into small parts called functions. Program is divided into parts called objects. Importance is not given to data but to functions as well as sequence of actions to be done. Importance is given to the data rather than procedures or functions Follows Top Down approach. Follows Bottom Up approach Does not have any access specifier. Has access specifiers named Public, Private and Protected Data can move freely from function to function in the system Objects can move and communicate with each other through member functions.
- 7. Comparison of OOP and POP contd.. Procedure Oriented Programming Object Oriented Programming To add new data and function is not easy Provides an easy way to add new data and function. Most function uses Global data for sharing that can be accessed freely from function to function in the system. Data can not move easily from function to function. It can be kept public or private, so we can control the access of data. Does not have any proper way for hiding data; so it is less secure. Provides Data Hiding. which gives more security to data Overloading is not possible. Overloading is possible in the form of Function Overloading and Operator Overloading Example of Procedure Oriented Programming languages : C, FORTRAN, Pascal, VB Example of Object Oriented Programming Languages : C++, JAVA, Simula, Smalltalk, VB.NET, C#.NET, Ada
- 8. Object Oriented Programming Definition OOP can be defined as an approach that provides a way of modularizing programs by creating partitioned memory area for both data and functions, that can be used as templates for creating copies of such modules on demand.
- 9. Features of Object Oriented Programming • Treats data as critical element and does not allow it to flow freely around the system. • Programs are divided into entities known as objects • Data and functions are built around these objects • Data and the functions that operate on them are tied together • Data is hidden and cannot be accessed by external functions • Objects may communicate with each other through functions • New data and functions can be easily added whenever necessary
- 10. Fundamental Concepts of OOP • Object • Class • Method • Modularity • Data abstraction • Encapsulation • Hierarchy • Inheritance • Polymorphism • Dynamic Binding • Message Passing • Reusability • Delegation • Genericity
- 11. Object • Is a partitioned area of computer memory that stores data and the set of operations that can access that data • Basic run-time entities in OOP • Represent real-world entities like a person, a bank account , a list etc. • Programming problem is analyzed in terms of objects and the nature of communication between them • Objects take up space in memory and have an associated address
- 12. Class • Is a group of objects having identical properties, common behaviour and shared relationship • Is a user-defined datatype • The entire group of data and code of an object is built using class - class is a model of the object • Objects are nothing but variables of the type class
- 13. Method • An operation required for an object or entity when coded in a class is called a method • Class member functions • Data members of any class uses its member functions or methods to perform operation
- 14. Modularity • Modularity refers to an organizing structure in which different components of a software system are divided into separate functional units. • The various components can work together to form a single functioning unit; but sometimes they can perform alone as a complete function, if not connected with each other.
- 15. Data Abstraction • Refers to representing essential features without including background details. • Classes use the concept of abstraction and are defined as a list of abstract attribute ( data members) and functions ( member functions) to operate on these attributes.
- 16. Encapsulation • This is the wrapping up of data and functions into a single unit ( called class ) . • This restricts access to data from the outside world; only those functions wrapped in the class can access it • This insulation of data from direct access by the program is called data hiding
- 17. Hierarchy • Hierarchy refers to an organizational structure in which items are ranked in a specific manner, usually according to levels of importance. • Data hierarchy is the structure and organization of data in a database • Class hierarchy refers to a family of classes obtained through inheritance
- 18. Inheritance • Process by which objects of one class acquire the properties of objects of another class • It supports the concept of hierarchical classification • A derived class shares common characteristics with the base class • Through inheritance reusability is achieved • Additional features can be added to an existing class without modifying it or having to rewrite its code in the new class
- 19. Polymorphism • Means the ability to take more than one form • An entity may exhibit different behaviours in different instances • In C++, polymorphism is achieved through operator overloading and function overloading • Making an operator with operands of basic datatype do the same operation with user-defined datatypes is called operator overloading • Using the same function name for defining different function is called function overloading
- 20. Dynamic Binding • Binding is the linking of a function call to the function to be executed in response to the call • Normally, function calls are linked to specific functions during compile time (early binding). • In dynamic binding (late binding), the function code associated with a given call is not known until the time of call during run-time. • It is associated with polymorphism
- 21. Message Passing • Object oriented programs consist of a set of objects that communicate with each other • Objects communicate by passing messages • Message for an object is a request for execution of a procedure and will invoke a function in the receiving object • Message passing involves specifying the name of the object, the name of the function and the information to be sent
- 22. Reusability • OOP allows reusability of classes by extending their features to other classes using inheritance. • Reusability saves time and effort
- 23. Delegation • Two classes can be joined by either inheritance or by delegation In inheritance, one class is derived from another In delegation, object of one class is used as data member of another class
- 24. Genericity • This feature allows declaration of variables without specifying exact data type • Compiler identifies the data type at run time • A function that can be used for any type of data can be created • Template feature in C++ allows generic programming
- 25. Advantages of OOP • Object oriented programs can be easily upgraded from small to large systems • Through inheritance, redundant code can be eliminated and extend the use of existing classes • Data hiding facilitates design and development of secure programs that cannot be invaded by code in other parts of the program • Easy to partition the work in a project based on objects • Software complexity can be easily managed
- 26. Applications of OOP The promising areas of application of OOP include • Simulation and modelling • Object –oriented databases • AI and expert systems • Neural network and parallel programming • Decision support and office automation systems • CIM/CAD/CAM systems • Real-time systems • Hypertext, hypermedia and expertext