Sams teach yourself perl in 24 hours 3rd edition jun 2005 ISBN 0672327937
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SAMSTeachYourselfPerlin24Hours
THIRDEDITION
ByClintonPierce
...............................................
Publisher:SamsPublishing
PubDate:June15,2005
ISBN:0-672-32793-7
Pages:480
TableofContents|Index
LearnPerlprogrammingquicklyandeasilywith24one-hourlessonsinSamsTeach
YourselfPerlin24Hours,3/e.Thesestep-by-steplessonswillteachyouthebasicsof
Perlandhowtoapplyitinwebdevelopmentandsystemadministration.Plus,the
thirdeditionhasbeenupdatedtoinclude5chaptersonnewtechnologies,information
onthelatestversionofPerlandalookaheadtoPerl6.Youwillfocusonreal-world
development,includinghowto:
EffectivelyusePerlforlargedevelopmentprojectsusingPerlModules.
UsePerlfordataprocessing.
UtilizePerlasa"glue"languagewithotherprogramminglanguages.
UsePerlasawebdevelopmentlanguage.
Theconcise,modularformatoftheSamsTeachYourselfPerlin24Hours,3/eisthe
idealwaytolearnfortoday'sworkingprofessional.
SAMSTeachYourselfPerlin24Hours
THIRDEDITION
ByClintonPierce
...............................................
Publisher:SamsPublishing
PubDate:June15,2005
ISBN:0-672-32793-7
Pages:480
TableofContents|Index
Copyright
AbouttheAuthor
Acknowledgments
WeWanttoHearfromYou!
ReaderServices
Introduction
HowtoUseThisBook
ConventionsUsedinThisBook
PartI.PerlFundamentals
Hour1.GettingStartedwithPerl
InstallingPerl
Documentation
YourFirstProgram
Summary
Q&A
Workshop
Hour2.Perl'sBuildingBlocks:NumbersandStrings
Literals
ScalarVariables
ExpressionsandOperators
MoreOperators
Exercise:InterestCalculator
Summary
Q&A
Workshop
Hour3.ControllingtheProgram'sFlow
Blocks
TheifStatement
Looping
OtherFlowControlTools
Exercise:FindingPrimes
Summary
Q&A
Workshop
Hour4.StackingBuildingBlocks:ListsandArrays
PuttingThingsintoListsandArrays
GettingElementsOutofanArray
ManipulatingArrays
Exercise:PlayingaLittleGame
Summary
Q&A
Workshop
Hour5.WorkingwithFiles
OpeningFiles
Reading
Writing
FreeFiles,TestingFiles,andBinaryData
Summary
Q&A
Workshop
Hour6.PatternMatching
SimplePatterns
TheMetacharacters
Substitution
Exercise:CleaningUpInputData
PatternMatchingOddsandEnds
Summary
Q&A
Workshop
Hour7.Hashes
FillingYourHash
GettingDataOutofaHash
ListsandHashes
HashOddsandEnds
UsefulThingstoDowithaHash
Exercise:CreatingaSimpleCustomerDatabasewithPerl
Summary
Q&A
Workshop
Hour8.Functions
CreatingandCallingSubroutines
Scope
Exercise:Statistics
FunctionFootnotes
Summary
Q&A
Workshop
PartII.AdvancedFeatures
Hour9.MoreFunctionsandOperators
SearchingScalars
Transliteration,NotSubstitution
ABetterWaytoprint
Exercise:AFormattedReport
NewWayswithArrays
Summary
Q&A
Workshop
Hour10.FilesandDirectories
GettingaDirectoryListing
Exercise:TheUnixgrep
Directories
UnixStuff
EverythingYouEverWantedtoKnowAboutTHATFile
Exercise:RenamingFilesEnMasse
Summary
Q&A
Workshop
Hour11.SystemInteraction
Thesystem()Function
CapturingOutput
Pipes
FirstLessoninPortability
Summary
Q&A
Workshop
Hour12.UsingPerl'sCommand-LineTools
WhatIstheDebugger?
Exercise:FindingtheBug
OtherCommand-LineStuff
Summary
Q&A
Workshop
Hour13.ReferencesandStructures
ReferenceBasics
RecipesforStructures
Exercise:AnotherGame,Maze
Summary
Q&A
Workshop
Hour14.UsingModules
AGentleIntroduction
AQuickTour
FullListofStandardModules
Summary
Q&A
Workshop
Hour15.FindingPermanence
DBMFiles
Exercise:AFree-FormMemoPad
TextFilesasDatabases
RandomFileAccess
Locking
Summary
Q&A
Workshop
Hour16.ThePerlCommunity
What'sPerlAllAbout,Anyway?
