Introduction

1. COMPUTING AND PROGRAMMING
FUNDAMENTAL
Sherin Rappai
Assistant Professor
Department of Computer Science

2. What is program
• A program, in the context of computer science and software development, refers to
a set of instructions that tell a computer how to perform a specific task or a series
of tasks. Programs are written in programming languages and provide a way for
humans to communicate with computers, directing them to carry out various
operations, calculations, data processing, and interactions.
• Programs can range from simple scripts that automate repetitive tasks to complex
applications that power software systems, games, websites, and more. They are
fundamental to the functioning of computers and enable them to perform a wide
range of functions.

3. • Here are a few key points about programs:
1.Programming Languages: Programs are written using programming languages
such as Python, Java, C++, JavaScript, Ruby, and many others. Each language has
its own syntax and rules that developers follow to create programs.
2.Source Code: The human-readable version of a program is called the "source
code." It consists of statements, commands, and structures that describe the logic
and behavior of the program.
3.Compilation or Interpretation: Depending on the programming language,
programs are either compiled or interpreted. Compiled languages are translated into
machine code before execution, while interpreted languages are executed line by
line by an interpreter.

4. 4.Functionality: Programs can have a wide range of functionalities. They can process data,
perform calculations, manipulate text and images, interact with databases, create user
interfaces, and more.
5.Applications: Programs can be standalone applications (such as word processors, web
browsers, and games) or components of larger systems (such as backend services for web
applications).
6.Algorithms: Programs incorporate algorithms, which are step-by-step procedures for
solving specific problems or performing tasks.
7.Software Development: Creating programs involves the software development process,
which includes phases like analysis, design, coding, testing, deployment, and maintenance.
8.User Interaction: Many programs have user interfaces that allow users to interact with
the software, providing input and receiving output.

5. Program Development Life Cycle

6. • Defining the Problem/Analze – The first step is to define the problem. In major software projects,
this is a job for system analyst, who provides the results of their work to programmers in the form
of a program specification. The program specification defines the data used in program, the
processing that should take place while finding a solution, the format of the output and the user
interface.
• Designing the Program – Program design starts by focusing on the main goal that the program is
trying to achieve and then breaking the program into manageable components, each of which
contributes to this goal. This approach of program design is called top-bottom program
design or modular programming. The first step involve identifying main routine, which is the one
of program’s major activity. From that point, programmers try to divide the various components of
the main routine into smaller parts called modules. For each module, programmer draws a
conceptual plan using an appropriate program design tool to visualize how the module will do its
assign job.

7. • Program Design Tools: The various program design tools are described below:
• Pseudocode – A pseudocode is another tool to describe the way to arrive at a
solution. They are different from algorithm by the fact that they are expressed in
program language like constructs.
• Structure Charts – A structure chart, also called Hierarchy chart, show top-
down design of program. Each box in the structure chart indicates a task that
program must accomplish. The Top module, called the Main module or Control
module. For example

8. • Algorithms – An algorithm is a step-by-step description of how to
arrive at a solution in the most easiest way.
• Flowcharts – A flowchart is a diagram that shows the logic of the
program. For example:

9. • Coding the Program – Coding the program means translating an algorithm into
specific programming language. The technique of programming using only well
defined control structures is known as Structured programming. Programmer must
follow the language rules, violation of any rule causes error. These errors must be
eliminated before going to the next step.
• Testing and Debugging the Program – After removal of syntax errors, the
program will execute. However, the output of the program may not be correct.
This is because of logical error in the program. A logical error is a mistake that the
programmer made while designing the solution to a problem. So the programmer
must find and correct logical errors by carefully examining the program output
using Test data. Syntax error and Logical error are collectively known as Bugs.
The process of identifying errors and eliminating them is known as Debugging.

10. • Documenting the Program – After testing, the software project is almost
complete. The structure charts, pseudocodes, flowcharts and decision
tables developed during the design phase become documentation for others who
are associated with the software project. This phase ends by writing a manual that
provides an overview of the program’s functionality, tutorials for the beginner, in-
depth explanations of major program features, reference documentation of all
program commands and a thorough description of the error messages generated by
the program.
• Deploying and Maintaining the Program – In the final phase, the program is
deployed (installed) at the user’s site. Here also, the program is kept under watch
till the user gives a green signal to it. Even after the software is completed, it
needs to be maintained and evaluated regularly. In software maintenance, the
programming team fixes program errors and updates the software.

