Programming visual c++ NET core reference 6th ed 2003

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Shepherd,George
ProgrammingwithMicrosoftVisualC++.NET,SixthEdition(CoreReference)
p.cm.
Includesindex.
ISBN0-7356-1549-7
2002

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AcquisitionsEditors:JulianaAldousandDanielleBird
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DedicatedtoSandyDastonandTedShepherd


Acknowledgments
Thispartofbookwritingisalwaysthebest—everybodyinvolvedisnearlydone
withthemanuscriptandallthat'slefttodoistothankeverybody.Becausethe
author'snameappearsonthecover,it'ssometimeseasytoforgetalltheother
folksinvolvedinaprojectaslargeasthis.Manyotherfolksgavetheirtimeand
energytothisproject,andIwishtothankyou.
ThankyouSandyDastonandTedShepherd—myfamily,foryoursupportwhile
Iwrotethisbook.
Thankyou,DeniseBankaitis.Astheprojecteditor,youkeptmegoingby

remindingmeoftheimportanceofthisproject(akeyC++referencefor.NET)
andbycoordinatingtheeffortsoftherestoftheteam,whichincludesJulieXiao,
InaChang,DanielleBird,JulianaAldous,JoelPanchot,CarlDiltz,andGina
Cassill.
Thankyou,JulieXiao,forkeepingthemanuscriptaccurate.
Thankyou,InaChang,formakingmysentencesreadable.
Thankyou,DanielleBirdandJulianaAldous.Asacquisitioneditors,yougot
thisprojectrollingandkeptitontrack.
Thankyou,JoelPanchot,formakingsuretheartinthisbooklooksgood.
Thankyou,CarlDiltzandGinaCassill,forcomposingthemanuscriptand
makingitlookgreat.
IwouldalsoliketothankthefolksatDevelopMentor,forprovidingawonderful
environmentandcommunityforthinkingandlearningaboutmoderncomputing.
Youguysarewonderful.


Introduction
ThereleaseoftheMicrosoftVisualStudio.NET(andVisualC++.NETin
particular)hasunderscoredMicrosoft’sincreasingfocusonInternet
technologies,whichareattheheartoftheMicrosoft.NETarchitecture.In
additiontosupportingthe.NETinitiative,VisualC++.NETkeepsallthe
productivity-boostingfeaturesyou’refamiliarwith,suchasEditAndContinue,
IntelliSense,AutoComplete,andcodetips.VisualC++.NETalsoincludesmany
newfeaturessuchasmanagedcodeextensionsfor.NETprogramming,support
forattributedcode,andamoreconsistentdevelopmentenvironment.These
featurestakeVisualC++.NETtoanewlevel.Thisbookwillgetyouupto
speedonthelatesttechnologiesintroducedintoVisualC++.