TheComprehensivePerlArchiveNetwork(CPAN)
YourNextSteps
OtherResources
Summary
Q&A
Workshop
PartIII.ApplyingPerl
Hour17.WritingModules
BuildingaModule
ScopingRevisited
Anotherstatement:our
Example:AModuletoHandleCommonFileInformationRequests
Summary
Q&A
Workshop
Hour18.ObjectPrimer
Classes,Properties,andMethods
Example:ImplementationofCarinPerl
Example:FileInformationClass
Summary
Q&A
Workshop
Hour19.DataProcessing
HowtoLookatData
DealingwithTableData
XMLData
Summary
Q&A
Workshop
Hour20.PerlasaGlueLanguage
WeatherStation
PresentingDataasPDF
ReadingandWritingExcelSpreadsheets
Summary
Q&A
Workshop
Hour21.IntroductiontoCGI
BrowsingtheWeb
Don'tSkipThisSection
YourFirstCGIProgram
WhattoDoWhenYourCGIProgramDoesn'tWork
Summary
Q&A
Workshop
Hour22.BasicForms
HowFormsWork
PassingInformationtoYourCGIProgram
WebSecurity101
AGuestbook
Summary
Q&A
Workshop
Hour23.ComplexForms
TheStatelessWeb
HiddenFields
AMultipageSurvey
Summary
Q&A
Workshop
Hour24.ManipulatingHTTPandCookies
TheHTTPConversation
MoreDetailsonCallingCGIPrograms
Cookies
LongTermCookies
ProblemswithCookies
Summary
Q&A
Workshop
PartIV.Appendixes
AppendixA.InstallingModules
PickingtheRightModule
InstallingtheModulesUnder…
WhattoDoWhenYou'reNotAllowedtoInstallModules
Index
Copyright
Copyright©2005bySamsPublishing
Allrightsreserved.Nopartofthisbookshallbereproduced,storedinaretrieval
system,ortransmittedbyanymeans,electronic,mechanical,photocopying,
recording,orotherwise,withoutwrittenpermissionfromthepublisher.No
patentliabilityisassumedwithrespecttotheuseoftheinformationcontained
herein.Althougheveryprecautionhasbeentakeninthepreparationofthisbook,
thepublisherandauthorassumenoresponsibilityforerrorsoromissions.Noris
anyliabilityassumedfordamagesresultingfromtheuseoftheinformation
containedherein.
LibraryofCongressCatalogCardNumber:2004195543
PrintedintheUnitedStatesofAmerica
FirstPrinting:June2005
080706054321
Trademarks
Alltermsmentionedinthisbookthatareknowntobetrademarksorservice
markshavebeenappropriatelycapitalized.SamsPublishingcannotattesttothe
accuracyofthisinformation.Useofaterminthisbookshouldnotberegarded
asaffectingthevalidityofanytrademarkorservicemark.
WarningandDisclaimer
Everyefforthasbeenmadetomakethisbookascompleteandasaccurateas
possible,butnowarrantyorfitnessisimplied.Theinformationprovidedisonan
"asis"basis.Theauthorandthepublishershallhaveneitherliabilitynor
responsibilitytoanypersonorentitywithrespecttoanylossordamagesarising
fromtheinformationcontainedinthisbook.
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Credits
SeniorEditor
ScottMeyers
ManagingEditor
CharlotteClapp
ProjectEditor
AndyBeaster
CopyEditor
KateGivens
Indexer
ChrisBarrick
Proofreader
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Dedication
ToHeidiandCalvin,fornotkillingmethissummerandsupportingmeduring
thisadventure.Withoutyoursupport,I'dhavelostevenmoreofmymarbles.
AbouttheAuthor
ClintonPierceisasoftwareengineer,freelanceprogrammer,andinstructor.He
hasbeenansweringquestionsaboutPerlonUSENETformanyyearsandhas
beenwritingcoursewareandteachingPerltohisco-workersandanyoneelse
whowilllistenforaboutaslong.Heisasoftwareengineerforapayroll
company,who,whennotdesigningmiddlewaresoftwaretointegratelegacy
systemstotheWeb,navigatingtheintricaciesofpayrolltaxes,teachingUNIX
andPerl,writingbooksandarticles,orwritingprogramsathomeJustForThe
FunOfIt,harborssecretdreamsofbeingabductedbywoodnymphsandliving
inthedeepforestwithouttechnology.YoucanvisithisWebsiteat
forupdatesandcorrections,orjusttosayhello.
