Download pdf - FreeBASIC Manual - documentation.help · FreeBASIC is a free 32-bit compiler for the BASIC language. It is open source and licensed under the GPL. It is designed to be syntax compatible

FreeBASICManual

WelcometoFreeBASIC|GettingHelpwithFreeBASIC

LanguageDocumentation

Keywords-AlphabeticalKeywords-FunctionalGraphicsKeywordsOperatorsList

VariablesandDataTypesVariableDeclarationsUserDefinedTypesStandardDataTypesStandardDataTypeLimitsConvertingBetweenDataTypesOperatorsOperatorsOperatorPrecedenceBitwiseOperators&TruthTablesStatementsControlFlowProceduresModularizingOtherPreprocessorEscapeSequencesInStringLiteralsMeta-statementsIntrinsicDefinesErrorHandling

TutorialsProgrammer'sGuideCommunityTutorialsCommunityCodeLibraryExternalLibrariesIndex

UsingtheFreeBASICcompiler

InstallingFreeBASIC|RequirementsRunningFreeBASICUsingtheCommandLine|CommandLineOptions

DebuggingwithFreeBASIC

CompilerErrorMessagesToolsusedbyfbc

FreeBASICdialectsandQBASIC

FreeBASICandQbasic|DifferencesfromQBFreeBASICDialects

FAQs

CompilerFAQGraphicsLibraryFAQ

InlineAsm

RuntimeLibraryReference

ArrayFunctionsBitManipulationConsoleFunctionsDateandTimeFunctionsErrorHandlingFunctionsFileIOFunctionsMathematicalFunctionsMemoryFunctionsOperatingSystemFunctionsStringFunctionsThreadingSupportFunctionsUserInputFunctions

GraphicsLibraryReference

2DDrawingFunctionsUserInputFunctionsScreenFunctions

Supportedgraphicsdrivers(backends)KeyboardScanCodesDefaultPalettes

RuntimeLibraryFAQXboxportFAQDOSrelatedFAQWindowsrelatedFAQLinuxrelatedFAQ

Miscellaneous

ObsoleteKeywordsGlossaryMiscellaneousKeywordsCStandardLibraryFunctionsASCIICharacterCodesRuntimeErrorCodesC/C++vs.FreeBASICsyntaxcomparisonC/C++vs.FreeBASICintegerdatatypecomparison

HackingonFreeBASIC

Developer'sTableofContents

Thisdocumentlastcompiled:2016/01/3114:20:41fromhttp://www.freebasic.net/wiki/

WelcometoFreeBASIC

Welcometoourworld!Thispageisanoverviewofouronlinewarehouseofknowledge.Enjoyyoursurfingandwehopethiswillbethefirstofmanyvisits.

IntroductionFreeBASICisafree32-bitcompilerfortheBASIClanguage.ItisopensourceandlicensedundertheGPL.ItisdesignedtobesyntaxcompatiblewithQuickBASIC,whileexpandingonthelanguageandcapabilities.ItcancreateprogramsforMS-Windows,DOSandLinux,andisbeingportedtootherplatforms.SeeAboutFreeBASICandMainFeatures.

LatestVersionFreeBASICisabetareleasecompileranddevelopmentisongoing.Witheachfullupdate,manyfeaturesareadded,andbugsfrompreviousreleasesarefixed.Toseethelatestversionavailable,visithttp://sourceforge.net/projects/fbconSourceForge,orhttp://www.freebasic.net/index.php/downloadonFreeBASIC'sofficialwebsite.

RequirementsandInstallationMinimumhardwareislistedontheRequirementspage.VisitourInstallationpageforsettingupFreeBASIConyourcomputer.

RunningFreeBASICisacompilerandassuchisnotpackagedwithanIDE(IntegratedDevelopmentEditor),althoughthereareafewIDE'savailable.ForinformationonusingFreeBASICwithoutanIDE,seeRunning.

CompatibilitywithQuickBASICFreeBASICisdesignedtobesyntaxcompatiblewithQuickBASIC.Forbestcode-compatibilitywithQuickBASIC,theQBdialectcanbeusedwhencompilingsourcecode.SeeFreeBASICDialectsandDifferencesfromQB.

http://sourceforge.net/projects/fbchttp://sourceforge.nethttp://www.freebasic.net/index.php/downloadhttp://www.freebasic.net

DocumentationAllofficialdocumentationcanbefoundonlineinthewikiathttp://www.freebasic.net/wiki.Theonlinedocumentationisthemostup-to-dateresourceavailable.Inallcasesitcanberegardedasthecorrectversion.Thedownloadableversionsofthemanualaresnapshotsofthedocumentationavailableataparticulartimeandshouldbemostlycorrectforaspecificreleasedversionofthecompiler.However,wedonotmaintainmultipleversionsofthedocumentationsotheremaybesomediscrepancies.

StartingpointsintheManualTableofContentsGettingHelpwithFreeBASICProgrammer'sGuide

StartingpointsontheWebOfficialWebsiteathttp://www.freebasic.netOfficialForumsathttp://www.freebasic.net/forumOfficialArchiveathttp://www.freebasic.net/arch

ThankyouforusingFreeBASIC.Happycoding!

http://www.freebasic.nethttp://www.freebasic.net/forumhttp://www.freebasic.net/arch

GettinghelpwithFreeBASIC

ThereareseveraloptionsavailableforgettinghelpwithFreeBASIC.

TheManualThishugeuser'smanualisfullofinformationthatcanhelpyoulearntowriteprogramsusingFreeBASIC.

Themanualisavailableonlineathttp://www.freebasic.net/wiki.Thereisasearchboxatthebottomofeverypagetohelpyoufindwhatyou'relookingfor.

IfyouareunfamiliarwithFreeBASICorthedocumentation,youmayfindthesepagesagoodplacetostart:

TableofContentsProgrammer'sGuideLibraryHeadersIndexGlossaryCompilerFAQGraphicsLibraryFAQRuntimeLibraryFAQ

Adownloadablemanual(inCHMformat)isavailablefromthesourceforgeprojectpageathttp://sourceforge.net/projects/fbcwhichfeaturesafulltableofcontents,searchingcapabilities,anindex,plusallthesamecontentastheonlineversion.

SearchingthemanualonorofflineisanexcellentplacetostartfindinghelpabouthowtowriteanduseFreeBASICprograms.

ExamplesandSourceCodeInthe./examplesdirectorylocatedwhereFreeBASICwasinstalledonyoursystemarehundredsofexamplestobecompiledandrun.Mostoftheexternallibraryexampleswillneedadditionallibrariestobedownloadedtoallowthemtowork.SeeLibraryHeadersIndexforafulllist.

http://sourceforge.net/projects/fbc

FreeBASIC'sofficialcodearchiveislocatedathttp://www.freebasic.net/arch.Thisarchivehostsusercontributedlibrariesandtoolsandhaslinkstosourcecodelocatedonotherwebsites.

TutorialsCommunitycreatedtutorialsaboutFreeBASICcanbefoundatCommunityTutorials.Someselectedtutorialsareincludedinthismanual.

FreeBASICForumAnactivecommunityforumcanbefoundathttp://www.freebasic.net/forumwithseveralsub-forums.Theforumhasasearchfeaturethatcanhelpyoufindanswerstoquestionsorproblemsthatmayhavealreadybeenaskedandsolved.Firstdoasearchforyourproblem,ifyoucan'tfindtheanswerthenpostamessageinoneofthesub-forums.

ChatIRCorInternetRelayChatisagreatwaytochatwiththedevelopersandotherusers,someofwhomareveryknowledgeable.ThereareseveralwaystoconnecttoIRC,ifyouknowwhatyou'redoingsimplyjoin#freebasiconFreeNode.

Ifyouhaven'tthefoggiestwhatIRCisandyouhaveJavainstalled,youcansimplygohere.

Ifyou'retryingtogethelp,themostimportantthingistobepatient.Sometimesyouwon'tgetareplyrightaway.StickaroundorcheckbackandtheCommunitywilltryandassistyou.

http://www.freebasic.net/archhttp://www.freebasic.net/forumhttp://www.freebasic.net/index.php/chat

AlphabeticalKeywordsList

Alphabeticallistingofkeywords,macrosandprocedures.

Operators._#$ABCDEFGHIKLMNOPRSTUVWXYZ

OperatorsSeeOperatorList

....

___DATE____Date_Iso____Fb_64Bit____FB_ARGC____FB_ARGV____Fb_Arm____Fb_Asm____Fb_Backend____FB_BIGENDIAN____FB_BUILD_DATE____FB_CYGWIN____FB_DARWIN____FB_DEBUG____FB_DOS____FB_ERR____Fb_Fpmode____Fb_Fpu____FB_FREEBSD____Fb_Gcc____FB_LANG__

KKill

LLBoundLCaseLeftLenLetLibLineLineInputLineInput#LoByteLOCLocalLocateLockLOFLogLongLongIntLoopLoWordLposLPrint

__FB_LINUX____FB_MAIN____FB_MIN_VERSION____FB_MT____FB_NETBSD____FB_OPENBSD____FB_OPTION_BYVAL____FB_OPTION_DYNAMIC____FB_OPTION_ESCAPE____FB_OPTION_EXPLICIT____Fb_Option_Gosub____FB_OPTION_PRIVATE____FB_OUT_DLL____FB_OUT_EXE____FB_OUT_LIB____FB_OUT_OBJ____Fb_Pcos____FB_SIGNATURE____FB_SSE____Fb_Unix____Fb_Vectorize____FB_VER_MAJOR____FB_VER_MINOR____FB_VER_PATCH____FB_VERSION____FB_WIN32____FB_XBOX____FILE____FILE_NQ____FUNCTION____FUNCTION_NQ__

LSetLTrim

MMid(Statement)Mid(Function)MinuteMKDMkDirMKIMKLMKLongIntMKSMKShortModMonthMonthNameMultiKeyMutexCreateMutexDestroyMutexLockMutexUnlock

NNakedNameNamespaceNextNewNew(Placement)Next(Resume)NotNow

O

__LINE____PATH____TIME__

##Assert#define#else#elseif#endif#endmacro#error#if#ifdef#ifndef#inclib#include#lang#libpath#line#macro#pragma#print#undef

$$Dynamic$Include$Static$Lang

AAbsAbstract(Member)Access

ObjectOctOffsetOfOnErrorOn...GosubOn...GotoOnceOpenOpenComOpenConsOpenErrOpenLptOpenPipeOpenScrnOperatorOption()OptionBaseOptionByValOptionDynamicOptionEscapeOptionExplicitOptionGosubOptionNogosubOptionNoKeywordOptionPrivateOptionStaticOrOr(GraphicsPut)OrElseOutOutput

AcosAdd(GraphicsPut)AliasAllocateAlpha(GraphicsPut)AndAndAlsoAnd(GraphicsPut)AnyAppendAsAssertAssertWarnAscAsinAsmAtan2Atn

BBase(Initialization)Base(MemberAccess)BeepBinBinaryBitBitResetBitSetBLoadBooleanBSaveByref(Parameters)Byref(FunctionResults)

OverloadOverride

PPaintPalettepascalPCopyPeekPMapPointPointcoordPointerPokePosPreservePResetPrint?Print#?#PrintUsing?UsingPrivatePrivate:(AccessControl)ProcPtrPropertyProtected:(AccessControl)Pset(Statement)Pset(GraphicsPut)Ptr

ByteByVal

CCallCAllocateCaseCastCboolCByteCDblcdeclChainChDirChrCIntCircleClassClearCLngCLngIntCloseClsColorCommandCommonCondBroadcastCondCreateCondDestroyCondSignalCondWaitConstConst(Member)

PublicPublic:(AccessControl)Put(Graphics)Put#(FileI/O)

RRandomRandomizeReadRead(FileAccess)ReadWrite(FileAccess)ReallocateReDimRemResetRestoreResumeResumeNextReturnRGBRGBARightRmDirRndRSetRTrimRun

SSAddScopeScreen

Const(Qualifier)ConstructorConstructor(Module)ContinueCosCPtrCShortCSignCSngCsrLinCUByteCUIntCULngCULngIntCUnsgCurDirCUShortCustom(GraphicsPut)CVDCVICVLCVLongIntCVSCVShort

DDataDateDateAddDateDiffDatePartDateSerialDateValue

Screen(Console)ScreenCopyScreenControlScreenEventScreenInfoScreenGLProcScreenListScreenLockScreenPtrScreenResScreenSetScreenSyncScreenUnlockSecondSeek(Statement)Seek(Function)SelectCaseSetDateSetEnvironSetMouseSetTimeSgnSharedShellShlShrShortSinSingleSizeOfSleep