.NET,MFC,andATL

Thetechnologychurnwefacethesedaysisprettyimpressive.Wewentfromno
computersonourofficedesktopstonearlyeveryonehavingacomputerrunning
MS-DOSinthe1980stonearlyeveryonerunningMicrosoftWindowsbythe
mid-1990s.Thetechnologywheelisabouttoturnagain.Inthelate1990s,
everyonewasdevelopingWebsitesbyhandusingtoolssuchasrawHypertext
MarkupLanguage(HTML),CommonGatewayInterface(CGI),InternetServer
ApplicationProgrammingInterface(ISAPI)DLLs,Java,andActiveServer
Pages(ASP).InJuly2000,Microsoftannouncedtotheworldthatitwould
changeallthatbybettingthecompanyonanewtechnologydirectionnamed
.NET.
ThecurrentthrustofMicrosoftisindeed.NET.Foranumberofyears,it’sbeen
possibletobuildaWebsitebysettingupaserversomewhere,gettinganIP
address,andputtingupsomecontent.AnyonewiththeURLofyoursitecansurf
thereandcheckitout.Commercialenterpriseshavebeentakingadvantageof
theWebbypostinginformationthat’susefultocustomers.TheWebhasalso
becomeaninvaluableresearchtoolandefficientnewsbroadcastmedium.
ThecomputingworldofthenearfuturewillinvolvetheWebheavily.However,
ratherthanjusthavinghumaneyeballslookatWebsites,computersthemselves
willlookatWebsites.Thatis,WebsiteswillbeprogrammablethroughWeb
services.The.NETvisionalsopushestheresponsibilityofprovidingarichuser
interfaceouttotheserver.
WithsomuchemphasisonWebservicesandserver-baseduserinterfaces,it
mightseemthatstandaloneapplicationsandclient-sideuserinterfacescenarios
—normallytherealmoftoolssuchastheMicrosoftFoundationClassLibrary
(MFC)—willbeleftinthedust.Buttheneedforrichclient-sideuserinterfaces
isunlikelytogoaway.ManythoughtthattheadventofthePCanddistribution
technologieswouldspelltheendofcentralizedprocessingonmainframesand
minicomputers.ItturnsoutthatPCsanddistributiontechnologiesonlyaddedto
theavailablecomputingarsenal.The.NETvisionofWebservicesandrichuser
interfacesprovidedbytheserveronlyaddstotheoptionsavailabletosoftware

developers.Richclient-sideuserinterfaceswillcontinuetobeviableformany
typesofapplications,runningalongsideotherapplicationsthatuseotherkindsof
userinterfaces(suchasserver-generateduserinterfaces).


MFCisamatureandwell-understoodtechnologythat’saccompaniedbyahost
ofthird-partyextensions.Foratleastalittlewhilelonger,MFCrepresentsthe
mosteffectivewaytowritefull-featuredstandaloneapplications.Agoodportion
ofthisbookwillfocusonMFC-styledevelopment,butwe’llalsocover
WindowsForms—the.NETwaytowriteclient-sideuserinterfaces.
Ofcourse,thenextquestionis:WheredoesthisleaveCOM?COMhassolved
manyproblemsrelatedtodistributedprocessing,butithassomeserious
shortcomings—mostlycenteredaroundcomponentversioningandtype
information.Microsoft’s.NETvisionisbasedonthecommonlanguageruntime.
TheruntimetakestheplaceofCOMastheinteroperabilitystandardwithin
.NET.We’llcover.NETandthecommonlanguageruntimeindepthinPartVI
ofthisbook.
COMandthecommonlanguageruntimerepresentdifferentapproachesto
componentarchitecture,butMicrosofthastakengreatcaretoensureaseamless
coexistence.TheinteroperabilitypathbetweenCOMandtheruntimeissmooth
inmostcases.Withinthe.NETworld,youprobablywon’tfindyourselfusing
COMasacomponentarchitecture.However,youmightfindyourselfusing
ActiveTemplateLibrary(ATL)Server,whichisahigh-performancemeansof
writingWebsites.
I’veupdatedthecoverageofATLandMFCinthiseditionofthebookbecause
you’llstillfinditveryuseful.Moreimportant,I’llshowyouhowtoleverage
yourheritagecode(soundsbetterthan“legacycode,”doesn’tit?)asyoumove
intothe.NETworld.

ManagedC++vs.C#
The.NETplatformhasintroducedanewC++-likelanguagenamedC#.C#isa
curly-brace-orientedlanguagewithoutalltheheadachesofC++.MuchofC#’s
appealisduetothefactthatit’smissingsomeofthemoreproblematicelements
ofC++(suchasrawpointermanagement)whilemaintainingtheusefulfeatures
(suchasvirtualfunctions).TheC#compilereventuallyemitsmanagedcode—
thekindthatrunsunderthecommonlanguageruntime.
However,theentireworldisn’tgoingtoswitchovertoC#overnight.There’s
justtoomuchC++codeouttheretoconvert.Also,itwilltakeabitoftimefor
developerstobecomefullycomfortablewithC#.Inthemeantime,.NEThas
introducedextensionstoC++forproducingmanagedcode(codethatrunsunder
thecommonlanguageruntime).ManagedExtensionsforC++willhelpeasethe
burdenofdevelopingsoftwareforthe.NETplatformbecausetheyallowyouto
quicklyupdateexistingC++codetoworkwith.NET.Gettingthemanagedcode
featuresinC++meanssprinklingyourcodewithvariouskeywords.Intheend,
C#andmanagedC++boildowntothesameexecutablecodeoncethecompilers
aredonewithit.Inthe.NETworld,you’llprobablyfindyourselfwritingnew
componentsusingC#whileusingmanagedC++toadd.NETfeaturestoyour
existingcodebase.