Acknowledgments
"IfIhaveseenfurther,itisbystandingontheshouldersofGiants"Isaac
Newton.
AnybookonPerlshouldfirstrecognizetheGiantwhogaveusPerlinthefirst
place.Thanks,Larry.
InotonlystoodontheshouldersofGiants,butalsowasledbyhoardsofothers.
Tomakesurethisbookcameoutaserror-freeaspossible,Iinvitedperfect
strangerstowatch,criticize,andcorrectmewhennecessary.Thishasbeena
humblingexperience.Innoparticularorder,thepeoplewhoannoyedmethe
mostandwhodeservethemostthanksareAbigail,GregBacon,SeanBurke,
KenFox,KevinMeltzer,TomPhoenix,andRandalSchwartz.Also,thanksto
MichaelSchwern,TomGrydeland,MattBielanski,MarkJason-Dominus,Jeff
Pinyan,GaryRoss,AndrewChen,andJohnBellforfindingbugsandoffering
suggestions.Overtheyearshelpfulreadershavebeeninstrumentalinweeding
outsmallproblemswiththetextandhelpingwiththeexplanations,notably:Lisa
M,RobertB,QinglinL,IhorP,DavidK,DanG,andLauraC.
Somesmallcreditshouldalsogoto#perlforlettingmesoundmyideasoffthem
andforgivingmetheirhonestandsometimesbrutalopinions.
SomewhatresponsibleforthisbookareBillCrawfordandDonnaHinklefor
gettingmeintothiswholetrainingmessinthefirstplace.Thanks,Ithink.
Ofcourse,I'dliketothankthepeopleatSamsPublishingwhoputupwithanew
authorandallthepainandagonythatgoeswiththeterritory.Withoutpeople
likeRandiRoger,ScottMeyers,KateGivens,andeveryonebehindthescenes
thatIdidn'tgettotalktobutwhoarejustasimportant,I'dneverhaveput
togetheranythinglikethis.
WeWanttoHearfromYou!
Asthereaderofthisbook,youareourmostimportantcriticandcommentator.
Wevalueyouropinionandwanttoknowwhatwe'redoingright,whatwecould
dobetter,whatareasyou'dliketoseeuspublishin,andanyotherwordsof
wisdomyou'rewillingtopassourway.
Youcanemailorwritemedirectlytoletmeknowwhatyoudidordidn'tlike
aboutthisbookaswellaswhatwecandotomakeourbooksstronger.
PleasenotethatIcannothelpyouwithtechnicalproblemsrelatedtothetopicof
thisbook,andthatduetothehighvolumeofmailIreceive,Imightnotbeable
toreplytoeverymessage.
Whenyouwrite,pleasebesuretoincludethisbook'stitleandauthoraswellas
yournameandphoneoremailaddress.Iwillcarefullyreviewyourcomments
andsharethemwiththeauthorandeditorswhoworkedonthebook.
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Mail:
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AssociatePublisher
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800East96thStreet
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ReaderServices
FormoreinformationaboutthisbookoranotherSamstitle,visitourwebsiteat
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bookintheSearchfieldtofindthepageyou'relookingfor.
Introduction
"Anysufficientlyadvancedtechnologyisvirtuallyindistinguishablefrom
magic."
ArthurC.Clarke
Rememberthiswell:There'snothingmagicalaboutprogrammingacomputer.
Likeanythingthatseemsmagical,there'salwaysatricktoitandprogrammingis
nodifferent.Allyouneedaresomeanalyticalthinkingskills,thedesiretolearn,
andsometimetolearnPerl.Thebestwaytolearnhowtoprogramacomputeror
anytaskreallyistohaveagoal.YourgoalcouldbetospiceupyourWebpages,
convertaprogramyoualreadyhavetoPerl,ortosatisfyidlecuriosityitdoesn't
reallymatter.
Now,giventhatyou'veestablishedagoalandhavesomethinkingskills,what
doesthisbookhaveforyou?
ThisbookwillteachyouthebasicsofthePerlprogramminglanguage.You'll
learnjustenoughPerltodosomethinguseful.Youwillnotbeoverwhelmedwith
detailsthat,althoughinteresting,willonlygetinyourwayandthatyou'll
probablyneveruseagain.Eachnewconceptinthisbookisdemonstratedbylots
ofworkingcodeexamples.Goaheadflipthroughthebookandsee.
