Steps in Programme Development

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CH -1

STEPS IN PROGRAMDEVELOPMENT

Mr. Soumen Saha

Master School of Management


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Let us start with a simpleproblem: To find the Additionof two number

The steps are

Read the two numbers

Add these two numbers,producing the sum

Print out the sum

INTRODUCTION TO

PROGRAMMING LANGUAGE


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Since the computer cannotunderstand instructions in theEnglish language some special

languages must be used for writingthe instructions. These speciallanguages are called ProgrammingLanguages.

Instructions written in aprogramming language constitutewhat is known as a program.

The person who writes the program

PROGRAMMING LANGUAGE


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Problem identification. Division of the problem into smaller part

known as tasks and the analysis of thesetasks.

Analysis of the data and validation of thedata that will be used in the problem

Input/output specifications. Design of the algorithm for the solution of

the problem.

Coding of the algorithm in a languageunderstood by a computer. Implementation of the program, including

testing and debugging. Documentation of the program.

Use of the program and possiblemodifications.

STEPS FOLLOWED WHEN

DEVELOPING PROGRAM


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Need to be absolutely clear aboutwhat the problem really is.

Have to identify and define

unambiguous terms in the problem.

Identify the root of the problem notthe symptom.

The problem has to be viewed in itsentirety and not in fragments.

PROBLEM IDENTIFICATION


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A programming problem (tasks) canalmost be broken into a number ofsub-problems (sub tasks).

It is because

Sub-task is always smaller than theoriginal task and hence easier to

manage and solve. (the principle ofdivide and conquer)

The sub-tasks can be solved in

parallel, perhaps by assigningdifferent sub-tasks to different

TASKS AND TASKSANALYSIS


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A program transforms input data intooutput data. Data analysis startswith reviewing the collected data.Finding meaning in the data is veryimportant. Before settling down towrite the code, we must take acritical look at each and everypiece of data and the metadata.

GIGO (garbage-in equals garbage-out) is the fact. We get meaningfulresults from the machine if andonly if the input to the machine is

meaningful, and a wrong(incorrect) data input produces

DATA ANALYSIS ANDDATA VALIDATION


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Before coding the programmer mustbe supplied with detailed input-output specifications of theprogram. There should be a preciseand unambiguous description of

What constitute the input data. Format of the data

Physical medium of input Format of the output. Physical medium of output

INPUT / OUTPUT

SPECIFICATIONS


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It is a set of instruction which,

when followed in a predeterminedsequence, leads to the solution of agiven problem in a finite number ofsteps.

An algorithm should satisfy thefollowing criteria:

There should be input (s). There should be at least one output. Each instruction should be unambiguous. There should not be any uncertainty about

which instruction is to be executed next. Algorithm should be terminate after a

finite number of steps.Some of the tools of al orithm are

DESIGN OF ALGORITHM


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it refers to writing statementsaccording to the algorithmfollowing the syntax of theprogramming language at

hand. Of course the rightchoice of the language for thecoding is an important issue.

CODING


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It is but natural to make mistakes inprogramming. Before running theprogram it is good practice to sitdown with a pencil and paper andtrace the execution of the programwith some sample data.

By a careful study of the programsthe syntax errors or/and semantic(logical) errors can be detected.

Syntax errors are pointed out by thecomputer and are thus easy torectify. But we cannot expect thecomputer to catch semantic errors

in our programs.

IMPLIMENTATION OF PROGRAM


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When the program has a logicalerror, we say that it has abug.

The rectification activity of bugis known as debug.

Testing and debugging are not

same. Testing tells us theexistence of error(s) anddebugging is the process of

removing the error(s).

TESTING & DEBUGING


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Two types of approaches are applied totest a program

Black box testing: also known asfunctional testing, is a testing

technique where the tester neverexamine the project code and doesnot need further knowledge of theprogram other than its specifications.The tester should only know about theinputs and the expected outcomes.

White box testing: also known asglass box, structural, clear box andopen box testing. Here explicit

knowledge of the internal workings of

TESTING APPROACHES


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Documentation is an integral part of theprogram development process. It refers toall written material that helps to explainthe use and maintenance of a system orprogram.

Proper documentation enables the user tounderstand the program and acts as areference tool for programmers.

In case modifications are required, it iseasier to understand the logic of a

program from documented records ratherthan the code.Documents for the users are system

manuals, user manuals, online help etcDocuments for developers are comments in

the program, visual appearance of code,various reports, programming tools like

PROGRAM DOCUMENTATION


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Programs, once developed, remain inuse for a period of time. And in futuremodification of the program mayrequired due to

Change in external factors ofrequirement of the program.

May have some bug in the program

found later while using it. To improve the program.

USE AND MODIFICATION OFPROGRAM


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??Thank u

Steps in Programme Development

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