Computer Programming

Why Programming?
The Programming Process
What Programmers do?
Programming as a Career
Level of Programming Languages
Computer Languages

1. Computer
Programming
Syed Zaid Irshad

2. Outline
–Why Programming?
–The Programming Process
–What Programmers do?
–Programming as a Career
–Level of Programming Languages
–Computer Languages

3. Why Programming?
–Programminghelpsyouunderstandcomputers.
–Acomputerisonlyatool.Ifyoulearnhowtowritesimpleprograms,youwillgainmore
knowledgeabouthowacomputerworks.
–Writingafewsimpleprogramsincreasesyourconfidencelevel.
–Manypeoplefindgreatpersonalsatisfactionincreatingasetofinstructionsthatsolvea
problem.
–Learningprogrammingletsyoufindoutquicklywhetheryoulikeprogrammingand
whetheryouhavetheanalyticalturnofmindprogrammersneed.
–Evenifyoudecidethatprogrammingisnotforyou,understandingtheprocesscertainly
willincreaseyourappreciationofwhatprogrammersandcomputerscando.

4. The Programming Process
–There are five main ingredients in the programming process:
–Defining the problem
–Planning the solution
–Coding the program
–Testing the program
–Documenting the program

5. The Programming Process
–Defining the problem
–Identifyingwhatitisyouknow(input-givendata),andwhatitisyouwanttoobtain
(output-theresult).
–Eventually,youproduceawrittenagreementthat,amongotherthings,specifiesthe
kindofinput,processing,andoutputrequired.
–Thisisnotasimpleprocess.
–Planning the solution
–It is a map of what your program is going to do and how it is going to do it.

6. The Programming Process
–Coding the program
–Youwilltranslatethelogicfromtheflowchartorpseudocode-orsomeothertool-toa
programminglanguage.
–Aswehavealreadynoted,aprogramminglanguageisasetofrulesthatprovidesawayof
instructingthecomputerwhatoperationstoperform.
–Testing the program
–Programmayhavesomeimperfectionsforthenewprogrammers.So,theprogrammers
usefollowingstepstoovercome.
–Desk-Checking
–Translating
–Debugging

7. The Programming Process
–Documenting the program
–Documentingisanongoing,necessaryprocess,although,asmanyprogrammersare,
youmaybeeagertopursuemoreexcitingcomputer-centredactivities.
–Documentationisawrittendetaileddescriptionoftheprogrammingcycleand
specificfactsabouttheprogram.
–Typicalprogramdocumentationmaterialsincludetheoriginandnatureofthe
problem,abriefnarrativedescriptionoftheprogram,logictoolssuchasflowcharts
andpseudocode,data-recorddescriptions,programlistings,andtestingresults.

8. What Programmers do?
–Ingeneral,theprogrammer'sjobistoconvertproblemsolutionsintoinstructionsfor
thecomputer.
–Theprogrammerpreparestheinstructionsofacomputerprogramandrunsthose
instructionsonthecomputer,teststheprogramtoseeifitisworkingproperly,andmakes
correctionstotheprogram.
–Theprogrammeralsowritesareportontheprogram.
–Theseactivitiesarealldonetohelpauserfillaneed,suchaspayingemployees,billing
customers,oradmittingstudentstocollege.
–Theprogrammingactivitiesjustdescribedcouldbedone,perhaps,assoloactivities,
butaprogrammertypicallyinteractswithavarietyofpeople.

9. Programming as a Career
–Althoughmanypeoplemakecareerchangesintothecomputerfield,fewchooseto
leaveit.
–Surveysofcomputerprofessionals,especiallyprogrammers,consistentlyreportahigh
levelofjobsatisfaction.
–Thereareseveralreasonsforthiscontentment.Oneisthechallenge-mostjobsinthe
computerindustryarenotroutine.
–Anotherissecuritysinceestablishedcomputerprofessionalscanusuallyfindworkand
thatworkpayswell-youwillprobablynotberich,butyoushouldbecomfortable.