ButwhyPerl?Almosteverycompanythatusesprogrammingofsomekinduses
Perl.Perlisfoundinfinance,manufacturing,genetics,themilitary,andevery
otherapplicationknowntohumankind.And,ofcourse,Perlisusedonthe
InternetandtheWorldWideWeb.Perlisn'tgoingawayanytimesoon,whichis
whylearningitisaninvestmentinyourtimethatwillpayoffforyearstocome.
It'salsopossibletocreatereallystunningPerlprogramswithjustasmallbitof
code.UsingalittlebitofPerltogluetogetherotherapplications,languages,and
technologies,you'llbecreatingusefulPerlprogramsinnotime.
HowtoUseThisBook
Thisbookisdividedinto24segmentsthattakeroughlyanhourtocomplete.
Youcanworkthroughthelessonsinthespaceofaday(ifyoudon'tplantoeat
orsleep),oryoucantakeyourtimeandworkthroughthehourlessonsatyour
ownpace.
Attheendofeachhour,you'llbeabletoaccomplishanewsetoftasks.The
lessonscontainclearexplanationsofthelanguagefeaturesandhowtheywork.
Inaddition,eachhourprovidesyouwiththeopportunityforhands-ontraining,
simplybyfollowingthestepsdescribed.
ConventionsUsedinThisBook
SamsTeachYourselfPerlin24Hoursusesanumberofconventionsthatare
consistentthroughoutthisbook:
Eachhourbeginswithanoverviewofwhatyouwilllearn.
Step-by-stepinstructionsareprecededbyaToDoicon.
Everyhourendswithasummaryandaseriesofcommonlyaskedquestions
andanswers;hopefully,you'llfindtheanswerstoyourquestionsamong
them.
Inaddition,theseelementsappearthroughoutthebook:
BytheWay
Notesprovideyouwithcommentsandasidesaboutthetopicathand.
DidyouKnow?
Tipsoffershortcutsandhintsongettingthetaskdone.
WatchOut!
Cautionsexplainroadblocksyoumightencounterwhenyouwork
withPerlandtellyouhowtoavoidthem.
Newtermsareemphasizedbybeingplacedinboldforyoureasyreference.
PartI:PerlFundamentals
HOUR1GettingStartedwithPerl
HOUR2Perl'sBuildingBlocks:NumbersandStrings
HOUR3ControllingtheProgram'sFlow
HOUR4StackingBuildingBlocks:ListsandArrays
HOUR5WorkingwithFiles
HOUR6PatternMatching
HOUR7Hashes
HOUR8Functions
Hour1.GettingStartedwithPerl
WhatYou'llLearninThisHour
InstallingPerl
AccessingPerl'sinternaldocumentation
WritingyourfirstPerlscript
Perlisageneral-purposeprogramminglanguage.Itcanbeusedforanythingthat
anyotherprogramminglanguagecanbeusedfor.Ithasbeenusedinevery
industryimaginableforalmostanytaskyoucanthinkof.It'susedonthestock
market;inmanufacturing,design,bioinformatics,customersupport,quality
control,systemsprogramming,payroll,andinventory;and,ofcourse,onthe
Web.
PerlisusedinsomanyplacesbecausePerlisagluelanguage.Agluelanguage
isusedtobindthingstogether.Youprobablywouldn'twanttowriteaword
processorinPerlalthoughyoucouldbecausegoodwordprocessorsarealready
available.Writingadatabase,aspreadsheet,anoperatingsystem,orafullfeaturedWebserverinPerlwouldbesillybutagain,possible.
WhatPerlisgoodatistyingtheseelementstogether.Perlcantakeyour
database,convertitintoaspreadsheet-readyfile,and,duringtheprocessing,fix
thedataifyouwant.Perlcanalsotakeyourwordprocessingdocumentsand
convertthemtoHTMLfordisplayontheWeb.
Asasideeffectofbeingalanguagedesignedtoglueelementstogether,Perlis
veryadaptable.Itrunsunder,atlastcount,abouttwodozenoperating
systemsandprobablymore.Perl'sprogrammingstyleisveryflexible,soyoucan
dothesamethingsinmanyways.YourPerlprogramsmaylooknothinglike
mine,butiftheybothwork,that'sokay.Perlcanbeastrictlanguagewhenit
needstobe,butitcanalsobeforgivingtonewsprogrammersifyouwant.It'sall
uptoyou.
Letmejustclearupafewpoints.Thenameoftheprogramminglanguageis
Perl.Thenameoftheprogramthatrunsyourprograms,theinterpreter,isperl.
