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  2. 2. PROGRAMMING Creating algorithms is theprecursor to creating programs;An algorithm is the blueprint, soto speak, of a computer program.
  3. 3. Recall that the general problem-solving process has 5 phases 1.Defining the problem 2.Analysing the problem 3.Identifying and Evaluating Possible Solutions 4.Selection and Justification of the Optimal Solution 5.Implementation and Review
  4. 4. In phase 5 the organisation gets a new system This system is made up of hardware, software, people and proceduresThe process of creating this new system is called the SDLC
  5. 5. SDLC means the ... SystemsDevelopment Life Cycle
  6. 6. TheSystems Development Life Cycleis therefore something of a sub-process inside a larger overall process
  7. 7. The Systems Development Life Cycle is a model used to guide Information Technology professionals through themanagement of InformationTechnology projects to create a new computer system
  8. 8. The Phases in theSystems Development Life Cycle are : 1.Feasibility Study 2.Analysis 3.Design 4.Implementation 5.Testing 6.Maintenance
  9. 9. The SDLC
  10. 10. "Implementation and Review" therefore, isalso done in stages.Note carefully that the SDLC may mean :- implementing a system which uses ageneral purpose computer program or- implementing a system that uses anothertype of off-the-shelf or pre-existing package
  11. 11. or it may mean- implementing a system thatrequires the organisation toemploy/use a programmer or ateam of programmers or asoftware house to create acustom-written softwarepackage
  12. 12. If the organisation chooses to buy apre-existing computer softwarepackage, it simply has to be purchasedand installed, and the staff trained touse it.They may also have to carry outconversion activites i.e. somehowcopying the data they presently haveinto the new program
  13. 13. However, if the software tomeet the organisations needsdoes not presently exist, then in the "implemtation and review" stage of problem solving, a new software package has to be created.
  14. 14. In such cases the SDLC is more than just putting asystem in place but would also have to involve creating a new software package.
  15. 15. Creating a new software package means that theproject involves more than just systems analysts, it also needs programmers
  16. 16. Systems analysts evaluatethe information technology needs of an organisation and prescribe and design new systems for them.
  17. 17. Computer programmers,on the other hand, develop and maintain theinstructions to a computer (software) which are written in a computer language
  18. 18. Computer programmers take instructions fromsystems analysts as to whatthe computer program is to look like and what it is to do
  19. 19. Working together they carry out aparticular variant ofthe SDLC called the PDLC
  20. 20. The process ofcreating new software is called the Program Development Life Cycle
  21. 21. Program Development Life Cycle The progam development life cycle is the process of developing a software according to the desired needs of a user by following a basic set of procedures
  22. 22. While the SDLC is about the entire system, the Program Development Life Cycleis concerned principally with how a new software program comes into being and is continually maintained over its lifetime
  23. 23. Program Development Life CycleThe progam development lifecycle involves •users •systems analysts •programmers and •testers
  24. 24. Program Development Life CycleThe steps in program development are : 1.Requirements Definition 2.Design 3.Implementation / Coding 4.Testing 5.Maintenance
  25. 25. Program Development Life Cycle
  26. 26. Program Development Life CycleStep 1 1.Requirements DefinitionA requirement is a document whichdetails the needs of a customer in aservice or a product
  27. 27. Program Development Life CycleStep 1 1.Requirements DefinitionThis is a critical component in the process.Users often have a vague idea of what theywant in a program. It is the analysts job tohelp them to flesh out these ideas
  28. 28. Program Development Life CycleStep 1 1.Requirements DefinitionRequirements definition is the processof eliciting and documenting what theusers need in a computer program
  29. 29. Program Development Life CycleStep 1 1.Requirements DefinitionIncomplete or inaccurate requirementsresult in schedule delays, wastedresources and customer dissatisfaction
  30. 30. Program Development Life CycleStep 1 1.Requirements DefinitionAt the end of the requirementsdefinition phase the systems analystproduces a document called thesystem specifications
  31. 31. Program Development Life CycleStep 2 2. DesignIn the design phase of the ProgramDevelopment Life Cycle the systemsdeveloper/software engineer creates thealgorithm.The algorithm may be expressed aspseudocode and/or flowcharts
  32. 32. Program Development Life CycleStep 2 2. DesignThey may use techniquse such as •modular programming •top down design •bottom up design •structured programming
  33. 33. Program Development Life CycleStep 3 3. Implementation/CodingCoding means translating the algorithm intocomputer language format. The programmerswho do this are also responsible for testingtheir results to ensure, in particular, that itcontains no syntax errors
  34. 34. Program Development Life CycleStep 4 4. TestingThe program is given to a group ofspecialist testers and/or a group of userrepresentatives who run it and verifythat it performs according to thespecifications developed in step 1
  35. 35. Program Development Life CycleStep 5 5. MaintenanceOver the life of a program, user needsor statutory requirements will meanthat the program needs to be amendedsometimes. This is what maintenance isabout.
  36. 36. Program Development Life CycleDocumentationSome books list documentation as a separatestep in the process and some do not.This is because documentation takes placeover the life of the project. As one works everystep of the way everything should bedocumented.
  37. 37. The PDLC is a cyclical process
  38. 38. THE END