DayDeallocateDeclareDefByteDefDbldefinedDefIntDefLngDeflongintDefShortDefSngDefStrDefUByteDefUIntDefulongintDefUShortDeleteDestructorDestructor(Module)DimDirDoDo...LoopDoubleDrawDrawStringDyLibFreeDyLibLoadDyLibSymbol

EElse

SpaceSpcSqrStaticStatic(Member)stdcallStepStickStopStrStrigString(Function)StringStrPtrSubSub(Member)SwapSystem

TTabTanThenThisThreadcallThreadCreateThreaddetachThreadWaitTimeTimeSerialTimeValueTimerTo

ElseIfEncodingEnd(Block)End(Statement)EndIfEnumEnvironStatementEnvironEOFEqvEraseErfnErlErmnErrErrorEvent(MessageDataFromScreenevent)ExecExePathExitExpExportExtendsExternExtern...EndExtern

FFalseFieldFileAttrFileCopyFileDateTime

Trans(GraphicsPut)TrimTrueType(Alias)Type(Temporary)Type(Udt)TypeOf

UUBoundUByteUCaseUIntegerUlongULongIntUnionUnlockUnsignedUntilUShortUsing(Print)Using(Namespaces)

Vva_argva_firstva_nextValValLngValIntValUIntValULngVarVarPtr

FileExistsFileLenFixFlipForFor...NextFormatFracFreFreeFileFunctionFunction(Member)

GGet(Graphics)Get#(FileI/O)GetJoystickGetKeyGetMouseGoSubGoto

HHexHiByteHiWordHour

IIf...ThenIIfImageConvertRowImageCreateImageDestroyImageInfo

ViewPrintView(Graphics)Virtual(Member)

WWaitWBinWChrWeekdayWeekdayNameWendWhileWhile...WendWHexWidthWindowWindowTitleWInputWithWOctWriteWrite#Write(FileAccess)WSpaceWStrWstring(DataType)Wstring(Function)

XXorXor(GraphicsPut)

YYear

Z

ImpImplementsImportInkeyInpInput(Statement)Input(FileI/O)Input#Input$InStrInStrRevIntIntegerIs(SelectCase)Is(Run-TimeTypeInformationOperator)IsDateIsredirected

ZString

...(Ellipsis)

Usedinplaceofprocedureparametertopassavariablenumberofarguments,orastheupperboundinanarraydeclarationtodenotethatthenumberofelementswillbedeterminedbytheinitializer.

SyntaxDeclare{Sub|Function}proc_namecdecl(param_list,...){|

Dimarray_symbol([lboundTo]...)[Asdatatype]=>{expression_list

#defineidentifier([parameters,]variadic_parameter...)body

DescriptionTheellipsis(threedots,...)isusedinproceduredeclarationsanddefinitionstoindicateavariableargumentlist.Afirstargument(atleast)mustalwaysbespecifiedandtheproceduremustbecalledwiththeCcallingconventioncdecl.Intheprocedurebody,andva_nextareusedtohandlethevariablearguments.Onlynumerictypesandpointersaresupportedasvariablearguments(allbytesandshortspassedonvariableargumentsareimplicitlyconvertedtointegers,allsinglespassedonvariableargumentsareimplicitlyconvertedtodoubles).Stringscanbepassed,inwhichcaseaZStringPtrtothestringdataistaken.Avariadicprocedurenamecanneverbeoverloaded.

Usinganellipsisinplaceoftheupperboundinanarraydeclarationcausestheupperboundtobesetaccordingtothedatathatappearsintheexpression_list.Whentheellipsisisusedinthismanner,aninitializermustappear,andcannotbeAny.

Usinganellipsisbehindthelastparameterina#defineor#macrodeclarationallowstocreateavariadicmacro.Thismeansitispossibletopassanynumberofargumentstothevariadic_parameter,whichcanbeusedinthebodyasifitwasanormalmacroparameter.Thevariadic_parameterwillexpandtothefulllistofargumentspassedtoit,includingcommas,andcanalsobecompletelyempty.

Example

DeclareFunctionfoocdecl(xAsInteger,...)As

DimAsIntegermyarray(0To...)={0,1,2,3}PrintLBound(myarray),UBound(myarray)''0,3

''Usingavariadicmacrotowrapavariadicfunction#include"crt.bi"#defineeprintf(Format,args...)fprintf(stderr,Format,args)eprintf(!"Hellofromprintf:%i%s%i\n",5,"test"

''LISP-likeaccessorsallowingtomodifycomma-separatedlists#definecar(a,b...)a#definecdr(a,b...)b

DifferencesfromQB

NewtoFreeBASIC

Seealso

cdecl

va_arg

va_first

va_next

Dim

Static

#define

__DATE__

Intrinsicdefine(macrovalue)setbythecompiler

Syntax__DATE__

DescriptionSubstitutesthecompilerdateinaliteralstring("mm-dd-yyyy"format)whereused.

Example

Print"CompileDate:"&__DATE__

CompileDate:09-29-2011

DifferencesfromQB

NewtoFreeBASIC

Seealso

__Date_Iso__

__TIME__

Date

__Date_Iso__


Syntax__DATE_ISO__

DescriptionSubstitutesthecompilerdateinaliteralstring("yyyy-mm-dd"format)whereused.ThisformatisinlinewithISO8601andcanbeusedforlexicographicaldatecomparisons.

Example

Print"CompileDate:"&__DATE_ISO__

If__DATE_ISO__<"2011-12-25"ThenPrint"CompiledbeforeChristmasday2011"ElsePrint"CompiledafterChristmasday2011"EndIf

CompileDate:2011-09-29CompiledbeforeChristmasday2011

DifferencesfromQB

NewtoFreeBASIC

Seealso

__DATE__

__TIME__

Date

__Fb_64Bit__

Intrinsicdefinesetbythecompiler

Syntax__FB_64BIT__

DescriptionDefinecreatedatcompiletimeifthethecompilationtargetis64bit,otherwiseundefined.

Example

#ifdef__FB_64BIT__'...instructionsfor64bitOSes...#else'...instructionsforotherOSes#endif

DifferencesfromQB

NewtoFreeBASIC

Seealso

__FB_LINUX__

__FB_FREEBSD__

__FB_OPENBSD__

__FB_NETBSD__

__FB_CYGWIN__

__FB_DARWIN__

__Fb_Pcos__

CompilerOption:-target

__FB_ARGC__


Syntax__FB_ARGC__

DescriptionSubstitutedwiththenumberofargumentspassedinonthecommandline.

__FB_ARGC__isthenameofaparameterpassedtotheprogram'simplicitmainfunction,andthereforeisonlydefinedinthemodulelevelcodeofthemainmoduleforanapplication.

Example

DimiAsIntegerFori=0To__FB_ARGC__-1Print"arg";i;"='";Command(i);"'"Nexti

DifferencesfromQB

NewtoFreeBASIC

Seealso

__FB_ARGV__

Command

__FB_ARGV__


Syntax__FB_ARGV__

DescriptionSubstitutedwithapointertoalistofpointerstothezeroterminatedcommandlineargumentspassedinonthecommandline.

__FB_ARGV__isthenameofaparameterpassedtotheprogram'simplicitmainfunction,andthereforeisonlydefinedinthemodulelevelcodeofthemainmoduleforanapplication.

Example

DeclareFunctionmain_(_ByValargcAsInteger,_ByValargvAsZStringPtrPtr_)AsInteger

Endmain(__FB_ARGC__,__FB_ARGV__)

PrivateFunctionmain_(_ByValargcAsInteger,_ByValargvAsZStringPtrPtr_)AsInteger

DimiAsIntegerFori=0Toargc-1Print"arg";i;"='";*argv[i];"'"Nexti

Return0

EndFunction

DifferencesfromQB

NewtoFreeBASIC

Seealso

__FB_ARGC__

Command

__Fb_Arm__


Syntax__FB_ARM__

DescriptionDefinecreatedatcompiletimeifthecompilationtargetusestheARMCPUarchitecture,otherwiseundefined.

Example

#ifdef__FB_ARM__'...instructionsforARMOSes...#else'...instructionsforotherOSes#endif

DifferencesfromQB

NewtoFreeBASIC

Seealso

__FB_LINUX__

__FB_FREEBSD__

__FB_OPENBSD__

__FB_NETBSD__

__FB_CYGWIN__

__FB_DARWIN__

__Fb_Pcos__


__Fb_Asm__


Syntax__FB_ASM__

Description__FB_ASM__returnsastringequalto"intel"or"att"dependingonwhetherinlineassemblyblocksshouldusetheIntelformatortheGCC/AT&T;format.

Example

DimaAsLong#if__FB_ASM__="intel"AsmincdwordPtr[a]EndAsm#elseAsm"incl%0\n":"+m"(a)::EndAsm#endif

DifferencesfromQB

NewtoFreeBASIC

Seealso

CompilerOption:-asm

__Fb_Backend__


Syntax__FB_BACKEND__

DescriptionDefinedtoeither"gas"or"gcc",dependingonwhichbackendwasspecifiedvia-gen.

DifferencesfromQB

DidnotexistinQB

__FB_BIGENDIAN__


Syntax__FB_BIGENDIAN__

DescriptionDefinewithoutavaluecreatedatcompiletimeifcompilingforabigendiantarget.

Itcanbeusedtocompilepartsoftheprogramonlyifthetargetisbigendian.

Example

#ifdef__FB_BIGENDIAN__'...instructionsonlyforbigendianmachines#else'...instructionsonlyforlittleendianmachines#endif

DifferencesfromQB

DidnotexistinQB

__FB_BUILD_DATE__

Intrinsicdefine(macrostring)setbythecompiler

Syntax__FB_BUILD_DATE__

DescriptionSubstitutedwiththequotedstringcontainingthedate(MM-DD-YYYY)thecompilerwasbuilton.

Example

Print"Thisprogramcompiledwithacompilerbuiltonthisdate:"

DifferencesfromQB

NewtoFreeBASIC

__FB_CYGWIN__


Syntax__FB_CYGWIN__

DescriptionDefinewithoutavaluecreatedatcompiletimeintheCygwinversionofthecompiler,orwhenthe-targetcygwincommandlineoptionisused.ItcanbeusedtocompilepartsoftheprogramonlyifthetargetisCygwin.

Example

#ifdef__FB_CYGWIN__'...instructionsonlyforCygwin...#else'...instructionsnotforCygwin...#endif

DifferencesfromQB

NewtoFreeBASIC

Seealso

__FB_LINUX__

__Fb_Win32_

__Fb_Unix__


__FB_DARWIN__


Syntax__FB_DARWIN__

DescriptionDefinewithoutavaluecreatedatcompiletimeintheDarwinversionofthecompiler,orwhenthe-targetdarwincommandlineoptionisused.ItcanbeusedtocompilepartsoftheprogramonlyifthetargetisDarwin.

Example

#ifdef__FB_DARWIN__'...instructionsonlyforDarwin...#else'...instructionsnotforDarwin...#endif

DifferencesfromQB

NewtoFreeBASIC

Seealso

__FB_LINUX__

__FB_WIN32__

__Fb_Unix__


__FB_DEBUG__


Syntax__FB_DEBUG__

Description__FB_DEBUG__indicatesifthethegeneratedebuginformationoption'-g'wasspecifiedonthecommandlineatthetimeofcompilation.

Returnsnon-zero(-1)iftheoptionwasspecified.Returnszero(0)otherwise.

Example

#if__FB_DEBUG__0#printDebugmode#else#printReleasemode#endif

DifferencesfromQB

NewtoFreeBASIC

Seealso

__FB_ERR__

__FB_MT__

CompilerOption:-g

__FB_DOS__


Syntax__FB_DOS__

DescriptionDefinewithoutavaluecreatedatcompiletimeifcompilingfortheDOStarget.DefaultintheDOShostedversion,oractivewhenthe-targetdoscommandlineoptionisused.ItcanbeusedtocompilepartsoftheprogramonlyifthetargetisDOS.Note:theDOShostedversioncannotcompiletoothertargetsthanDOSbynow.

Example

#ifdef__FB_DOS__'...instructionsonlyforDOS...'...INT0x31#else'...instructionsnotforDOS...#endif

DifferencesfromQB

NewtoFreeBASIC

Seealso

__FB_LINUX__

__FB_WIN32__

__Fb_Pcos__

DOSrelatedFAQ


__FB_ERR__


Syntax__FB_ERR__

Description__FB_ERR__indicatesif-e,-ex,or-exxwasspecifiedonthecompilercommandlineatthetimeofcompilationofamodule.

