Fifth Chapter Lesson-8: Program Design Model.

At the end of this lesson-

  • 1.You will be able to explain program design model.
  • 2. You will be able to explain structured or procedure programming model.
  • 3. You will be able to explain object oriented programming model.
  • 4. You will be able to explain visual programming model.
  • 5. You will be able to explain event driven programming model.


Program Design Model: Some special rules or methods or processes are followed by the programmer to develop a program to make it more efficient and easier to understand and modify.These rules or processes or methods are called program design model. Some popular program design models are-

  • 1. Structured or procedure programming model
  • 2. Object Oriented Programming model
  • 3. Visual programming model
  • 4. Event driven programming model


Structured or procedure programming model: Structured programming was first suggested in 1966 by Corrado Bohm and Guiseppe Jacopini. The two mathematicians demonstrated that any computer program can be written with just three structures: decisions, sequences, and loops.  In the late 1960s-early 1970s, Edsger W.Dijkstra developed structural programming functionality as a widely used method, in which a program is divided into multiple sections or module with multiple exits and one access point. Each module is called function. In this case, among the modules or functions, there is at least a main function that can call all other functions, each function can call another function but no function can call the main function. Structured programming frequently employs a top-down design model. Structured programming is instruction based programming. That means in this approach data of a program is controlled by instructions.

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The languages that support Structured programming approach are C,COBOL, Pascal, Fortran etc

Advantages of Structured Programming:

  • 1. Development is easier as it requires less effort and time
  • 2. Easier to read and understand
  • 3. Easier to Maintain
  • 4. As program is divided into different modules, so a module can be used multiple times.
  • 5. Easier to Debug


Object Oriented Programming model: Object-oriented programming (or OOP) is a paradigm or pattern of programming whereby the solution to a programming problem is modeled as a collection of collaborating objects. Objects collaborate by sending messages to each other. An object can be defined as a data field that has unique attributes and behavior. Object oriented programming aims to implement real world entities like inheritance, hiding, polymorphism etc in programming. The main aim of OOP is to bind together the data and the functions that operates on them so that no other part of code can access this data except that function. OOP is data based programming approach. That means in this approach, instructions of a program are controlled by data. C++, C#, Java, Python etc are examples of OOP supported languages. Different characteristics of an Object Oriented Programming language:

Object: An object is an entity that possesses both state (or properties or attributes) and behavior. An example of an object is a car. A car has attributes (colour, size, weight, fuel capacity, number of passengers, etc). A car has behavior represented by its methods (start engine, turn left/right, accelerate, stop, turn on wipers, etc).

Class: Class is a blueprint of data and functions or methods. Class does not take any space.

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Encapsulation: Wrapping up of data and functions into a single unit is known as encapsulation. The data is not accessible to the outside world and only those functions which are wrapping in the class can access it.

Polymorphism: Polymorphism means ability to take more than one form. An operation may exhibit different behaviors in different instances. The behavior depends upon the types of data used in the operation.

Inheritance: Inheritance is the process by which one class can acquire the properties of another class. Inheritance provides re usability.


Visual programming model: A visual programming is such a programming approach in which graphical elements and figures are used to develop a program. Visual programming is developed based on structured and object oriented programming. 


Event driven programming model: Event-driven programming is a programming paradigm in which flow of the program is determined by the occurrence of events such as user actions (mouse clicks, key presses),  sensor outputs, or messages from other programs or threads.These events are monitored by code known as an event listener. If it detects that an assigned event has occurred, it runs an event handler(a callback function or method that is triggered when the event occurs).


Lesson Evaluation-

Knowledge Based Questions:

  • a. What is program design model?
  • a. What is structured programming?
  • a. What is OOP?
  • a. What is class?
  • a. What is encapsulation?
  • a. What is polymorphism?
  • a. What is inheritance? 
  • a. What is visual programming?
  • a. What is event-driven programming?

Comprehension Based Questions:

Creative Questions:

Multiple Choice Questions:


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