11. Advantages of PDLC
• Facilitates communication: PDLC helps to facilitate communication between
different stakeholders, such as developers, project managers, and customers.
• Identifies and manages risks: PDLC helps to identify and manage potential risks
during the development of the program, allowing for proactive measures to be
taken to mitigate them.
• Improves quality: PDLC helps to improve the quality of the final product by
providing a systematic approach to testing and quality assurance.
• Increases efficiency: By following a PDLC, the development process becomes
more efficient as it allows for better planning and organization.

12. Disadvantages of PDLC
• Can be time-consuming: Following a strict PDLC can be time-consuming, and
may delay the development of the program.
• Can be inflexible: The rigid structure of PDLC may not be suitable for all types of
software development projects, and may limit the ability to incorporate changes or
new ideas.
• Can be costly: Implementing a PDLC may require additional resources and
budget, which can be costly for organizations.
• Can be complex: PDLC can be complex, and may require a certain level of
expertise and knowledge to implement effectively.
• May not be suitable for smaller projects: PDLC may not be suitable for smaller
projects as it can be an overkill and would not be cost-effective.

13. What is algorithm
• An algorithm is a set of instructions for solving a problem or accomplishing a
task. (or)
• An algorithm is an effective method and self-contained step-by-step set of
operations to be perform a task in finite amount of time and space.
• Algorithm refers to a sequence of finite steps to solve a particular problem.

14. What is the need for algorithms
1.Algorithms are necessary for solving complex problems efficiently and
effectively.
2.They help to automate processes and make them more reliable, faster, and easier
to perform.
3.Algorithms also enable computers to perform tasks that would be difficult or
impossible for humans to do manually.
4.They are used in various fields such as mathematics, computer science,
engineering, finance, and many others to optimize processes, analyze data, make
predictions, and provide solutions to problems.

15. Characteristics of algorithm

16. • Clear and Unambiguous: The algorithm should be unambiguous. Each of its steps should be clear
in all aspects and must lead to only one meaning.
• Well-Defined Inputs: If an algorithm says to take inputs, it should be well-defined inputs. It may
or may not take input.
• Well-Defined Outputs: The algorithm must clearly define what output will be yielded and it
should be well-defined as well. It should produce at least 1 output.
• Finite-ness: The algorithm must be finite, i.e. it should terminate after a finite time.
• Feasible: The algorithm must be simple, generic, and practical, such that it can be executed with
the available resources. It must not contain some future technology or anything.
• Language Independent: The Algorithm designed must be language-independent, i.e. it must be
just plain instructions that can be implemented in any language, and yet the output will be the
same, as expected. An algorithm must be developed by using very basic, simple, and feasible
operations so that one can trace it out by using just paper and pencil.

17. • Advantages of Algorithms:
• It is easy to understand.
• An algorithm is a step-wise representation of a solution to a given problem.
• In an Algorithm the problem is broken down into smaller pieces or steps hence, it
is easier for the programmer to convert it into an actual program.
• Disadvantages of Algorithms:
• Writing an algorithm takes a long time so it is time-consuming.
• Understanding complex logic through algorithms can be very difficult.
• Branching and Looping statements are difficult to show in Algorithms(imp).

18. 1. Get a clear understanding of the problem statement.
2. Proceed in a step by step fashion.
3. Divide the job into parts.
4. Include variables and their usage and define expressions.
5. Outline each loop
6. Include action statements.
7. Work outwards from the Action Statements, figuring out how each parameter will be determined each time the loop goes around
8. Go back to step number if loop or condition fails.
9. Use jump statement to jump from one statement to another.
10. Try to avoid unwanted raw data in algorithm.
11. Use break and stop to terminate the process.
Algorithm Writing

19. • Let us first take an example of a real-life situation for creating algorithm. Here is
the algorithm for going to the market to purchase a pen.

20. • Algorithm to find area of a circle
1. Start
2. Input the value of radius R
3. Let PI=3.14
4. Calculate area=PI*R*R
5. Print area
6.End

21. Algorithm to find if the number is even or odd

22. Flowchart
• A flowchart is a visual representation of the sequence of steps and decisions
needed to perform a process.
• Flowcharts use special shapes to represent different types of actions or steps in a
process.
Types :
I. Sequential Structure – sequential order
II. Selective Structure – condition expression (T/F)
III. Looping Structure – Iteration – repeatedly check condition until false

23. Symbols

24. Symbols cont..

25. Sequential

26. Selective

27. Looping

29. How to draw flowchart
• Input is Number1, Number2
• Output is stored in Sum
• Concentrate on the symbols used.

30. Advantages
• Flowcharts are easier to understand compare to Algorithms and Pseudo
code.
• It helps us to understand Logic of given problem.
• It is very easy to draw flowchart in any word processing software like MS
Word.
• Using only very few symbol, complex problem can be represented in
flowchart.
• Software like RAPTOR can be used to check correctness of flowchart
drawn in computers.
• Flowcharts are one of the good way of documenting programs.
• It helps us in debugging process.