Returnsoneofthefollowingvalues:

value description

0 '-e','-ex','-exx'notspecified

1 '-e'wasspecified

3 '-ex'wasspecified

7 '-exx'wasspecified

__FB_ERR__isalwaysdefined.

Example

'Examplecodetodemonstrateauseof__FB_ERR__Dimerr_command_lineAsUByteerr_command_line=__FB_ERR__SelectCaseerr_command_lineCase0Print"NoErrorCheckingenabledontheCommandLine!"Case1Print"SomeErrorCheckingenabledontheCommandLine!"Case3Print"QBasicstyleErrorCheckingenabledontheCommandLine!"Case7Print"ExtremeErrorCheckingenabledontheCommandLine!"

CaseElsePrint"SomeUnknownErrorlevelhasbeenset!"EndSelect

DifferencesfromQB

NewtoFreeBASIC

Seealso

__FB_MT__

__FB_DEBUG__

CompilerOption:-eCompilerOption:-exCompilerOption:-exxErrorHandling

__Fb_Fpmode__


Syntax__FB_FPMODE__

DescriptionDefinedas"fast"ifSSEfastarithmeticsisenabled,or"precise"otherwise.

Example

#if__FB_FPMODE__="fast"'...instructionsforusingfast-modemath...#else'...instructionsforusingnormalmath...#endif

DifferencesfromQB

NewtoFreeBASIC

Seealso

CompilerOption:-fpmode

__Fb_Fpu__


Syntax__FB_FPU__

DescriptionDefinedas"sse"ifSSEfloatingpointarithmeticsisenabled,or"x87"otherwise.

Example

#if__FB_FPU__="sse"'...instructionsonlyforSSE...#else'...instructionsnotforSSE...#endif

DifferencesfromQB

NewtoFreeBASIC

Seealso

__FB_SSE__

CompilerOption:-fpu

__FB_FREEBSD__


Syntax__FB_FREEBSD__

DescriptionDefinewithoutavaluecreatedatcompiletimeintheFreeBSDversionofthecompiler,orwhenthe-targetfreebsdcommandlineoptionisused.ItcanbeusedtocompilepartsoftheprogramonlyifthetargetisFreeBSD.

Example

#ifdef__FB_FREEBSD__'...instructionsonlyforFreeBSD...#else'...instructionsnotforFreeBSD...#endif

DifferencesfromQB

NewtoFreeBASIC

Seealso

__FB_LINUX__

__FB_WIN32__

__Fb_Unix__


__Fb_Gcc__


Syntax__FB_GCC__

DescriptionDefinedtotrue(-1)if-gengccisused,orfalse(0)otherwise.

DifferencesfromQB

DidnotexistinQB

__FB_LANG__


Syntax__FB_LANG__

Description__FB_LANG__indicateswhichlanguagecompatibilityoptionwassetatthetimeofcompilationofamodule.Bydefault__FB_LANG__willbesetto"fb".Thelanguagecompatibilityoptioncanbechangedusingone(ormore)ofthefollowingmethods:

-langcommandlineoption-forcelangcommandlineoption#langdirective$Langmetacommand

Returnsalowercasestringwithoneofthefollowingvalues:

value description

''fb'' FreeBASICcompatibility(default)

''qb'' QBASICcompatibility

''fblite'' FreeBASIClanguagecompatibility,withamoreQBASIC-compatiblecodingstyle

''deprecated'' FBCversion0.16compatibility

__FB_LANG__isalwaysdefined.

Example

''Setoptionexplicitalwayson

#ifdef__FB_LANG__#if__FB_LANG__"fb"

OptionExplicit#endif#else''Olderversion-beforelangfbOptionExplicit#endif

DifferencesfromQB

NewtoFreeBASIC

Seealso

__FB_VERSION__

#lang

CompilerOption:-langCompilerOption:-forcelangCompilerDialects

__FB_LINUX__


Syntax__FB_LINUX__

DescriptionDefinewithoutavaluecreatedatcompiletimewhencompilingtotheLinuxtarget.DefaultintheLinuxhostedversionofthecompiler,oractivewhenthe-targetlinuxcommandlineoptionisused.ItcanbeusedtocompilepartsoftheprogramonlyifthetargetisLinux.

Example

#ifdef__FB_LINUX__'...instructionsonlyforLinux...'...#libpath"/usr/X11/lib"#else'...instructionsnotforLinux...#endif

DifferencesfromQB

NewtoFreeBASIC

Seealso

__FB_DOS__

__FB_WIN32__

__Fb_Unix__


__FB_MAIN__


Syntax__FB_MAIN__

Description__FB_MAIN__isdefinedinthemainmoduleandnotdefinedinothermodules.

Themainmoduleisdeterminedbythecompileraseitherthefirstsourcefilelistedonthecommandlineorexplicitlynamedusingthe-moptiononthecommandline.

Example

#ifdef__FB_MAIN__#printCompilingthemainmodule#else#printCompilinganadditionalmodule#endif

DifferencesfromQB

NewtoFreeBASIC

Seealso

CompilerOption:-m#ifdef

#ifndef

__FB_MIN_VERSION__

Macrofunctiontotestminimumcompilerversion

Syntax#define__FB_MIN_VERSION__(major,minor,patch)_((__FB_VER_MAJOR__>major)or_((__FB_VER_MAJOR__=major)and((__FB_VER_MINOR__>minor)or_(__FB_VER_MINOR__=minorand__FB_VER_PATCH__>=patch_level))))

Usage__FB_MIN_VERSION__(major,minor,patch)

Parametersmajorminimummajorversiontotestminorminimumminorversiontotestpatchminimumpatchversiontotest

ReturnValueReturnszero(0)ifthecompilerversionislessthanthespecifiedversion,ornon-zero(-1)ifthecompilerversionisgreaterthanorequaltospecifiedversion

Description__FB_MIN_VERSION__testsforaminimumversionofthecompiler.

Example

#ifNot__FB_MIN_VERSION__(0,18,2)#errorfbcmustbeatleastversion0.18.2TocompileThismodule#endif

DifferencesfromQB

NewtoFreeBASIC

Seealso

#if

__FB_MT__


Syntax__FB_MT__

Description__FB_MT__indicatesifthethemultithreadedoption-mtwasspecifiedonthecommandlineatthetimeofcompilation.

Returnsnon-zero(-1)iftheoptionwasspecified.Returnszero(0)otherwise.

Example

#if__FB_MT__#printUsingmulti-threadedlibrary#else#printUsingSingle-threadedlibrary#endif

DifferencesfromQB

NewtoFreeBASIC

Seealso

__FB_DEBUG__

CompilerOption:-mt

__FB_NETBSD__


Syntax__FB_NETBSD__

DescriptionDefinewithoutavaluecreatedatcompiletimeintheNetBSDversionofthecompiler,orwhenthe-targetnetbsdcommandlineoptionisused.ItcanbeusedtocompilepartsoftheprogramonlyifthetargetisNetBSD.

Example

#ifdef__FB_NETBSD__'...instructionsonlyforNetBSD...#else'...instructionsnotforNetBSD...#endif

DifferencesfromQB

NewtoFreeBASIC

Seealso

__FB_LINUX__

__FB_WIN32__

__Fb_Unix__


__FB_OPENBSD__


Syntax__FB_OPENBSD__

DescriptionDefinewithoutavaluecreatedatcompiletimeintheOpenBSDversionofthecompiler,orwhenthe-targetopenbsdcommandlineoptionisused.ItcanbeusedtocompilepartsoftheprogramonlyifthetargetisOpenBSD.

Example

#ifdef__FB_OPENBSD__'...instructionsonlyforOpenBSD...#else'...instructionsnotforOpenBSD...#endif

DifferencesfromQB

NewtoFreeBASIC

Seealso

__FB_LINUX__

__FB_WIN32__

__Fb_Unix__


__FB_OPTION_BYVAL__


Syntax__FB_OPTION_BYVAL__

DescriptionIndicatesifparameterstoaFunctionorSubarepassedbyreferenceaswithorbyvalueaswithByValbydefaultwhenthebyvalue/byreferencespecifierisnotexplicitlystated.

__FB_OPTION_BYVAL__issettonon-zero(-1)ifbydefaultparametersarepassedvalue,andzero(0)ifbydefaultparametersarepassedbyreference.

ThedefaultforpassingparametersbyreferenceorbyvalueisdeterminedbythelangcommandlineoptionusedduringcompilationorusageofOptionByValsourcefile.

Example

#if(__FB_OPTION_BYVAL__0)#errorOptionByValmustNotbeusedWithThissource#endif

DifferencesfromQB

NewtoFreeBASIC

Seealso

ByVal

ByRef

OptionByVal

__FB_OPTION_DYNAMIC__


Syntax__FB_OPTION_DYNAMIC__

Description__FB_OPTION_DYNAMIC__isdefinedastrue(negativeone(-1))ifarecentOptionDynamicstatementor'$Dynamicmeta-commandwasissued.Otherwise,itisdefinedaszero(0).

Example

#if__FB_OPTION_DYNAMIC__0#errorThismodulemustNotuseOptionDynamic#endif

DifferencesfromQB

NewtoFreeBASIC

Seealso

OptionDynamic

OptionStatic

__FB_OPTION_ESCAPE__


Syntax__FB_OPTION_ESCAPE__

DescriptionIndicatesifbydefault,stringliteralsareprocessedforescapecharacterswhennotexplicitlyprefixedwiththe$Operatorfornon-escapedstrings,orthe!Operator

ThedefaultmethodforprocessingstringliteralsissetbyusageoftheoptionduringcompilationorusageofOptionEscapeinthesourcefile.

__FB_OPTION_ESCAPE__returnszero(0)iftheoptionhasnotbeenset.Returnsnon-zero(-1)iftheoptionhasbeenset.

Example

#if(__FB_OPTION_ESCAPE__0)#errorOptionEscapemustNotbeusedWithThisincludefile#endif

DifferencesfromQB

NewtoFreeBASIC

Seealso

OptionEscape

__FB_OPTION_EXPLICIT__


Syntax__FB_OPTION_EXPLICIT__

Description__FB_OPTION_EXPLICIT__indicatesifOptionExplicithasbeenusedpreviouslyinthesource.

Returnszero(0)iftheoptionhasnotbeenset.Returnsnon-zero(-1)iftheoptionhasbeenset.

Example

#if(__FB_OPTION_EXPLICIT__=0)#errorOptionExplicitmustusedWithThismodule#endif

DifferencesfromQB

NewtoFreeBASIC

Seealso

Dim

OptionExplicit

__Fb_Option_Gosub__


Syntax__FB_OPTION_GOSUB__

DescriptionIndicateshowGoSubandReturnwillbehandledatcompiletime.Iftheoptionisset(-1)thenGoSubisallowedandReturnisrecognizedasreturn-from-gosubonly.Iftheoptionisnotset(0)thenGoSubisnotallowedandReturnisrecognizedasreturn-from-procedureonly.

Thismacrovaluecanbechangedatcompiletime.OptionGosubwillsettheoption(enablegosubsupport)andOptionNogosubwillcleartheoption(disablegosubsupport).

__FB_OPTION_GOSUB__returnszero(0)iftheoptionhasnotbeenset.Returnsnon-zero(-1)iftheoptionhasbeenset.

Example

#if(__FB_OPTION_GOSUB__0)''turnoffgosubsupportOptionnogosub#endif

DialectDifferences

Defaultsto-1inthe-langqbdialectand0inallotherdialects.

DifferencesfromQB

NewtoFreeBASIC

Seealso

OptionGosub

OptionNogosub

__FB_OPTION_PRIVATE__


Syntax__FB_OPTION_PRIVATE__

DescriptionIndicatesifbydefaultFunction'sandSub'shavemodulescopeorglobalscopewhennotexplicitlyspecifiedwithPrivateorPublic.

ThedefaultscopespecifierforfunctionsandsubsissetbyusageofthecommandlineoptionduringcompilationorusageofOptionPrivateinthesourcefile.

__FB_OPTION_PRIVATE__returnszero(0)iftheoptionhasnotbeenset.zero(-1)iftheoptionhasbeenset.

Example

#if(__FB_OPTION_PRIVATE__0)#errorOptionPrivatemustNotbeusedWithThismodule#endif

DifferencesfromQB

NewtoFreeBASIC

Seealso

OptionPrivate

Private

Public

__FB_OUT_DLL__


Syntax__FB_OUT_DLL__

Description__FB_OUT_DLL__indicatesthatthespecifiedoutputfiletypeonthecompilercommandlineatthetimeofcompilationisasharedlibrary.

Returnsnon-zero(-1)iftheoutputisasharedlibrary.Returnszero(0)otherwise.

Onlyoneof__FB_OUT_DLL__,__FB_OUT_EXE__,__FB_OUT_LIB__,or__FB_OUT_OBJ__(-1).Allotherswillevaluatetozero(0).