.NETvs.theJavaPlatform
Inrecentyears,we’veseenagreatdealofinterestintheJavaprogramming
languageandplatform.JavabecameagreatboonforInternetdevelopersby
providingausefulmeansofdistributingclientuserinterfaces(throughJava
applets)andbyprovidingenterprisesolutionsthroughJavaEnterpriseEdition.
Now,.NEThasbecomethebestInternetdevelopmentplatformavailabletoday.
UnliketheJavaplatform,whichrequiresthatyouwriteallyourcodeusingthe
Javasyntax,.NEToftenletsyouusemultiplesyntaxestoarriveatthesame
machineinstructionset.YoucanuseC++(themainfocusofthisbook)andits

managedextensions,VisualBasic.NET,C#,andevenahostofthird-party.NET
languagestowriteyourprograms.Onceyoudevelopyoursourcecode,itis
compiledtointermediatelanguageandtheneventuallymachinecodebeforeit
runs.Because.NETcodeismanagedbyaruntime,yougetbenefitssuchas
garbagecollectionandbettercodesecurity.


WhoThisBookIsFor
VisualC++.NET,withitssophisticatedapplicationframeworkandsupportfor
.NET,isforprofessionalprogrammers,andsoisthisbook.I’llassumethat
you’reproficientintheClanguage—youcanwriteanifstatementwithout
consultingthemanual.AndI’llassumethatyou’vebeenexposedtotheC++
language—you’veatleasttakenacourseorreadabookevenifyouhaven’t
writtenmuchcode.YoumightcomparelearningC++tolearningFrench.You
canstudyFrenchinschool,butyouwon’tbeabletospeakfluentlyunlessyou
gotoaFrench-speakingcountryandstarttalkingtopeople.
TheVisualC++wizardssaveyoutimeandimproveaccuracy,butprogrammers
mustunderstandthecodethatthewizardsgenerateand,ultimately,theymust
understandthestructureoftheMFCandATLlibraries,theinnerworkingsofthe
Windowsoperatingsystem,andhow.NETworks.Iwon’tassume,however,that
youalreadyknowWindowsand.NETprogramming.I’msurethatproficientC
programmerscanlearnWindowstheMFCwayandthe.NETway.It’smore
importanttoknowC++thanitistoknowtheWin32applicationprogramming
interface(API).Youshould,however,knowhowtorunWindowsandWindowsbasedapplications.
Ifyou’realreadyexperiencedwiththeWin32APIorwiththeMFClibrary,
there’ssomethinginthisbookforyou,too.You’lllearnaboutnewfeaturessuch
astheMultipleTop-LevelInterface(MTI)andtheVisualC++.NETwizards.If
youhaven’talreadyfiguredouttheComponentObjectModel(COM),thisbook
presentssomeimportanttheorythatwillgetyoustartedonunderstanding
ActiveXcontrols.You’llalsolearnaboutATLServerandOLEDBtemplates.

Andyou’lllearnaboutC++programmingfortheInternet(includingDynamic
HTML).Finally,thisbookincludeshard-to-findcoverageofthenewmanaged
C++extensions.