31. Disadvantages
• Manual tracing is needed to check correctness of flowchart drawn on
paper.
• Simple modification in problem logic may leads to complete redraw of
flowchart.
• Showing many branches and looping in flowchart is difficult.
• In case of complex program/algorithm, flowchart becomes very
complex and clumsy.
• Modification of flowchart is sometimes time consuming.

32. Guidelines for flowchart
• Understand a system before flowcharting it.
• Flowchart can have only one start and one stop symbol
• Identify the entities, such as departments, job functions, or external parties that are to be
flowcharted.
• divide the flowchart into columns, label each column
• Use standard flowcharting symbols
• Clearly label all symbols
• Use arrowheads on all flow lines.
• Try to use only one page per flowchart
• On-page connectors are referenced using numbers
• Off-page connectors are referenced using alphabets
• General flow of processes is top to bottom or left to right
• Arrows should not cross each other
• Place the name of the flowchart, the date it was prepared, and the designer's name on each
page of the flowchart.

33. Pseudocodes
• A notation resembling a simplified programming language, used in program design.
• An outline of a program, written in a form that can easily be converted into real programming
statements.
• Pseudocode cannot be compiled nor executed, and there are no real formatting or syntax rules. It is
simply one step - an important one - in producing the final code
• Pseudocode is a "text-based" detail (algorithmic) design tool.
• Include control structures such as WHILE, IF-THEN-ELSE, REPEAT-UNTIL, FOR, and CASE,
which are present in many high level languages

34. Pseudo Guidelines : Rules for Pseudocode
• Write only one statement per line
• Capitalize initial keyword
• Indent to show hierarchy
• End multiline structures
• Keep statements language independent

35. Guidelines Cont…
• 1. Write only one statement per line:
• READ a,b
• 2. Capitalize initial keyword
• READ, WRITE, IF, ELSE, ENDIF, WHILE, ENDWHILE, REPEAT,
UNTIL 3
3. Indent to show hierarchy
SEQUENCE - all starting in the same column.
SELECTION - indent the statements that fall inside the selection structure, but
not the keywords that form the selection
LOOPING- indent the statements that fall inside the loop, but not the keywords
that form the loop

36. Guidelines Cont..
• 4. End multiline structures
• how the IF/ELSE/ENDIF is constructed above. The ENDIF (or END
whatever) always is in line with the IF (or whatever starts the structure).
• 5. Keep statements language independent
• to write in whatever language you are most comfortable with.
• if you are SURE it will be written in that language, then you can use the
features. If not, then avoid using the special features.

37. Benefits/Advantages of Pseudocode
• Can be done easily on a word processor Easily modified
• Clarify algorithms in many cases.
• Impose increased discipline on the process of documenting detailed design. Provide additional level at which inspection can be performed.
• Help to trap defects before they become code.
• Increases product reliability.
• May decreases overall costs.
• It can be easily modified as compared to flowchart.
• Its implementation is very useful in structured design elements.
• It can be written easily.
• It can be read and understood easily.
• Converting a pseudocode to programming language is very easy as compared with converting a flowchart to programming language

38. Disadvanatges
1.Lack of Formal Syntax: Pseudocode lacks a standardized syntax, which can lead to
ambiguity or misinterpretation, especially when different individuals or teams use
different conventions.
2.No Execution Capability: Pseudocode is not executable like actual programming
languages. It cannot be run to validate its correctness, which means errors might only
become apparent during implementation.
3.Subjective Interpretation: Pseudocode can be interpreted differently by different
individuals, leading to inconsistencies in understanding the logic.
4.Limited Portability: Pseudocode doesn't adhere to a specific programming language, so
converting pseudocode into actual code might require additional effort to adapt it to the
chosen language's syntax and features.
5.Level of Detail: Pseudocode might not provide enough detail for complex algorithms or
might become overly detailed for simple ones.