Example

#if__FB_OUT_DLL__'...specificinstructionswhenmakingasharedlibrary(DLL)#else'...specificinstructionswhennotmakingasharedlibrary(DLL)#endif

DifferencesfromQB

NewtoFreeBASIC

Seealso

__FB_OUT_EXE__

__FB_OUT_LIB__

__FB_OUT_OBJ__

CompilerOption:-dll

__FB_OUT_EXE__


Syntax__FB_OUT_EXE__

Description__FB_OUT_EXE__indicatesthatthespecifiedoutputfiletypeonthecompilercommandlineatthetimeofcompilationisanexecutable.

Returnsnon-zero(-1)iftheoutputisanexecutable.Returnszero(0)otherwise.

Onlyoneof__FB_OUT_DLL__,__FB_OUT_EXE__,__FB_OUT_LIB__,or__FB_OUT_OBJ__non-zero(-1).Allotherswillevaluatetozero(0).

Example

#if__FB_OUT_EXE__'...specificinstructionswhenmakinganexecutable#else'...specificinstructionswhennotmakinganexecutable#endif

DifferencesfromQB

NewtoFreeBASIC

Seealso

__FB_OUT_DLL__

__FB_OUT_LIB__

__FB_OUT_OBJ__

__FB_OUT_LIB__


Syntax__FB_OUT_LIB__

Description__FB_OUT_LIB__indicatesthatthespecifiedoutputfiletypeonthecompilercommandlineatthetimeofcompilationisastaticlibrary.

Returnsnon-zero(-1)iftheoutputisastaticlibrary.Returnszero(0)otherwise.

Onlyoneof__FB_OUT_DLL__,__FB_OUT_EXE__,__FB_OUT_LIB__,or__FB_OUT_OBJ__zero(-1).Allotherswillevaluatetozero(0).

Example

#if__FB_OUT_LIB__'...specificinstructionswhenmakingastaticlibrary#else'...specificinstructionswhennotmakingastaticlibrary#endif

DifferencesfromQB

NewtoFreeBASIC

Seealso

__FB_OUT_EXE__

__FB_OUT_DLL__

__FB_OUT_OBJ__

CompilerOption:-lib

__FB_OUT_OBJ__


Syntax__FB_OUT_OBJ__

Description__FB_OUT_OBJ__indicatesthatthespecifiedoutputfiletypeonthecompilercommandlineatthetimeofcompilationisanobjectmodule.

Returnsnon-zero(-1)iftheoutputisanobjectmodule.Returnszero(0)otherwise.

Onlyoneof__FB_OUT_DLL__,__FB_OUT_EXE__,__FB_OUT_LIB__,or__FB_OUT_OBJ__Allotherswillevaluatetozero(0).

Example

#if__FB_OUT_OBJ__'...specificinstructionswhencompilingtoanobjectfileonly#else'...specificinstructionswhennotcompilingtoanobjectfileonly#endif

DifferencesfromQB

NewtoFreeBASIC

Seealso

__FB_OUT_EXE__

__FB_OUT_DLL__

__FB_OUT_LIB__

__Fb_Pcos__


Syntax__FB_PCOS__

DescriptionDefinecreatedatcompiletimeiftheOShasfilesystembehaviorstyledlikecommonPCOSes,e.g.DOS,Windows,OS/2,SymbianOS,possiblyothers.Driveletters,backslashes,thatstuff,otherwiseundefined.

Example

#ifdef__FB_PCOS__'...instructionsforPC-ishOSes...#else'...instructionsforotherOSes#endif

DifferencesfromQB

NewtoFreeBASIC

Seealso

__FB_WIN32__

__FB_DOS__

__FB_XBOX__

__Fb_Unix__


__FB_SIGNATURE__


Syntax__FB_SIGNATURE__

DescriptionSubstitutedbyasignatureofthecompilerwhereused.

Example

Print__FB_SIGNATURE__

FreeBASIC0.21.1

DifferencesfromQB

NewtoFreeBASIC

Seealso

__FB_VERSION__

__FB_WIN32__

__FB_LINUX__

__FB_DOS__

__FB_SSE__


Syntax__FB_SSE__

DescriptionDefinewithoutavaluecreatedatcompiletimeifSSEfloatingpointarithmeticsisenabled.

Example

#ifdef__FB_SSE__'...instructionsonlyforSSE...#else'...instructionsnotforSSE...#endif

DifferencesfromQB

NewtoFreeBASIC

Seealso

__Fb_Fpu__

CompilerOption:-fpu

__Fb_Unix__


Syntax__FB_UNIX__

DescriptionDefinecreatedatcompiletimeiftheOSisreasonablyenoughlikeUNIXthatyoucancallitUNIX,otherwiseundefined.

Example

#ifdef__FB_UNIX__'...instructionsforUNIX-familyOSes...#else'...instructionsforotherOSes#endif

DifferencesfromQB

NewtoFreeBASIC

Seealso

__FB_LINUX__

__FB_FREEBSD__

__FB_OPENBSD__

__FB_NETBSD__

__FB_CYGWIN__

__FB_DARWIN__

__Fb_Pcos__


__Fb_Vectorize__


Syntax__FB_VECTORIZE__

DescriptionDefinedasthevectorisationlevelnumbersetbythe-veccommand-lineoption.

Example

#if__FB_VECTORIZE__=2'...instructionsonlyforvectorizationlevel2...#else'...#endif

DifferencesfromQB

NewtoFreeBASIC

Seealso

CompilerOption:-vec

__FB_VER_MAJOR__


Syntax__FB_VER_MAJOR__

Description__FB_VER_MAJOR__willreturnthemajorversionofFreeBASICcurrentlybeingused.0.90,andwillremain0untilFreeBASICversion1.0isreleased.

Example

DimfbMajorVersionAsIntegerDimfbMinorVersionAsIntegerDimfbPatchVersionAsInteger

fbMajorVersion=__FB_VER_MAJOR__fbMinorVersion=__FB_VER_MINOR__fbPatchVersion=__FB_VER_PATCH__

Print"WelcometoFreeBASIC"&fbMajorVersion&"."

DifferencesfromQB

NewtoFreeBASIC

Seealso

__FB_VER_MINOR__

__FB_VER_PATCH__

__FB_VER_MINOR__


Syntax__FB_VER_MINOR__

Description__FB_VER_MINOR__willreturntheminorversionofFreeBASICcurrentlybeingused.ForFreeBASICversion0.90.1,forexample,theminorversionnumberis90.

Example




DifferencesfromQB

NewtoFreeBASIC

Seealso

__FB_VER_MAJOR__

__FB_VER_PATCH__

__FB_VER_PATCH__


Syntax__FB_VER_PATCH__

Description__FB_VER_PATCH__willreturnthepatch/subversion/revisionnumbertheversionofFreeBASICcurrentlybeingused.ForFreeBASIC0.18,forexample,thereweresubversions1,2,3,4,5and6,resultinginversions0.18.1through0.18.6.

Example




DifferencesfromQB

NewtoFreeBASIC

Seealso

__FB_VER_MAJOR__

__FB_VER_MINOR__

__FB_VERSION__


Syntax__FB_VERSION__

DescriptionSubstitutedbytheversionnumberofthecompilerwhereused.

Example

#if__FB_VERSION__<"0.18"#errorPleasecompileWithFBversion0.18Orabove#endif

Thiswillstopthecompilationifthecompilerversionisbelow0.18

DifferencesfromQB

DidnotexistinQB

Seealso

__FB_SIGNATURE__

__FB_WIN32__

__FB_LINUX__

__FB_DOS__

__FB_WIN32__


Syntax__FB_WIN32__

DescriptionDefinewithoutavaluecreatedatcompiletimeifcompilingtotheWin32target.DefaultinWin32hostedversion,oractiveifthe-targetwin32commandlineoptionisused.ItcanbeusedtocompilepartsoftheprogramonlyifthetargetisWin32.

Example

#ifdef__FB_WIN32__'...instructionsonlyforWin32...'...GetProcAddress...#else'...instructionsnotforWin32...#endif

DifferencesfromQB

NewtoFreeBASIC

Seealso

__FB_DOS__

__FB_LINUX__

__Fb_Pcos__


__FB_XBOX__


Syntax__FB_XBOX__

DescriptionDefinewithoutavaluecreatedatcompiletimewhenthe-targetxboxcommandlineoptionisused.ItcanbeusedtocompilepartsoftheprogramonlyifthetargetisXbox.

Example

#ifdef__FB_XBOX__'...instructionsonlyforXbox...#else'...instructionsnotforXbox...#endif

DifferencesfromQB

NewtoFreeBASIC

Seealso

__FB_LINUX__

__FB_WIN32__


__FILE__


Syntax__FILE__

DescriptionSubstitutedwiththequotedsourcefilenamewhereused.

Anexampleofnormaluseistoreportwrongvaluesindebugging.

Example

DimaAsIntegerIfa

__FILE_NQ__


Syntax__FILE_NQ__

DescriptionSubstitutedwiththenon-quotedsourcefilenamewhereused.

Example

#print__FILE_NQ__

DifferencesfromQB

NewtoFreeBASIC

Seealso

__FILE__

__FUNCTION_NQ__

__LINE__

__FUNCTION__


Syntax__FUNCTION__

DescriptionSubstitutedwiththequotednameofthecurrentfunctionblockwhereused.

Itsnormaluseistoreportwrongvaluesindebugging.

If__FUNCTION__isusedatthemodulelevel,thefunctionnamegivenwillbe"__FB_MODLEVELPROC__"foradifferentmodule.

Example

DimaAsInteger

'...

Ifa<0Then''thisshouldn'thappenPrint"Error:a="&a&"in"&__FILE__&EndIf

Error:a=-32767intest.bas(__FB_MAINPROC__)line47

DifferencesfromQB

DidnotexistinQB

Seealso

__FILE__

__FUNCTION_NQ__

__LINE__

__FUNCTION_NQ__


Syntax__FUNCTION_NQ__

DescriptionSubstitutedwiththenon-quotednameofthecurrentfunctionblockwhereused.

If__FUNCTION_NQ__isusedatthemodulelevel,thefunctionnamegivenwillbe__FB_MAINPROC__forthemainmodule,or__FB_MODLEVELPROC__foradifferentmodule.Thisisnottheactualfunctionnamethough,soit'snotasusefulthere.

Example

SubMySubPrint"Addressof"+__FUNCTION__+"is";PrintHex(@__FUNCTION_NQ__)EndSub

MySub

AddressofMYSUBis4012D0

DifferencesfromQB

DidnotexistinQB

Seealso

__FILE_NQ__

__FUNCTION__

__LINE__

__LINE__


Syntax__LINE__

DescriptionSubstitutedwiththecurrentlinenumberofthesourcefilewhereused.

Itsnormaluseistoreportwrongvaluesindebugging.

Example

DimaAsInteger

Ifa<0ThenPrint"Error:a="&a&"in"&__FILE__&EndIf

Error:a=-32767intest.bas(MAIN)line47

DifferencesfromQB

DidnotexistinQB

Seealso

__FILE__

__FUNCTION__

__PATH__


Syntax__PATH__

DescriptionSettothequotedabsolutepathofthesourcefileatthetimeofcompilation.

Example

'Tellthecompilertoseachthesourcefile's'directoryforlibraries

#libpath__PATH__

DifferencesfromQB

NewtoFreeBASIC

Seealso

__FILE__

__TIME__


Syntax__TIME__

DescriptionSubstitutesthecompilertimeinaliteralstring(24clock,"hh:mm:ss"format)whereused.

Example

Print"CompileTime:"&__TIME__

CompileTime:13:42:57

DifferencesfromQB

NewtoFreeBASIC

Seealso

__DATE__

__Date_Iso__

Time

#Assert

Preprocessorconditionaldirective

Syntax#assertcondition

ParametersconditionAconditionalexpressionthatisassumedtobetrue

DescriptionAssertsthetruthofaconditionalexpressionatcompiletime.Ifconditionisfalse,compilationwillstopwithanerror.

ThisstatementdiffersfromtheAssertmacrointhat#assertisevaluatedatcompile-timeandAssertisevaluatedatrun-time.

Example

ConstMIN=5,MAX=10#assertMAX>MIN''causeacompile-timeerrorifMAX

#define

Preprocessordirectivetodefineamacro

Syntax#defineidentifierbody#defineidentifier([parameters])body#defineidentifier([parameters,]Variadic_Parameter...)body

Description#defineallowstodeclaretext-basedpreprocessormacros.Oncethecompilerhasseena#define,itwillstartreplacingfurtheroccurrencesofidentifierwithbodyTheexpansionisdonerecursively,untilthereisnothingmoretoexpandandthecompilercancontinueanalyzingtheresultingcode.#undefcanbeusedtomakethecompilerforgetabouta#define.