What’sNotCovered
It’simpossibletocovereveryaspectofWindowsand.NETprogrammingina
singlebook.I’veexcludedtopicsthatdependonspecial-purposehardwareand
software,suchasMAPI,TAPI,andcommunicationsportaccess.I’llcoverusing
ActiveXcontrolsinanapplicationandwritingActiveXcontrolsusingATL,but
I’lldeferthein-depthcoveragetoAdamDenningandhisActiveXControls
InsideOut(MicrosoftPress,1997).I’llgetyoustartedwith32-bitmemory
management,DLLtheory,multi-threadedprogrammingtechniques,and.NET
programming,butyouneedtogetthethirdeditionofJeffreyRichter’s
ProgrammingApplicationsforMicrosoftWindows(MicrosoftPress,1997)if
you’reseriousaboutthesesubjects.AnotherusefulbookisMFCInternalsby
GeorgeShepherdandScotWingo(Addison-Wesley,1996).I’llalsogiveyoua
headstartintothe.NETspace,butI’llleavethehardcoreruntimeissuesto
JeffreyRichter’sApplied.NETProgramming(MicrosoftPress,2002).


HowtoUseThisBook
Whenyou’restartingwithVisualC++.NET,youcanusethisbookasatutorial
bygoingthroughitsequentially.Later,youcanuseitasareferencebylooking
uptopicsinthetableofcontentsorintheindex.Becauseofthetight
interrelationshipsamongmanyapplicationframeworkelements,itwasn’t
possibletocleanlyisolateeachconceptinitsownchapter,sothebookisn’t
organizedasanencyclopedia.Whenyouusethisbook,you’lldefinitelywantto
keeptheonlinehelpavailableforlookingupclassesandmemberfunctions.
Ifyou’reexperiencedwithearlierversionsofVisualC++,scanPartIforan

overviewofnewfeatures.ThenskipthebasicMFCcoverageinPartIIbutread
themoreadvancedcoverage.Also,besuretoreadthe.NETcoverage.Muchof
thesoftwaredevelopmentcommunity’seffortsareheadinginthisdirection,and
VisualC++.NETfullysupportsthe.NETprogrammingmodel.


HowThisBookIsOrganized
Asthetableofcontentsshows,thisbookhassixpartsandanappendixsection.

PartI:Windows,VisualC++.NET,andApplication
FrameworkFundamentals
Thisparttriestostrikeabalancebetweenabstracttheoryandpractical
application.AfteraquickreviewofWin32andtheVisualC++.NET
components,you’llbeintroducedtotheMFCapplicationframeworkandthe
document-viewarchitecture.You’lllookatasimple“Hello,world!”program
builtwiththeMFClibraryclassesthatrequiresonly30linesofcode.

PartII:MFCEssentials
TheMFClibrarydocumentationpresentsalltheapplicationframeworkelements
inquicksuccession,withtheassumptionthatyou’reatleastfamiliarwiththe
originalWindowsAPI.InPartIIofthisbook,you’reconfinedtoonemajor
applicationframeworkcomponent—theview,whichisreallyawindow.You’ll
learnwhatexperiencedWindowsprogrammersknowalready,butinthecontext
ofC++andtheMFClibraryclasses.You’llusetheVisualC++.NETtoolsthat
eliminatemuchofthecodingdrudgerythatearlyWindowsprogrammershadto
endure.
Thispartcoversalotofterritory,includinggraphicsprogrammingwithbitmaps,
dialogdataexchange,ActiveXcontrolusage,32-bitmemorymanagement,and
multi-threadedprogramming.Theexerciseswillhelpyoutowritereasonably
sophisticatedWindows-basedprograms,butthoseprogramswon’ttake

advantageoftheadvancedapplicationframeworkfeatures.