Thedistinctionusuallyisn'tveryimportanttoyouexceptwhenyou'retryingto
startyourprograms;thenit'salwaysperl.Sometimesbutnothereyouwillsee
PerlwrittenasPERL,probablybecauseoneexplanationofPerl'snameisasan
acronymforPracticalExtractionandReportLanguage.Nobodyeverreally
calleditPERL;it'stoopretentious.It'sjustPerltoitsfriends.
BytheWay
ManyofPerl'sfeatureswere"borrowed"fromotherlanguages.This
borrowinggaverise,earlyon,toPerl'sotheracronym-expansion:
PathologicallyEclecticRubbishLister.
InstallingPerl
ToplaywithPerl,youfirsthavetoinstallit.Perl'sinstallationisdesignedtobe
easyanderrorfree.Infact,aspartoftheinstallationsteps,Perlshoulddoaselftesttomakesurethatit'sokay.Theinstallationproceduresvarywidely
dependingonwhatoperatingsystemyouhave.So,togetthingsmoving,pick
whichoperatingsystemyouhavefromthesectionshere,andfollowalong.
Stop!Wait!MaybeYouAlreadyHavePerl
BeforeyougothroughallthetroubletoinstallPerlonyoursystem,youshould
checktoseewhetheryoualreadyhaveit.SomeUnixvendorsshipPerlwiththe
operatingsystem.WindowsNTcomeswithPerlaspartoftheWindowsNT
ResourceKit(butthatversionisabitold).ToseewhetheryouhavePerl
properlyinstalledonyouroperatingsystem,youneedtogettoacommand
prompt.
UnderUnix,simplylogintothesystem.Ifyouhaveagraphicalenvironment,
youneedtoopenaterminalwindow.Afteryou'veloggedinoropenedyour
window,youmayseeapromptlikethis:
$
Itmightbea%oritmightlooklikebash%,buteitherway,itiscalledtheshell
promptorcommandprompt.Forthefirstfewhours,you'llneedtobeatthis
prompttointeractwithPerl.
ToseewhetherPerlisproperlyinstalledonyoursystem,typethefollowing(but
notthe$prompt):
$perl-v
Eitherthesystemrespondswithanerrormessagesuchascommandnot
found,orPerlrespondsandprintsitsversionnumber.IfPerlprintsitsversion
number,it'sinstalled.Youprobablydonothavetoreinstallit.
WatchOut!
Theversionnumberreportedshouldbeatleast5perhaps5.004,
5.005,5.6,5.8,andsoonbutnolower.IfPerlrespondswithaversion
of4.x,youmustinstallanewcopy.Perlversion4isold,buggy,and
nolongermaintained;fewoftheexamplesinthisbookwillwork
withPerlversion4.Atthetimeofthiswriting,5.8.6isconsideredthe
currentversionofPerl.
ToseewhetherPerlisproperlyinstalledonaWindowsmachineyouneedtoget
toanMS-DOSprompt,similartoFigure1.1.
Figure1.1.YoucancheckyourversionofPerlatthisDOSprompt.
[Viewfullsizeimage]
Atthatprompt,typethefollowing(butdon'trepeattheprompt):
C:\>perl-v
IfPerlisproperlyinstalled,itanswerswithitsversionnumber.Asnotedinthe
previouscaution,itshouldbeatleastversion5.IfMS-DOSreplieswithBad
commandorfilename,youneedtoinstallPerlproperly.
OntheMacintosh(runningMacOS),youcanchecktoseewhetherPerlis
installedbyrunningFileFind(Command-f)for'MacPerl'asshowninFigure
1.2.Iftheapplicationisfound,openitandlookatthe"AboutMacPerl"option
undertheApplemenu.YoushouldhaveatleastVersion5.2.0Patchlevel5.004;
otherwise,youshouldinstallanewversionofMacPerl.
Figure1.2.LookingforPerlontheMacintosh.
NewerMacintoshsystemsrunMacOSX.Underneaththepoint-and-click
interface,thereisaUnixoperatingsystem.Togetashellprompt(sothatyoucan
followtheUnixinstructions)gotoFinder,Applications,Utilitiesandselect
Terminal.YoushouldseeawindowsimilartoFigure1.3.
Figure1.3.MacOSXTerminal,withPerlversionoutput.
GenerallyforMacOSX,followtheUnixinstructionsinthisbook.Thereare
extensionsparticulartoMacOSXthatyoucandownloadfromCPAN.