Parametersturnadefineintoafunction-likemacro,allowingtextargumentstobepassedtothemacro.Anyoccurrencesoftheparameternamesinthebodywillbereplacedbythegivenargumenttextduringexpansion.The#Stringizeoperatorcanbeusedonmacroparameterstoturnthemintostringliterals,andthe##Concatenateoperatorcanbeusedtomergetokenstogether.

Note:Inthefunction-likemacrodeclaration,theidentifiershouldbefollowedbytheopeningparentheses(()immediatelywithoutanywhite-spaceinbetween,otherwisethecompilerwilltreatitaspartofthebody.

Definesarescoped;theyareonlyvisibleinthescopetheyweredefinedin.Ifdefinedatmodulelevel,thedefineisvisiblethroughoutthemodule.Iftheidentifierisdefinedinsideacompoundstatementhavingscope(Sub,For..Next,While..Wend,Do..Loop,Scope..EndScopeidentifierdefineisonlyvisiblewithinthatscope.Namespacesontheotherhanddonothaveanyeffectonthevisibilityofadefine.

Identifierscanbecheckedforwith#ifdefandothers,whichcanbeusedtohidepartsofcodefromthecompiler(conditionalcompiling).

Theresultofmacroexpansioncanbecheckedbyusingthe-ppcompileroption.

#definesareoftenusedtodeclareconstants.TheConststatementisatype-safealternative.

Example

''Definitionandcheck#defineDEBUGGING#ifdefDEBUGGING'...statements#endif

''Simpledefinition/textreplacement#defineFALSE0#defineTRUE(NotFALSE)

''Function-likedefinition#defineMyRGB(R,G,B)(((R)Shl16)Or((G)Shl8)Or(B))PrintHex(MyRGB(&hff,&h00,&hff))

''Linecontinuationandstatementsinadefinition#defineprintval(bar)_Print#bar;"=";bar

''#definesarevisibleonlyinthescopewheretheyaredefinedScope#defineLOCALDEF1EndScope

#ifndefLOCALDEF#PrintLOCALDEFIsNotdefined#endif

''namespaceshavenoeffectonthevisibilityofadefineNamespacefoo#defineNSDEFEndNamespace

#ifdefNSDEF#PrintNSDEFIsdefined

#endif

DifferencesfromQB

NewtoFreeBASIC

Seealso

#macro

#PreprocessorStringize

##PreprocessorConcatenate

#ifdef

#undef

Const

...

#else


Syntax#if(expression)'ConditionallyincludedstatementsifexpressionisTrue#else'ConditionallyincludedstatementsifexpressionisFalse#endif

Description#elsecanbeaddedtoan#if,#ifdef,or#ifndefblocktoprovideanalternateresulttotheconditionalexpression.

Example

#defineMODULE_VERSION1DimaAsString#if(MODULE_VERSION>0)a="Release"#elsea="Beta"#endifPrint"Programis";a

DifferencesfromQB

NewtoFreeBASIC

Seealso

#define

#macro

#if

#elseif#endif#ifdef

#ifndef

#undef

defined

#elseif


Syntax#if(expression1)'Conditionallyincludedstatementsifexpression1isTrue#elseif(expression2)'Conditionallyincludedstatementsifexpression2isTrue#else'Conditionallyincludedstatementsifboth'expression1andexpression2areFalse#endif

Description#elseifcanbeaddedtoan#ifblocktoprovideanadditionalconditions.

Example

#defineWORDSIZE16#if(WORDSIZE=16)'Dosomesome16bitstuff#elseif(WORDSIZE=32)'Dosomesome32bitstuff#else#errorWORDSIZEmustbesetTo16Or32#endif

DifferencesfromQB

NewtoFreebasic

Seealso

#define

#macro

#if

#else#endif#ifdef

#ifndef

#undef

defined

#endif


Syntax#endif

DescriptionEndsagroupofconditionaldirectives

See#if,#ifdef,or#ifndefforexamplesofusage.

Example

#defineDEBUG_LEVEL1#if(DEBUG_LEVEL=1)'Conditionalstatements#endif

DifferencesfromQB

NewtoFreeBASIC

Seealso

#define

#macro

#if

#else#elseif#ifdef

#ifndef

#undef

defined

#Macro...#Endmacro

Preprocessordirectivetodefineamultilinemacro

Syntax#macroidentifier([parameters])body#endmacro

#macroidentifier([parameters,]Variadic_Parameter...)body#endmacro

Description#macroisthemulti-lineversionof#define.

Example

''macroasanexpressionvalue#macroPrint1(a,b)a+b#endmacro

PrintPrint1("Hello","World")

''Output:''HelloWorld!

''macroasmultiplestatements#macroPrint2(a,b)Printa;Print"";Printb;Print"!"#endmacro

Print2("Hello","World")

''Output:''HelloWorld!

DifferencesfromQB

NewtoFreeBASIC

Seealso

#define

#ifdef

#undef

#error

Preprocessordiagnosticdirective

Syntax#errorerror_text

Parameterserror_textThedisplaymessage

Description#errorstopscompilinganddisplayserror_textwhencompilerfindsit.

Thiskeywordmustbesurroundedbyan#if...#endif,sothecompilercanreach#erroronlyifismet.

Example

#definec1

#ifc=1#errorBadvalueofc#endif

DifferencesfromQB

NewtoFreeBASIC

Seealso

#if

#print

#Assert

#if


Syntax#if(expression)'Conditionallyincludedstatements#endif

DescriptionConditionallyincludesstatementsatcompiletime.

Statementscontainedwithinthe#if/#endifblockareincludedifexpressionTrue(non-zero)andexcluded(ignored)ifexpressionevaluatestoFalse(

ThisconditionaldirectivediffersfromtheIfconditionalstatementinthatatcompile-timeandIfisevaluatedatrun-time.

Example

#defineDEBUG_LEVEL1#if(DEBUG_LEVEL>=2)'ThislineisnotcompiledsincetheexpressionisFalsePrint"Startingapplication"#endif

DifferencesfromQB

NewtoFreeBASIC

Seealso

#define

#macro

#else#elseif#endif#ifdef

#ifndef

#undef

defined

#Assert

#ifdef


Syntax#ifdefsymbol'Conditionallyincludedstatements#endif


Statementswithinthe#ifdef...#endifblockareincludedifsymbolisdefinedandexcluded(ignored)ifsymbolisnotdefined.

#ifdefsymbolisequivalentto#ifdefined(symbol)

Example

#define_DEBUG#ifdef_DEBUG'Specialstatementsfordebugging#endif

DifferencesfromQB

NewtoFreebasic

Seealso

#define

#macro

#if

#else

#elseif#endif#ifndef

#undef

defined

#ifndef


Syntax#ifndefsymbol'Conditionallyincludedstatements#endif


Statementswithinthe#ifndef...#endifblockareincludedifsymbolisnotdefinedandexcluded(ignored)ifsymbolisdefined.

#ifndefsymbolisequivalentto#ifNotdefined(symbol)

Example

#ifndef__MYFILE_BI__#define__MYFILE_BI__'Declarations#endif

DifferencesfromQB

NewtoFreeBASIC

Seealso

#define

#macro

#if

#else

#elseif#endif#ifdef

#undef

defined

#inclib

Preprocessordirective

Syntax#inclib"libname"

DescriptionIncludesalibraryinthelinkingprocessasiftheuserspecified-llibnamecommandline.

Example

''incompletecodesnippet

''thiswillincludelibmystuff.ainthelinkprocess#inclib"mystuff"

DifferencesfromQB

NewtoFreeBASIC

Seealso

#include

CompilerOption:-lCompilerOption:-p

#include

Preprocessorstatementtoincludecontentsofanothersourcefile

Syntax#include[once]"file"

Description#includeinsertssourcecodefromanotherfileatthepointwherethe#includedirectiveappears.Thishastheeffectofcompilingthesourcecodefromtheincludefileasthoughitwerepartofthesourcefilethatincludesit.Oncethecompilerhasreachedtheendoftheincludefile,theoriginalsourcefilecontinuestobecompiled.

Thisisusefultoremovecodefromafileandseparateitintomorefiles.Itisusefultohaveasinglefilewithdeclarationsinaprogramformedbyseveralmodules.Youmayincludefileswithinanincludefile,althoughavoidincludingtheoriginalfileintoitself,thiswillnotproducevalidresults.Typically,includefileswillhaveanextensionof.biandaremainlyusedfordeclaringsubs/functions/variablesofalibrary,butanyvalidsourcecodemaybepresentinanincludefile.

Theoncespecifiertellsthecompilertoincludethefileonlyonceevenifitisincludedseveraltimesbythesourcecode.

$Includeisanalternativeformofinclude,existingonlyforcompatibilitywithQuickBASIC.Itisrecommendedtouse#includeinstead.

Thecompilerwillautomaticallyconvertpathseparatorcharacters('/'and'\')asneededtoproperlyloadthefile.Thefilenamenamemaybeanabsoluteorrelativepath.

Forrelativepaths,orwherenopathisgivenatall,theincludefileissearchforinthefollowingorder:

RelativefromthedirectoryofthesourcefileRelativefromthecurrentworkingdirectory

Relativefromadditiondirectoriesspecifiedwiththe-icommandlineoptionTheincludefolderoftheFreeBASICinstallation(FreeBASIC\incwhereFreeBASICisthefolderwherethefbcexecutableislocated)

Example

'header.bifileTypeFooTypeBarAsByteBarbequeAsByteEndType

'main.basfile#include"header.bi"

DimFooAsFooType

Foo.Bar=1Foo.Barbeque=2

DifferencesfromQB

NewtoFreeBASIC

Seealso

#define

#inclib

CompilerOption:-iCompilerOption:-include

#lang

Preprocessorstatementtosetthecompilerdialect.

Syntax#lang"lang"

Parameters"lang"Thedialecttoset,enclosedindoublequotes,andmustbeoneof"fb""fblite","qb",or"deprecated".

DescriptionIfthe-forcelangoptionwasnotgivenonthecommandline,#langcanbeusedtosetthedialectforthesourcemoduleinwhichitappears.Atmosttwopasseswillbemadeonthesourcemodule.Onthefirstpass,ifthespecifieddialectisanythingotherthanthedefaultdialect(chosenwith-lang,or"fb"bydefault),thecompilerwillresettheparserforanotherpassandrestartcompilationatthebeginningofthesourcemodule.Ifthisdirectiveisencounteredagainonthesecondpass,andthespecifieddialectdoesnotmatchthenewcurrentdialect,awarningisissuedandcompilationcontinues.Ifanyerrorswereencounteredonthefirstpass,thecompilerwillnotattemptasecondpass."

#langmaynotbeusedinanycompoundstatement,scope,orsubroutine.However,itmaybenestedinmodulelevelpreprocessorstatementsorusedinanincludefile.

Thereiscurrentlynorestrictiononwherethisdirectivemaybeplacedinasourcemodule.Infuturethismaychange,thereforebestpracticewouldbetousethisdirectivebeforethefirstdeclaration,definition,orexecutablestatementinthesource.

Thisdirectiveoverridesthe-langoptionifitwasgivenonthecommandline.However,ifthe-forcelangoptionwasgivenonthecommandline,thisdirectivewillhavenoeffect.Awarningisissued,

thedirectiveisignored,andcompilationwillcontinue.Thisallowstheusertoexplicitlyoverride#langdirectives.

Example

#lang"fblite"

DifferencesfromQB

NewtoFreeBASIC

Seealso

$Lang

__FB_LANG__

CompilerOption:-langCompilerOption:-forcelangFreeBASICDialects

#libpath

Preprocessorstatementtoaddasearchpathforlibraries

Syntax#libpath"path"

DescriptionAddsalibrarysearchpathtothelinker'slistofsearchpathsasifithadbeenspecifiedonthecommandlinewiththe'-p'option.

Pathsarerelativetotheworkingdirectorywherefbcwasinvokedandnotrelativetothedirectoryofthesourcefile.

Noerrorisgeneratedifthepathdoesnotexistandcompilationandlinkingwillcontinue.

Example

'searchthelibdirectoryforexternallibraries#libpath"lib"

DifferencesfromQB

NewtoFreeBASIC

Seealso

#inclib

#include

CompilerOption:-p

#line

Preprocessordirectivetosetthecurrentlinenumberandfilename

Syntax#linenumber["name"]

Parametersnumbernewlinenumber"name"newfilename(optional)

DescriptionInformsthecompilerofachangeinlinenumberandfilenameandupdatesthe__LINE__macrovaluesaccordingly.

Bothcompiletimemessagesandrun-timemessagesareaffectedbythisdirective.

ThisdirectiveallowsotherprogramstogeneratesourcecodefortheFreeBASICcompilerandhaveitreturnwarningand/orerrormessagesthatrefertotheoriginalsourceusedbytheotherprogram.