PartIII:MFC’sDocument-ViewArchitecture
Thispartintroducestherealcoreofapplicationframeworkprogramming—the
document-viewarchitecture.You’lllearnwhatadocumentis(somethingmuch
moregeneralthanawordprocessingdocument),andyou’llseehowtoconnect
thedocumenttotheviewthatyoustudiedinPartII.You’llbeamazed,once
you’vewrittenadocumentclass,athowtheMFClibrarysimplifiesfileI/Oand


printing.
Alongtheway,you’lllearnaboutcommandmessageprocessing,toolbarsand
statusbars,splitterframes,andcontext-sensitivehelp.You’llalsobeintroduced
totheSingleDocumentInterface(SDI),theMultipleDocumentInterface
(MDI),andtheMultipleTop-LevelInterface(MTI),whichisthecurrent
standardforWindows-basedapplicationssuchasMicrosoftWord.
PartIIIalsodiscussesdynamiclinklibraries(DLLs)writtenwiththeMFC
library.You’lllearnthedistinctionbetweenanextensionDLLandaregular
DLL.

PartIV:COM,Automation,ActiveX,andOLE
COMitselfdeservesmorethanonebook.PartIVwillgetyoustartedinlearning
fundamentalCOMtheoryfromtheMFCpointofview.You’llprogressto
Automation,whichisthelinkbetweenC++andVisualBasicforApplications
(VBA).You’llalsobecomefamiliarwithuniformdatatransfer,andyou’lllearn
thebasicsofcompounddocumentsandembeddedobjects.You’lllearnaboutthe
ATLclasslibrarysupportforOLEDB.

PartV:ProgrammingfortheInternet
ThispartstartswithatechnicalInternettutorialthatcoverstheTCP/IPprotocol

andthefundamentalsofInternetprogramming.You’lllearnhowtodevelop
serversusingATLServer,andyou’lllearnhowtoprogramforDynamicHTML.

PartVI:.NETandBeyond
TheInternetisevolvingasthenextfrontierforsoftwaredevelopment.The
InternetisnolongerjustaboutbuildingWebsitesforpeopletosimplylookat—
it’saboutWebsitesthatpeoplecanprogram.Thewire’sinplace,butuntilthe
adventofXML,noonewasbeenabletoagreeonhowtosendmethodcalls
acrosstheInternet.Twomainthrustsof.NETincludeWebservicesandserverbaseduserinterfaces..NETfullysupportsboththesenotions,alongwithanew
waytowriteclientuserinterfaces:WindowsForms.PartVIcoverswhat.NETis
allaboutandwhatyoucandowithitasaplatform.Includedherearechapters
onthecommonlanguageruntimeandmanagedcode,programmingmanaged


componentsusingC++,ASP.NET,andADO.NET.

Appendixes
AppendixAcontainsalistofmessagemapmacrosandtheircorresponding
handlerfunctionprototypes.ThecodewizardsavailablefromClassView
usuallygeneratethiscodeforyou,butsometimesyoumustmakemanual
entries.
AppendixBoffersadescriptionoftheMFCapplicationframework’sruntime
classinformationanddynamiccreationsystem.Thisisindependentofthe
runtimetypeinformation(RTTI)featurethatisnowapartofANSIC++.


Win32vs.Win16
AfewoldcomputersouttherearestillrunningWindows3.1.However,there’s
notmuchpointinspendingmoneywritingnewprogramsforobsolete
technology.ThiseditionofProgrammingwithMicrosoftVisualC++.NETis

about32-bitprogrammingforWindows98/MeandWindowsNT/2000/XPusing
theWin32API.Ifyoureallyneedtodo16-bitprogramming,Isuggestthatyou
findanoldcopyofthesecondeditionofthisbook.


SystemRequirements
Tousethisbook,you’llneedtohaveVisualC++.NETorVisualStudio.NET
installedonyourcomputer.Anycomputerthatsatisfiestheminimum
requirementsforVisualC++.NETwillworkeffectivelywithmostofthe
examplesinthisbook.BeawarethatWindowsXPHomeEditionandWindows
NT4.0don’tsupportthehostingofASP.NETWebapplicationswiththe.NET
Framework.Youcanbuildtheseprojectsontheseoperatingsystems,butyou’ll
needtouploadtheprojectstoaproperlyconfiguredhosttoexecutethem.