10. Level of Programming
Languages
–There are five(5) levels or generations of programming languages:
–Machine language
–Assembly languages
–High-level languages
–Very high-level languages
–Natural languages

11. Level of Programming
Languages
–Machine language
–Humansdonotliketodealinnumbersalone-theypreferlettersandwords.But,
strictlyspeaking,numbersarewhatmachinelanguageis.
–Thislowestleveloflanguage,machinelanguage,representsdataandprogram
instructionsas1sand0sbinarydigitscorrespondingtotheonandoffelectrical
statesinthecomputer.
–Eachtypeofcomputerhasitsmachinelanguage.Intheearlydaysofcomputing,
programmershadrudimentarysystemsforcombiningnumberstorepresent
instructionssuchasaddandcompare.
–Primitivebytoday'sstandards,theprogramswerenotconvenientforpeopletoread
anduse.Thecomputerindustryquicklymovedtodevelopassemblylanguages.

12. Level of Programming
Languages
–Assembly languages
–Assemblylanguagesareconsideredverylowlevel-thatis,theyarenotasconvenientfor
peopletouseasmorerecentlanguages.
–Atthetimetheyweredeveloped,however,theywereconsideredagreatleapforward.To
replacethe1sand0susedinmachinelanguage,assemblylanguagesusemnemonic
codes,abbreviationsthatareeasytoremember:AforAdd,CforCompare,MPfor
Multiply,STOforstoringinformationinmemory,andsoon.
–AlthoughthesecodesarenotEnglishwords,theyarestillfromthestandpointofhuman
convenience-preferabletonumbers(0sand1s)alone.
–Furthermore,assemblylanguagespermittheuseofnames-perhapsRATEorTOTAL-for
memorylocationsinsteadofactualaddressnumbers.
–Justlikemachinelanguage,eachtypeofcomputerhasitsassemblylanguage.

13. Level of Programming
Languages
–High-level languages
–Thefirstwidespreaduseofhigh-levellanguagesintheearly1960stransformed
programmingintosomethingquitedifferentfromwhatithadbeen.
–ProgramswerewritteninanEnglish-likemanner,thusmakingthemmoreconvenient
touse.
–Asaresult,aprogrammercouldaccomplishmorewithlesseffort,andprograms
couldnowdirectmuchmorecomplextasks.
–Theseso-calledthird-generationlanguagesspurredthegreatincreaseindata
processingthatcharacterizedthe1960sand1970s.

14. Level of Programming
Languages
–Very high-level languages
–Thefirstisthattheymakeatruebreakwiththepriorgeneration-theyarenon-
procedural.
–Aprocedurallanguagetellsthecomputerhowataskisdone:Addthis,comparethat,
dothisifsomethingistrue,andsoforth-averyspecificstep-by-stepprocess.
–Thefirstthreegenerationsoflanguagesareallprocedural.Inanonprocedural
language,theconceptchanges.Here,usersdefineonlywhattheywantthecomputer
todo;theuserdoesnotprovidethedetailsofjusthowitistobedone.
–Itisaloteasierandfasterjusttosaywhatyouwantratherthanhowtogetit.This
leadsustotheissueofproductivity,akeycharacteristicoffourth-generation
languages.

15. Level of Programming
Languages
–Natural languages
–Theword"natural"hasbecomealmostaspopularincomputingcirclesasithasinthesupermarket.
–Fifth-generationlanguagesare,asyoumayguess,evenmore,ill-definedthanfourth-generationlanguages.
–Theyaremostoftencallednaturallanguagesbecausetheyresemblethe"natural"spokentheEnglishlanguage,and,tothe
managernewtocomputersforwhomtheselanguagesarenowaimed,naturalmeanshuman-like.
–Insteadofbeingforcedtokeycorrectcommandsanddatanamesinthecorrectorder,amanagertellsthecomputerwhattodo
bykeyinginhisorherownwords.
–Amanagercansaythesamethinganynumberofways.Forexample,"GetmetennisracketsalesforJanuary"worksjustaswell
as"IwantJanuarytennisracketrevenues.“
–Sucharequestmaycontainmisspeltwords,lackarticlesandverbs,andevenuseslang.
–Thenaturallanguagetranslateshumaninstructions-badgrammar,slang,andall-intocodethecomputerunderstands.
–Ifitisnotsurewhattheuserhasinmind,itpolitelyasksforfurtherexplanation.

16. Computer Languages
–There are 7 categories of computer languages:
–Machine and assembly languages
–Algorithmic languages
–Business-oriented languages
–Computer programming language
–Education-oriented languages
–Object-oriented languages
–World wide web display languages