Example

#line155"outside.src"

Error1000

''Outputis:''Abortingduetoruntimeerror1000atline157ofoutside.src()

DifferencesfromQB

NewtoFreeBASIC

Seealso

__FILE__

__LINE__

#pragma

Preprocessordirective

Syntax#pragmaoption[=value]Or#pragmapush(option[,value])Or#pragmapop(option)

ParametersPossiblevaluesforoptionandrelatedvalues:

Option Value Description

msbitfields 0 Usebitfieldscompatiblewithgcc(default)

-1(oranyothernon-zerovalue) UsebitfieldscompatiblewiththoseusedinMicrosoftCcompilers

once N/A causethesourcefileinwhichthepragmaappearstobehaveasthoughitwasincludedwith#includeonce...

Ifvalueisnotgiven,thecompilerassumes-1(TRUE).

DescriptionAllowsthesettingofcompileroptionsinsidethesourcecode.

Pushsavesthecurrentvalueoftheoptionontoastack,thenassignsthenewrestorestheoptiontoitspreviousvalue,andremovesitfromthestack.Thismechanismallowsoptionstobechangedforacertainpartofsourcecode,regardlessofthesettingusedbythecontext,whichisespeciallyusefulinside#includeheaderfiles.

Example

''MSVC-

compatiblebitfields:savethecurrentsettingandthenenablethem#pragmapush(msbitfields)

''dosomethingthatrequiresMS-compatiblebitfieldshere

''restoreoriginalsetting#pragmapop(msbitfields)

DifferencesfromQB

NewtoFreeBASIC

Seealso

#include

#print

Preprocessordiagnosticdirective

Syntax#printtext

DescriptionCausescompilertooutputtexttoscreenduringcompilation.

Example

#printNowcompilingmodulefoo

DifferencesfromQB

NewtoFreeBASIC

Seealso

#error

#undef

Preprocessordirectivetoundefineamacro

Syntax#undefsymbol

DescriptionUndefinesasymbolpreviouslydefinedwith#define.

Canbeusedtoensurethatamacroorsymbolhasalimitedlifespananddoesnotconflictwithasimilarmacrodefinitionthatmaybedefinedlaterinthesourcecode.

(Note:#undefshouldnotbeusedtoundefinevariableorfunctionnamesusedinthecurrentfunctionscope.Thenamesareneededinternallybythecompilerandremovingthemcancausestrangeandunexpectedresults.)

Example

#defineADD2(a_,b_)((a_)+(b_))PrintADD2(1,2)'Macronolongerneededsogetridofit...#undefADD2

DifferencesfromQB

NewtoFreebasic

Seealso

#define

#macro

#if

#else#elseif#endif#ifdef

#ifndef

defined

$Dynamic

Metacommandtochangethewayarraysareallocated

Syntax'$DynamicorRem$Dynamic

Description'$Dynamicisametacommandthatspecifiesthatanyfollowingarraydeclarationsarevariable-length,whethertheyaredeclaredwithconstantsubscriptrangesornot.Thisremainsineffectfortherestofthemoduleinwhich'$Dynamicisused,andcanbeoverriddenwith'$Static.ItisequivalenttotheOptionDynamicstatement.

Example

'compilewith-langfbliteorqb

#lang"fblite"

'$DYNAMICDima(100)'......ReDima(200)

DialectDifferences

Onlyavailableinthe-langfbliteand-langqbdialects.

DifferencesfromQB

Whenusedinsidecommentsitmustbethefirsttoken

Seealso

$Static

Dim

ReDim

Erase

OptionDynamic

$Include

Metacommandstatementtoincludecontentsofanothersourcefile

Syntax'$Include[once]:'file'orRem$Include[once]:'file'

Description$Includeinsertssourcecodefromanotherfileatthepointwherethe$Includemetacommandappears.Thishastheeffectofcompilingthesourcecodefromtheincludefileasthoughitwerepartofthesourcefilethatincludesit.Oncethecompilerhasreachedtheendoftheincludefile,theoriginalsourcefilecontinuestobecompiled.

Theoncespecifiertellsthecompilertoincludethefileonlyonceevenifitisincludedseveraltimesbythesourcecode.

'$Include:existsforcompatibilitywithQuickBASIC.Itisrecommendedtouse#includeinstead.

Example

'header.bifileTypeFooTypeBarAsByteBarbequeAsByteEndTypeDimFooAsFooType

''compilewith-langfbliteorqb

#lang"fblite"

''main.basfile

'$INCLUDE:"header.bi"

Foo.Bar=1Foo.Barbeque=2

DialectDifferences

Onlyavailableinthe-langfbliteand-langqbdialects.

DifferencesfromQB

None

Seealso

#include

$Static

Metacommandtochangethewayarraysareallocated

Syntax'$StaticorRem$Static

Description'$Staticisametacommandthatoverridesthebehaviorof$Dynamic,thatis,arraysdeclaredwithconstantsubscriptrangesarefixed-length.Thisremainsineffectfortherestofthemoduleinwhich'$Staticisused,andcanbeoverriddenwith$Dynamic.ItisequivalenttotheOptionStaticstatement.

Example

'compilewith-langfbliteorqb

#lang"fblite"

'$dynamicDima(100)'

Seealso

$Dynamic

Dim

Erase

ReDim

OptionDynamic

OptionStatic

$Lang

Metacommandstatementtosetthecompilerdialect.

Syntax'$lang:"lang"orRem$lang:"lang"

Parameters"lang"Thedialecttoset,enclosedindoublequotes,andmustbeoneof"fb""fblite","qb",or"deprecated".

DescriptionIfthe-forcelangoptionwasnotgivenonthecommandline,$Langcanbeusedtosetthedialectforthesourcemoduleinwhichitappears.Atmosttwopasseswillbemadeonthesourcemodule.Onthefirstpass,ifthespecifieddialectisanythingotherthanthedefaultdialect(chosenwith-lang,or"fb"bydefault),thecompilerwillresettheparserforanotherpassandrestartcompilationatthebeginningofthesourcemodule.Ifthismetacommandisencounteredagainonthesecondpass,andthespecifieddialectdoesnotmatchthenewcurrentdialect,awarningisissuedandcompilationcontinues.Ifanyerrorswereencounteredonthefirstpass,thecompilerwillnotattemptasecondpass.

$Langmaynotbeusedinanycompoundstatement,scope,orsubroutine.However,itmaybenestedinmodulelevelpreprocessorstatementsorusedinanincludefile.

Thereiscurrentlynorestrictiononwherethisdirectivemaybeplacedinasourcemodule.Infuturethismaychange,thereforebestpracticewouldbetousethisdirectivebeforethefirstdeclaration,definition,orexecutablestatementinthesource.

Thisdirectiveoverridesthe-langoptionifitwasgivenonthe

commandline.However,ifthe-forcelangoptionwasgivenonthecommandline,thisdirectivewillhavenoeffect.Awarningisissued,thedirectiveisignored,andcompilationwillcontinue.Thisallowstheusertoexplicitlyoverride$Langmetacommands.

ThismetacommandwasintroducedinFreeBASICversion0.20.0.OlderversionsofFB,andQuickBASIC,willtreatitasacommentandsilentlyignoreit.

Example

'$lang:"qb"

DifferencesfromQB

NewtoFreeBASICQBhandles'$lang:asanormalcomment

Seealso

#lang

__FB_LANG__

CompilerOption:-langCompilerOption:-forcelangFreeBASICDialects

Abs

Calculatestheabsolutevalueofanumber

SyntaxDeclareFunctionAbs(ByValnumberAsLong)AsLongDeclareFunctionAbs(ByValnumberAsUlong)AsUlongDeclareFunctionAbs(ByValnumberAsLongInt)AsLongIntDeclareFunctionAbs(ByValnumberAsULongInt)AsULongIntDeclareFunctionAbs(ByValnumberAsDouble)AsDouble

Usageresult=Abs(number)

ParametersnumberValuetofindtheabsolutevalueof.

ReturnValueTheabsolutevalueofnumber.

DescriptionTheabsolutevalueofanumberisitspositivemagnitude.Ifanumberisnegative,itsvaluewillbenegatedandthepositiveresultreturned.Forexample,Abs(-1)andAbs(1)bothreturn1.Therequirednumberargumentcanbeanyvalidnumericexpression.Unsignednumberswillbetreatedasiftheyweresigned,i.e.ifthehighestbitissetthenumberwillbetreatedasnegative,anditsvaluenegated.Thevaluereturnedwillbegreaterthanorequalto0,withtheexceptionofsignedintegerscontainingthelowestpossiblenegativevaluethatcanbestoredinitstype,inwhichcasenegatingitwilloverflowtheresult.

TheAbsunaryOperatorcanbeoverloadedwithuserdefinedtypes.

Example

DimnAsInteger

PrintAbs(-1)PrintAbs(-3.1415)PrintAbs(42)PrintAbs(n)

n=-69

PrintAbs(n)

Output:

13.141542069

DialectDifferences

Inthe-langqbdialect,thisoperatorcannotbeoverloaded.

DifferencesfromQB

None

Seealso

Sgn

Operator

Abstract

Declareabstractmethods

SyntaxTypetypenameExtendsbase_typenameDeclareAbstractSub|Function|Property|Operator...EndType

DescriptionAbstractisaspecialformofVirtual.Thedifferenceisthatabstractmethodsdonothaveabody,butjustthedeclaration.Essentiallythisallowsthedeclarationofaninterfacewhichcanbeimplementedbyvariousderivedtypes.

Inordertocallanabstractmethod,itmusthavebeenoverriddenandimplementedbyaderiveddatatype,orelsetheprogramwillabort.Asaresult,onlytypesthatimplementalltheabstractmethodsareallowedtocreateobjects.Forthesamereason,aconstructorshouldnotcallanunimplementedmethod.

Constructorscannotbeabstract,sincetheycannotbevirtual.Inaddition,abstractDestructorsarenotsupportedeither,becauseadestructorbody(nomatterwhetherimplicitorexplicit)isneededinordertocallbaseandfielddestructors.

Abstractsarecalled"purevirtual"inC++(unlikeFreeBASIC,C++allowspurevirtualstohaveabody,butaccessibleonlystatically).

Note:Inamulti-levelinheritance,asamenamedmethod(sameidentifierandsignature)canbedeclaredAbstract,Virtualornormal(withoutspecifier)ateachinheritancehierarchylevel.Whenthereismixingofspecifiers,theusualorderisabstract->virtual->normal,fromtoptobottomoftheinheritancehierarchy.Theaccesscontrol(Public/Protected/Private)ofanoverridingmethodisnottakenintoaccountbytheinternalpolymorphismprocess,butonlyfortheinitialcallatcompile-time.

Aderivedstaticmethodcannotoverrideabasevirtual/abstractmethod,butcanshadowanybasemethod(includingvirtual/abstract).

Example

TypeHelloextendsobjectDeclareabstractSubhi()EndType

TypeHelloEnglishextendsHelloDeclareSubhi()EndType

TypeHelloFrenchextendsHelloDeclareSubhi()EndType

TypeHelloGermanextendsHelloDeclareSubhi()EndType

SubHelloEnglish.hi()Print"hello!"EndSub

SubHelloFrench.hi()Print"Salut!"EndSub

SubHelloGerman.hi()Print"Hallo!"EndSub

Randomize(Timer())

DimAsHelloPtrh

ForiAsInteger=0To9SelectCase(Int(Rnd()*3)+1)Case1h=NewHelloFrenchCase2h=NewHelloGermanCaseElseh=NewHelloEnglishEndSelect

h->hi()DeletehNext

DialectDifferences

Onlyavailableinthe-langfbdialect.

DifferencesfromQB

NewtoFreeBASIC

Seealso

Virtual

Type

Extends

Object

Access

ClauseoftheOpenstatementtospecifyrequestedprivileges

SyntaxOpenfilenameforBinaryAccess{Read|Write|ReadWrite}as[#]

UsageopenfilenameforbinaryAccessReadas#filenumopenfilenameforbinaryAccessWriteas#filenumopenfilenameforbinaryAccessReadWriteas#filenum

ParametersReadOpenthefilewithonlyreadprivileges.WriteOpenthefilewithonlywriteprivileges.ReadWriteOpenthefilewithreadandwriteprivileges.

DescriptionAccessisusedwiththeOpenstatementtorequestread,write,orreadandwriteprivileges.Accessclauseisnotspecified,ReadWriteisassumed.

Example

Thisexampleshowshowtoopenthefile"data.raw"withReadandthen"data.out"withaccess,inBinarymode,inanopenfilenumberreturnedbyFreeFile.