SampleFiles
Youcanfindthesamplefilesonthebook’scompanionCD,alongwithother
supplementalcontent.ToaccessthefilesontheCD,insertthediscinyour
computer’sCDdriveandmakeaselectionfromthemenuthatappears.Ifthe
AutoRunfeatureisnotenabledonyoursystem(ifamenudoesn’tappearwhen
youinserttheCDintothedrive),runStartCD.exeintherootfolderofthe
companionCD.Installingthesamplefilesonyourharddiskrequires
approximately60MBofdiskspace.Ifyouhavetroublerunninganyofthese
files,refertothetextinthebookthatdescribestheseprograms.
WithaconventionalC-languageprogramusingtheWindowsAPI,thesource
codefilestellthewholestory.WiththeMFClibraryapplicationframework,
thingsarenotsosimple.TheMFCApplicationWizardgeneratesmuchofthe
C++code,andtheresourcesoriginateintheresourceeditors.Theexamplesin
theearlychaptersofthisbookincludestep-by-stepinstructionsforusingthe
toolstogenerateandcustomizethesourcecodefiles.You’dbewelladvisedto

walkthroughthoseinstructionsforthefirstfewexamples—there’sverylittle
codetotype.Forthemiddlechapters,usethecodefromthesamplefilesbut
readthroughthestepstoappreciatetheroleoftheresourceeditorsandthe
wizards.Forthefinalchapters,notallthesourcecodeislisted.You’llneedto
examinethesamplefilesforthoseexamples.
Asidefromthesamplefiles,thebook’ssupplementalcontentincludestwo
eBookinstallations:astandaloneeBookinstallationandaVisualStudioHelp
eBookinstallation.ThestandaloneeBookinstallationallowsyoutoaccessan
electronicversionoftheprintbookdirectlyfromyourdesktop.TheVisual
StudioHelpeBookinstallationallowsyoutoaccessthesecondelectronic
versionoftheprintbookdirectlyfromtheVisualStudio.NEThelpsystem.


VisualStudio.NETProfessionalTrialVersion
InadditiontothecompanionCD,thisbookalsoincludesaDVDwithan
evaluationcopyofVisualStudio.NETProfessional.Thisevaluationcopycan
helpyoufollowtheexamplesinthisbookandgetyoustartedlearningVisual
C++.NET,butthesoftwarewillexpireandstopworking60daysafteryou
installit.Youcanlearnmoreaboutthisevaluationcopyanditssystem
requirementsatNote
thatnoproductsupportisavailableforthetrialversion.

WindowsFormsLibraryExtensions
OneofthebiggestsellingpointsbehindMFCduringthe1990swasthegreat
classlibrariesavailableforextendingtheframework.WithWindowsFormson
thehorizon,it’stimetokeepaneyeoutforclasslibrariesthatextendWindows
Forms.
MFCanditsextensionswereconfinedtotheC++language,butthe.NET
commonlanguageruntimeoffersavarietyofsyntaxesforwritingWindows
Forms,includingC#,VisualBasic.NET,andManagedC++.Syncfusion,a

companybasedinCary,NorthCarolina,providesawidevarietyof.NETtoolsto
makeprogrammingfor.NETeasier.Syncfusion’sEssentialSuiteincludes
componentstomakeyour.NETWindowsFormsapplicationsmoresolidand
polished.Youcandownloadafullyfunctional15-daytrialversionfrom
,aswellastheEssentialSuiteInteractiveShowcase,
anapplicationthatshowsseveralSyncfusioncomponentsinaction.The
componentsrununderthecommonlanguageruntime,sotheyworkwith
ManagedC++aswellaswithC#andVisualBasic.NET.