DimAsIntegero

''getanopenfilenumber.o=FreeFile''openfileforread-onlyaccess.Open"data.raw"ForBinaryAccessReadAs#o

''makeabufferinmemorythatstheentiresizeofthefileDimAsUBytefile_char(LOF(o)-1)

''getthefileintothebuffer.Get#o,,file_char()Close''getanotheropenfilenumber.o=FreeFile''openfileforwrite-onlyaccess.Open"data.out"ForBinaryAccessWriteAs#o

''putthebufferintothenewfile.Put#o,,file_char()Close

Print"Copiedfile""data.raw""tofile""data.out"""

Sleep

DifferencesfromQB

Noneknown.

Seealso

Open

Read

Write

Acos

Findsthearccosineofanangle

SyntaxDeclareFunctionAcos(ByValnumberAsDouble)AsDouble

Usageresult=Acos(number)

ParametersnumberAcosinevalueintherange[-1..1].

ReturnValueThearccosineofnumber,inradians,intherange[0..Pi].

DescriptionAcosreturnsthearccosineoftheargumentnumberasaDoublewithintherangeof0totheinverseoftheCosfunction.Thereturnedangleismeasuredinradians

Example

DimhAsDoubleDimaAsDoubleInput"Pleaseenterthelengthofthehypotenuseofatriangle:"Input"Pleaseenterthelengthoftheadjacentsideofthetriangle:"Print""Print"Theanglebetweenthesidesis";Acos(a/Sleep

Theoutputwouldlooklike:

Pleaseenterthelengthofthehypotenuseofatriangle:5

Pleaseenterthelengthoftheadjacentsideofthetriangle:4

Theanglebetweenthesidesis0.6435011087932843

DialectDifferences

Notavailableinthe-langqbdialectunlessreferencedwiththealias

DifferencesfromQB

NewtoFreeBASIC

Seealso

Cos

ABriefIntroductionToTrigonometry

Add

ParametertothePutgraphicsstatementwhichselectsadditionastheblittingmethod

SyntaxPut[target,][STEP](x,y),source[,(x1,y1)-(x2,y2)],,multiplier]

ParametersAddRequired.multiplierOptionalvaluebetween0and255.Thesourcepixelsarepremultipliedby(multiplier/256)beforebeingadded.Ifomitted,thisvaluedefaultsto255.

DescriptionAddselectsadditionasthemethodforblittinganimagebuffer.Foreachsourceandtargetpixel,thevaluesofeachrespectivecomponentareaddedtogethertoproducetheresult.Theadditionissaturated-i.e.ifthesumofthetwovaluesis256ormore,thenitwillbecroppeddownto255.

Thismethodwillworkinallcolormodes.Maskcolors(color0forindexedimages,magenta(RGB(255,0,255))forfullcolorimages)willbeskipped,thoughfullcolorvaluesof0(RGBA(0,0,0,0))willhavealsohavenoeffect.

Example

''openagraphicswindowScreenRes320,200,16

''createaspritecontainingacircleConstAsIntegerr=32DimcAsAnyPtr=ImageCreate(r*2+1,r*2+Circlec,(r,r),r,RGB(255,255,192),,,1,f

''putthespriteatthreedifferentmultipier''levels,overlappingeachotherinthemiddlePut(146-r,108-r),c,add,64Put(174-r,108-r),c,add,128Put(160-r,84-r),c,add,192

''freethememoryusedbythespriteImageDestroyc

''pausetheprogrambeforeclosingSleep

DifferencesfromQB

NewtoFreeBASIC

Seealso

Trans

Alpha

Custom

Put(Graphics)

Alias

ClauseoftheSubandFunctionstatementsthatprovidesanalternateinternalname

Syntax[Declare]{Sub|Function}usablenameAlias"alternatename"(...)

UsagedeclaresubusablenameAlias"alternatename"(...)or

declarefunctionusablenameAlias"alternatename"(...)orsubusablenameAlias"alternatename"(...)...endsuborfunctionusablenameAlias"alternatename"(...)...endfunction

DescriptionAliasgivesanalternatenametoaprocedure.Thisalternatenamecannotbeusedwithintheprogramtocalltheprocedure,butitisvisible(ifthefunctionisnotprivate)tothelinkerwhenlinkingwithcodewritteninotherlanguages.

AliasiscommonlyusedforproceduresinlibrarieswritteninotherlanguageswhensuchprocedurenamesarevalidintheotherlanguagebutinvalidinBASIC.WhenusingAliaswithDeclare,onlythealternatenameisusedbythelinker.

Differentlyfromnormalprocedurenames,Aliasdoesnotchangethecaseofthealternatename,soitisusefulwhenexternalcoderequiresanexportedfunctionwithaparticularnameorwithaparticularcase.

Example

IfthereisasubcalledxClearScreeninanexternallibraryandyouwanttoreferenceitwiththenametodoso:

DeclareSubClearVideoScreenAlias"xClearScreen"()

AproceduremeanttobeusedbyexternalCcode,exportedasMyExportedProc

FunctionMultiplyByFivecdeclAlias"MyExportedProc"ReturnParameter*5EndFunction

DifferencesfromQB

InQB,AliasonlyworkedwithDeclare.

Seealso

Declare

Export

Allocate

Allocatesablockofmemoryfromthefreestore

SyntaxDeclareFunctionAllocatecdecl(ByValcountAsUInteger)AsAny

Usageresult=Allocate(count)

ParameterscountThesize,inbytes,oftheblockofmemorytoallocate.

ReturnValueIfsuccessful,theaddressofthestartoftheallocatedmemoryisreturned.Otherwise,iftherequestedblocksizecouldnotbeallocated,orifcount<0,thenthenullpointer(0)isreturned.

DescriptionAttemptstoallocate,orreserve,countnumberofbytesfromthefreestore(heap).Thenewlyallocatedmemoryisnotinitialized.

Astheinitialvalueofnewlyallocatedmemoryisunspecified,Allocatestring,becausethestringdescriptorbeingnotcleared(containingrandomdata),thatmayinducecorruptedstringormore(tryingtowritetoarandomplaceinmemoryortryingtodeallocatearandompointer).containingstring)touseCAllocate(clearingmemory),orNew(callingconstructor)incaseofexplicitlyclearthedescriptor(settingto0)beforethefirststringuse.

ThepointerthatisreturnedisanAnyPtrandpointstothestartoftheallocatedmemory.Thispointerisguaranteedtobeunique,evenifcountiszero.

Allocatedmemorymustbedeallocated,orreturnedbacktothefreestore,with

Example

''ThisprogramusestheALLOCATE(...)functiontocreateabufferof15integersthatis''thenfilledwiththefirst15numbersoftheFibonacciSequence,thenoutputtothe''screen.NotethecalltoDEALLOCATE(...)attheendoftheprogram.

ConstintegerCountAsInteger=15

''Tryallocatingmemoryforanumberofintegers.''DimbufferAsIntegerPtrbuffer=Allocate(integerCount*SizeOf(Integer

If(0=buffer)ThenPrint"Error:unabletoallocatememory,quitting."End-1EndIf

''Primeandfillthememorywiththefibonaccisequence.''buffer[0]=0buffer[1]=1ForiAsInteger=2TointegerCount-1buffer[i]=buffer[i-1]+buffer[i-2]Next

''Displaythesequence.''ForiAsInteger=0TointegerCount-1Printbuffer[i];Next

Deallocate(buffer)End0

Outputis:

01123581321345589144233377

Itisimportanttofreeallocatedmemoryifit'snotgoingtobeusedanymore.Unusedmemorythatisn'tfreedissimplywastingmemory,andiftheaddressofthatmemoryissomehowoverwrittenorforgotten,thatmemorycanneverbefreed.Thisconditionisknownasamemoryleak,andshouldbeavoidedatallcosts.Notethatleakedmemoryisalwayscompletelyfreedwhentheapplicationterminates,eitherbyan"ordinary"exitorcrash,sotheleak"persists"onlyaslongastheapplicationruns,neverthelessit'sagoodhabittofreeanyallocatedmemoryinsideyourapplication.Thefollowingexampledemonstratesafunctionwithamemoryleak,wheretheaddressofallocatedmemoryislostandisn'tandcan'tbefreedanymore.Ifsuchafunctioniscalledfrequently,thetotalamountofmemorywastedcanaddupquickly.

''BadexampleofAllocateusage,causingmemoryleaks

SubBadAllocateExample()

DimpAsBytePtr

p=Allocate(420)''assignpointertonewmemory

p=Allocate(420)''reassignsamepointertodifferentmemory,''oldaddressislostandthatmemoryisleaked

Deallocate(p)

EndSub

''MainBadAllocateExample()''CreatesamemoryleakPrint"Memoryleak!"BadAllocateExample()''...andanotherPrint"Memoryleak!"End

PlatformDifferences

Thisprocedureisnotguaranteedtobethread-safe.

DialectDifferences

Notavailableinthe-langqbdialectunlessreferencedwiththealias

DifferencesfromQB

NewtoFreeBASIC

Seealso

CAllocate

Reallocate

Deallocate

Alpha

ParametertothePutgraphicsstatementwhichselectsalphablendingasthemethod

SyntaxPut[target,][STEP](x,y),source[,(x1,y1)-(x2,y2)],Put[target,][STEP](x,y),source[,(x1,y1)-(x2,y2)],

ParametersAlphaRequired.alphavalOptionalalphaparameterintherange[0..255].Overridesalphavaluesinindividualpixels.

DescriptionAlphaselectsalphablendingasthemethodforPuttinganimage.Iftheeachpixel,andthemaskcolor(magenta)willbetreatedastransparent.

Ifalphavalisnotspecified,Alphawillonlyworkin32-bitcolordepth,andPixelsusingthemaskcolorwillbetreatedasnormal,anddrawnwiththeirgivenalphavalue.

Alphaalsohasanothermodewhichallowsan8-bitimagetobePutontopofa32-bitimage.channelofthe32-bitimagewiththecontentsofthe8-bitimage.

Alphavaluesrangebetween0and255.Analphavalueof0willnotdrawtheimageatall.togetarangebetween2and256,andtheresultisthendividedby256togetavaluebetween1/128and1,whichisusedtocalculatetheexactvalueofeachpixelfromthesourceanddestinationpixels.Thus,255ispracticallyequivalenttodrawingusingPutwithTransblittingmode,0isequivalenttodoingnothingatall,andalltheotheralphavaluesblendisexpected.

ExampleThisexamplecomparesthetwodifferentAlphamodes,includinghowtheyreacttothemaskcolor

''Setupa32-bitscreenScreenRes320,200,32

''Drawcheckeredbackground

ForyAsInteger=0To199ForxAsInteger=0To319PSet(x,y),IIf((xShr2XoryShr2)AndNextxNexty

''MakeimagespriteforPuttingDimimgAsAnyPtr=ImageCreate(32,32,RGBA(0,0ForyAsSingle=-15.5To15.5ForxAsSingle=-15.5To15.5DimAsIntegerr,g,b,aIfy

''FreetheimagememoryImageDestroyimg

''WaitforakeypressSleep

Thisexampleshowsthespecialmethodforsettinga32-bitalphachannelusingan8-bitimage

DimAsAnyPtrimg8,img32DimAsIntegerx,y,i

''Setupan8-bitgraphicsscreenScreenRes320,200,8Fori=0To255Palettei,i,i,iNextiColor255,0

''Createan8-bitimageimg8=ImageCreate(64,64,0,8)Fory=0To63Forx=0To63DimAsSinglex2=x-31.5,y2=y-31.5DimAsSinglet=Sqr(x2^2+y2^2)/5PSetimg8,(x,y),Sin(t)^2*255NextxNexty

DrawString(16,4),"8-bitAlphasprite"Put(16,16),img8Sleep

''Setupa32-bitgraphicsscreenScreenRes320,200,32Fory=0To199Forx=0To319PSet(x,y),IIf(x-yAnd3,RGB(160,160NextxNexty

''Createa32-bit,fullyopaquespriteimg32=ImageCreate(64,64,0,32)Fory=0To63Forx=0To63PSetimg32,(x,y),RGB(x*4,y*4,128)NextxNexty

DrawString(16,4),"OriginalAlphachannel"Put(16,16),img32,Alpha

''Putanewalphachannelusingthe8-bitimagePutimg32,(0,0),img8,Alpha

DrawString(16,104),"NewAlphachannel"Put(16,116),img32,Alpha

''FreethememoryforthetwoimagesImageDestroyimg8ImageDestroyimg32

Sleep

DifferencesfromQB

NewtoFreeBASIC

Seealso

Put(Graphics)

Trans

Custom

OperatorAnd(Conjunction)

Returnsthebitwise-and(conjunction)oftwonumericvalues

SyntaxDeclareOperatorAnd(ByReflhsAsT1,ByRefrhsAsT2)AsRet

Usageresult=lhsAndrhs

ParameterslhsTheleft-handsideexpression.T1Anynumericorbooleantype.rhsTheright-handsideexpression.T2Anynumericorbooleantype.RetAnumericorbooleantype(varieswithT1andT2).