MicrosoftPressSupportInformation
Everyefforthasbeenmadetoensuretheaccuracyofthisbookandthecontents
ofthecompanionCD.MicrosoftPressprovidescorrectionsforbooksat
/>ToconnectdirectlytotheMicrosoftPressKnowledgeBaseandsubmitaquery,
goto: />Ifyouhavecomments,questions,orideasregardingthisbookorthecompanion
contentorquestionsthatarenotansweredbyqueryingtheKnowledgeBase,
pleasesendthemtoMicrosoftPressusingpostalmailore-mail:
MicrosoftPress
Attn:ProgrammingwithMicrosoftVisualC++.NETEditor
OneMicrosoftWay
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Notethatproductsupportisnotofferedthroughtheabovemailaddresses.For
MicrosoftVisualC++.NETsupportinformation,pleasevisittheMicrosoft
SupportWebsiteat:.


Chapter1
WindowsandVisualC++.NET
Intheearlynineties,thebattlewasforthedesktopoperatingsystem.Nowthat

battleisover,andMicrosoftWindowsrunsonthevastmajorityofpersonal
computersystems.Thischaptersummarizesthelow-levelWindows
programmingmodel(Win32,inparticular)andshowsyouhowtheMicrosoft
VisualC++.NETcomponentsworktogethertohelpyouwriteapplicationsfor
Windows.Alongtheway,youmightlearnsomenewthingsaboutWindowsas
well.


TheWindowsProgrammingModel
Nomatterwhichdevelopmenttoolsyouuse,programmingforWindowsis
differentfromold-stylebatch-orientedortransaction-orientedprogramming.To
getstarted,youneedtoknowsomeWindowsfundamentals.Asaframeof
reference,we’llusethewell-knownMS-DOSprogrammingmodel.Evenifyou
don’tcurrentlyprogramforplainMS-DOS,you’reprobablyfamiliarwithit.

MessageProcessing
WhenyouwriteanMS-DOS–basedapplicationinC,theonlyabsolute
requirementisafunctionnamedmain.Theoperatingsystemcallsmainwhen
theuserrunstheprogram,andfromthatpointon,youcanuseanyprogramming
structureyouwant.Ifyourprogramneedstogetuserkeystrokesorotherwise
useoperatingsystemservices,itcallsanappropriatefunction,suchasgetchar,
orperhapsusesacharacter-basedwindowinglibrary.
WhentheWindowsoperatingsystemlaunchesaprogram,itcallstheprogram’s
WinMainfunction.SomewhereyourapplicationmusthaveWinMain,which
performssomespecifictasks.Itsmostimportanttaskiscreatingtheapplication’s
mainwindow,whichmusthaveitsowncodetoprocessmessagesthatWindows
sendsit.AnessentialdifferencebetweenaprogramwrittenforMS-DOSanda
programwrittenforWindowsisthatanMS-DOS–basedprogramcallsthe
operatingsystemtogetuserinputbutaWindows-basedprogramprocessesuser
inputviamessagesfromtheoperatingsystem.

NOTEManydevelopmentenvironmentsforWindows,including
VisualC++.NETwithMicrosoftFoundationClass(MFC)library
version7.0,simplifyprogrammingbyhidingtheWinMainfunctionand
structuringthemessage-handlingprocess.WhenyouusetheMFC
library,youneednotwriteaWinMainfunction,butitisessentialthat
youunderstandthelinkbetweentheoperatingsystemandyour
programs.
MostmessagesinWindowsarestrictlydefinedandapplytoallprograms.For
example,aWM_CREATEmessageissentwhenawindowisbeingcreated,a


WM_LBUTTONDOWNmessageissentwhentheuserpressestheleftmouse
button,aWM_CHARmessageissentwhentheusertypesacharacter,anda
WM_CLOSEmessageissentwhentheuserclosesawindow.Allmessageshave
two32-bitparametersthatconveyinformationsuchascursorcoordinates,key
code,andsoforth.WindowssendsWM_COMMANDmessagestothe
appropriatewindowinresponsetousermenuchoices,dialogboxbuttonclicks,
andsoon.Commandmessageparametersvarydependingonthewindow’s
menulayout.Youcandefineyourownmessages,whichyourprogramcansend
toanywindowonthedesktop.Theseuser-definedmessagesactuallymakeC++
lookalittlelikeSmalltalk.
Don’tworryyetabouthowthesemessagesareconnectedtoyourcode.That’s
thejoboftheapplicationframework.Beaware,though,thattheWindows
messageprocessingrequirementimposesalotofstructureonyourprogram.
Don’ttrytoforceyourWindows-basedprogramstolooklikeyouroldMS-DOS
programs.Studytheexamplesinthisbook,andthenbepreparedtostartfresh.

TheWindowsGraphicsDeviceInterface
ManyMS-DOSprogramswritedirectlytothevideomemoryandtheprinter
port.Thedisadvantageofthistechniqueistheneedtosupplydriversoftwarefor

everyvideoboardandeveryprintermodel.Windowsintroducedalayerof
abstractioncalledtheGraphicsDeviceInterface(GDI).Windowsprovidesthe
videoandprinterdrivers,soyourprogramdoesn’tneedtoknowthetypeof
videoboardandprinterattachedtothesystem.Insteadofaddressingthe
hardware,yourprogramcallsGDIfunctionsthatreferenceadatastructurecalled
adevicecontext.Windowsmapsthedevicecontextstructuretoaphysicaldevice
andissuestheappropriateinput/outputinstructions.TheGDIisalmostasfastas
directvideoaccess,anditallowsdifferentapplicationswrittenforWindowsto
sharethedisplay.
Laterinthebook,we’lllookatGDI+.Asyoumightguess,GDI+isthe
successortoGDI.TheservicesofGDI+areexposedthroughasetofC++
classesdeployedasmanagedcode—thatis,coderunningunderthecommon
languageruntime.GDI+introducesseveralenhancementsoverclassicGDI,
includinggradientbrushes,cardinalsplines,independentpathobjects,scalable
regions,alphablending,andmultipleimageformats.


Resource-BasedProgramming
Tododata-drivenprogramminginMS-DOS,youmusteithercodethedataas
initializationconstantsorprovideseparatedatafilesforyourprogramtoread.
WhenyouprogramforWindows,youstoredatainaresourcefileusinga
numberofestablishedformats.Thelinkercombinesthisbinaryresourcefile
withtheC++compiler’soutputtogenerateanexecutableprogram.Resource
filescanincludebitmaps,icons,menudefinitions,dialogboxlayouts,and
strings.Theycanevenincludecustomresourceformatsthatyoudefine.
Youuseatexteditortoeditaprogram,butyougenerallyuseWYSIWYG(what
youseeiswhatyouget)toolstoeditresources.Ifyou’relayingoutadialogbox,
forexample,youselectelements(buttons,listboxes,andsoforth)fromanarray
oficonscalledacontrolpalette,andyoupositionandsizetheelementswiththe
mouse.VisualC++.NEThasgraphicsresourceeditorsforallstandardresource

formats.

MemoryManagement
WitheachnewversionofWindows,memorymanagementgetseasier.Ifyou’ve
heardhorrorstoriesaboutlockingmemoryhandles,thunks,andburgermasters,
don’tworry.That’sallinthepast.Todayyousimplyallocatethememoryyou
need,andWindowstakescareofthedetails.Chapter10describescurrent
memorymanagementtechniquesforWin32,includingvirtualmemoryand
memory-mappedfiles.

Dynamic-LinkLibraries
IntheMS-DOSenvironment,allofaprogram’sobjectmodulesarestatically
linkedduringthebuildprocess.Windowsallowsdynamiclinking,whichmeans
thatspeciallyconstructedlibrariescanbeloadedandlinkedatruntime.Multiple
applicationscansharedynamic-linklibraries(DLLs),whichsavesmemoryand
diskspace.Dynamiclinkingincreasesprogrammodularitybecauseyoucan
compileandtestDLLsseparately.
DesignersoriginallycreatedDLLsforusewiththeClanguage,andC++has
addedsomecomplications.TheMFClibrarydeveloperssucceededincombining
alltheapplicationframeworkclassesintoafewready-builtDLLs.Thismeans