ReturnValueReturnsthebitwise-and(conjunction)ofthetwooperands.

DescriptionThisoperatorreturnsthebitwise-andofitsoperands,alogicaloperationthatresultsinavaluewithbitssetdependingonthebitsoftheoperands(forconversionofabooleantoaninteger,falseortruebooleanvaluebecomes0or-1integervalue).

Thetruthtablebelowdemonstratesallcombinationsofaboolean-andoperation:

LhsBit RhsBit Result

0 0 0

1 0 0

0 1 0

1 1 1

Noshort-circuitingisperformed-bothexpressionsarealwaysevaluated.

Thereturntypedependsonthetypesofvaluespassed.Byte,UByteandfloating-pointtypevaluesarefirstconvertedtoandright-handsidetypesdifferonlyinsignedness,thenthereturntypeisthesameastheleft-handsidetype(thetwotypesisreturned.Onlyiftheleftandright-handsidetypesareboth

Thisoperatorcanbeoverloadedforuser-definedtypes.

Example

'UsingtheANDoperatorontwonumericvaluesDimAsUBytenumeric_value1,numeric_value2numeric_value1=15'00001111numeric_value2=30'00011110

'Result=14=00001110Printnumeric_value1Andnumeric_value2Sleep

'UsingtheANDoperatorontwoconditionalexpressionsDimAsUBytenumeric_value1,numeric_value2numeric_value1=15numeric_value2=25

Ifnumeric_value1>10Andnumeric_value1<20ThenIfnumeric_value2>10Andnumeric_value2<20ThenSleep

'Thiswilloutput"Numeric_Value1isbetween10and20"because'bothconditionsoftheIFstatementistrue'ItwillnotoutputtheresultofthesecondIFstatementbecausethefirst'conditionistrueandthesecondisfalse.

DialectDifferences

Inthe-langqbdialect,thisoperatorcannotbeoverloaded.

DifferencesfromQB

None

Seealso

AndAlso

OperatorTruthTables

OperatorAndalso(ShortCircuitConjunction)

Returnstheshortcircuit-and(conjunction)oftwonumericvalues

SyntaxDeclareOperatorAndAlso(ByReflhsAsT1,ByRefrhsAsT2)As

Usageresult=lhsAndAlsorhs

ParameterslhsTheleft-handsideexpression.T1Anynumericorbooleantype.rhsTheright-handsideexpression.T2Anynumericorbooleantype.RetAnumericorbooleantype(varieswithT1andT2).

ReturnValueReturnstheshortcircuit-and(conjunction)ofthetwooperands.

DescriptionThisoperatorevaluatesthelefthandsideexpression.Iftheresultiszero,thenzeroisimmediatelyreturned.Iftheresultisnonzerothentherighthandsideisevaluated,andthelogicalresultfromthatisreturned.(forconversionofabooleantoaninteger,falseortruebooleanvaluebecomes0or-1integervalue)

Thetruthtablebelowdemonstratesallcombinationsofashortcircuit-andoperation,the'-'denotesthattheoperandisnotevaluated.

LhsValue RhsValue Result

0 - 0

nonzero 0 0

nonzero nonzero -1

Short-circuitingisperformed-onlyexpressionsneededtocalculatetheresultareevaluated.

ThereturntypeisalmostalwaysanInteger,ofthevalue0or-1,denotingfalseandtruerespectively.Exceptiftheleftandright-handsidetypesarebothBooleantypeisalsoBoolean.

Thisoperatorcannotbeoverloadedforuser-definedtypes.

Example

''UsingtheANDALSOoperatortoguardagainstarrayaccess''whentheindexisoutofrange

DimAsIntegerisprime(1To10)={__'123456789100,1,1,0,1,0,1,0,0,0_}

DimAsIntegernInput"Enteranumberbetween1and10:",n

''isprime()arraywillonlybeaccessedifnisinrangeIf(n>=1Andn

DifferencesfromQB

ThisoperatorwasnotavailableinQB.

Seealso

OrElse

And

OperatorTruthTables

And

ParametertothePutgraphicsstatementwhichusesabit-wiseAndastheblittingmethod

SyntaxPut[target,][STEP](x,y),source[,(x1,y1)-(x2,y2)],

ParametersAndRequired.

DescriptionTheAndmethodcombineseachsourcepixelwiththecorrespondingdestinationpixel,usingthebit-wiseAndfunction.Theresultofthisisoutputasthedestinationpixel.Thismethodworksinallgraphicsmodes.Thereisnomaskcolor,althoughcolorvalueswithallbitsset(255for8-bitpalettemodes,orRGBA(255,255,255,255)infull-colormodes)willhavenoeffect,becauseofthebehaviorofAnd.

Infull-colormodes,eachcomponent(red,green,blueandalpha)iskeptinadiscretesetofbits,sotheoperationcanbemadetoonlyaffectsomeofthechannels,bymakingsuretheallthevaluesoftheotherchannelsaresetto255.

Example

''openagraphicswindowScreenRes320,200,16Line(0,0)-(319,199),RGB(255,255,255),bf

''create3spritescontainingcyan,magentaandyellowcirclesConstAsIntegerr=32DimAsAnyPtrcc,cm,cycc=ImageCreate(r*2+1,r*2+1,RGBA(255,255cm=ImageCreate(r*2+1,r*2+1,RGBA(255,255cy=ImageCreate(r*2+1,r*2+1,RGBA(255,255Circlecc,(r,r),r,RGB(0,255,255),,,1,fCirclecm,(r,r),r,RGB(255,0,255),,,1,f

Circlecy,(r,r),r,RGB(255,255,0),,,1,f

''putthethreesprites,overlappingeachotherinthemiddlePut(146-r,108-r),cc,AndPut(174-r,108-r),cm,AndPut(160-r,84-r),cy,And

''freethememoryusedbythespritesImageDestroyccImageDestroycmImageDestroycy

''pausetheprogrambeforeclosingSleep

DifferencesfromQB

None

Seealso

And

Put(Graphics)

Any

Anyisusedasaplaceholderforatypeorvalueinvariousways.

SyntaxDimidentifierAsAnyPointer|PtrorDeclareSub|Functionidentifier(ByRefidentifierAsAny[,...])orDimidentifier(Any[,Any...])AsDataTypeor[Declare]{Sub|Function}proc_name(param(Any[,Any...])orDimidentifierAsDataType=AnyorNewDataType(Any)orNew(Address)DataType[count]{Any}orInStr|InStrRev(string,Anysubstring)

Description

Pointers:AspecialpointertypecalledtheAnyPtr(or"AnyPointer")allowspointingtoanyvariabletype.asaninstanceofDataType.PointerarithmeticisallowedonanAnyPtr

ApureAnyPtrhasnotypecheckingbythecompiler.Itcanbeimplicitlyconvertedtoandfromotherpointertypesthroughassignmentorparameterpassing.

Anyonitsownisnotavaliddatatypeforavariable.Also,itisillegaltodereferencean

ThisshouldnotbeconfusedwithVariant,aVisualBasicdatatypewhichcancontainanytypeofvariable.FreeBASICdoesnotprovidenativesupportforaByrefparameters:

Anycanbeusedinprocedureprototypes(inaDeclarestatement)withdeprecatedanditonlyexistsforcompatibilitywithQB.

Arraydimensions:Inarraydeclarations,AnycanbespecifiedinplaceofthearrayboundsinordertocreateadynamicarraywithacertainamountofdimensionsthatisdeterminedbasedonthenumberofAnysspecified(usethesyntaxwithAnyismandatorywhendeclaringadynamicarraymemberinsidea

Inparameterdeclarations,Anycanbealsospecifiedinsteadofemptyparenthesisinordertofixtheamountofdimensions.Initialization:

Anycanbeusedasafakeinitializertodisablethedefaultinitializationofvariablestoprogram'sresponsibilitytofillthevariableswithmeaningfuldatabeforereadingit.

ComparisontoC/C++:ThismatchesthebehaviorofavariabledeclarationwithoutinitializationvalueinC/C++.

SimilartoAnyinitializersforvariables,AnycanalsobeusedwiththeNewthatdonothaveconstructors).

Instr/InstrRev:AnycanbeusedwithInStrorInStrRevasaqualifierforthesubstring

Example

DeclareSubecho(ByValxAsAnyPtr)''echowillacceptanypointertype

DimAsIntegera(0To9)=Any''thisvariableisnotinitializedDimAsDoubled(0To4)

DimpAsAnyPtr

DimpaAsIntegerPtr=@a(0)Print"Notinitialized";echopa''passtoechoapointertointeger

DimpdAsDoublePtr=@d(0)Print"Initialized";echopd''passtoechoapointertodouble

p=pa''assigntopapointertointegerp=pd''assigntopapointertodouble

Sleep

Subecho(ByValxAsAnyPtr)DimAsIntegeriFori=0To39

'echointerpretsthedatainthepointerasbytesPrintCast(UBytePtr,x)[i]&"";NextPrintEndSub

'ExampleofANYdisablingthevariabletypecheckingDeclareSubecho(ByRefaAsAny)''ANYdisablesthecheckingforthetypeofdatapassedtothefunction

DimxAsSinglex=-15echox''Passingasingletoafunctionthatexpectsaninteger.Thecompilerdoesnotcomplain!!Sleep

Subecho(ByRefaAsInteger)PrintHex(a)EndSub

Dima(Any)AsInteger'1-dimensionaldynamicarrayDimb(Any,Any)AsInteger'2-dimensionaldynamicarrayDimc(Any,Any,Any)AsInteger'3-dimensionaldynamicarray'etc.

'FurtherRedimsorarrayaccessesmusthaveamatchingamountofdimensionsReDima(0To1)AsIntegerReDimb(1To10,2To5)AsIntegerReDimc(0To9,0To5,0To1)AsInteger

DialectDifferences

Notavailableinthe-langqbdialect.

DifferencesfromQB

PointersandinitializersarenewtoFreeBASIC.

Seealso

Dim

Declare

Append

Specifiestextfiletobeopenedforappendmode

SyntaxOpenfilenameforAppend[Encodingencoding_type][Locklock_type]as[#]filenum

Parametersfilenamefilenametoopenforappendencoding_typeindicatesencodingtypeforthefilelock_typelockingtobeusedwhilethefileisopenfilenumunusedfilenumbertoassociatewiththeopenfile

DescriptionAfilemodeusedwithOpentoopenatextfileforwriting.

ThismodeisusedtoaddtexttoanexistingfilewithPrint#,orcommaseparatedvalueswithWrite#.

Textfilescan'tbesimultaneouslyreadandwritteninFreeBASIC,soifbothfunctionsarerequiredonthesamefile,itmustbeopenedtwice.

filenamemustbeastringexpressionresultinginalegalfilenameinthetargetOS,withoutwildcards.Thefilewillbesoughtforinthepresentdirectory,unlessthefilenamecontainsapath.Ifthefiledoesnotexist,itiscreated.Thepointerissetafterthelastcharacterofthefile.

Encoding_typeindicatestheUnicodeEncodingofthefile,socharactersarecorrectlyread.Ifomitted,"ascii"encodingisdefaulted.Onlylittleendiancharacterencodingsaresupportedatthemoment.

"utf8"

"utf16"

"utf32"

"ascii"(thedefault)

Lock_typeindicatesthewaythefileislockedforotherprocesses,itisoneof:

Read-thefilecanbeopenedsimultaneouslybyotherprocesses,butnotforreadingWrite-thefilecanbeopenedsimultaneouslybyotherprocesses,butnotforwritingReadWrite-thefilecannotbeopenedsimultaneouslybyotherprocesses(thedefault)

filenumIsavalidFreeBASICfilenumber(intherange1..255)notbeingusedforanyotherfilepresentlyopen.Thefilenumberidentifiesthefilefortherestoffileoperations.AfreefilenumbercanbefoundusingtheFreeFilefunction.

Example

DimiAsIntegerFori=1To10Open"test.txt"ForAppendAs#1Print#1,"extendingtest.txt"Close#1Next

DifferencesfromQB

None

Seealso

Input(FileMode)

Open

Output

(Print|?)#

Write#

As

Optionalpartofadeclarationwhichspecifiesadatatype,orpartoftheOpenspecifiesafilehandle.

SyntaxsymbolnameAsdatatype

Open...As#filenumberType...Asdatatype

DescriptionAsisusedtodeclarethetypeofvariables,fieldsorargumentsandisalsousedinthestatementtodeterminethefilehandle.AsisalsousedwiththeType(Alias)toC'stypedefstatement.

Example

''don'ttrytocompilethiscode,theexamplesareunrelatedDeclareSubmySub(XAsInteger,YAsSing