Top 100 C Interview Questions and Answers

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TOP 100
INTERVIEW QUESTIONS & ANSWERS
C

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WhoinventedCLanguage?
2
QUESTION
DennisRitchiein1972developedanewlanguagebyinheritingthefeaturesofbothBCPLandBandaddingadditionalfeatures.HenamedthelanguageasjustC
ANSWER
QUESTION 1

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WhatarethefeaturesofCLangauges?
3
QUESTION
•InConecanwriteprogramslikethatofhighlevellanguagesasinCOBOL,BASIC,FORTRANetc.aswellasitpermitsverycloseinteractionwiththeinnerworkingsofthecomputer.
•Itisageneralpurposeprogramminglanguage.Itisusuallycalledsystemprogramminglanguagebutequallysuitedtowritingavarietyofapplications.
•Itsupportsvariousdatatypes
•Itfollowstheprogrammingstylebasedonfundamentalcontrolflowconstructionsforstructuredprogramming
•Functionsmaybepre–definedoruserdefinedandtheymayreturnvaluesofbasictypes,structures,unionsorpointers
ANSWER
QUESTION 2

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Whataretheadvantagesofclanguage?
4
QUESTION
•Easytowrite
•Richsetofoperatorsandfunctionsthatarebuilt–in
•Supportforbit–wiseoperation
•Flexibleuseofpointers
•Directcontroloverthehardware
•AbilitytoaccessBIOS/DOSroutines
•InteractingusingInterrupts
•AbilitytowriteTSRprograms
•Abilitytocreate.COMfiles
•Abilitytocreatelibraryfiles(.LIB)
•Abilitytowriteinterfaceprograms
•IncorporatingassemblylanguageinCprogram
ANSWER
QUESTION 3

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Whatisaheaderfile?
5
QUESTION
Headerfilesprovidethedefinitionsanddeclarationsforthelibraryfunctions.Thus,eachheaderfilecontainsthelibraryfunctionsalongwiththenecessarydefinitionsanddeclarations.Forexample,stdio.h,math.h,stdlib.h, string.hetc.
ANSWER
QUESTION 4

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ListthedifferenttypesofCtokens?
6
QUESTION
•Constants
•Identifiers
•Keywords
•Operators
•Specialsymbols
•Strings
ANSWER
QUESTION 5

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Whatisaconstant?Whatarethedifferenttypesofconstants?
7
QUESTION
Aconstantisavaluethatdoesnotchangeduringtheprogramexecution.AconstantusedinCdoesnotoccupymemory.Therearefivetypesofconstants.Theyare:
•Integerconstants
•Floatingpointconstants
•Characterconstants
•Stringliterals
•Enumerationconstants
ANSWER
QUESTION 6

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Whatarethedifferenttypesofcinstructions?
8
QUESTION
•TherearebasicallythreetypesofinstructionsinCare:
•TypeDeclarationInstruction
•ArithmeticInstruction
•ControlInstruction
ANSWER
QUESTION 7

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WhyCiscalledamiddlelevellanguage?
9
QUESTION
CcombinesthefeaturesofbothAssemblyLevelLanguages(LowLevelLanguages)andHigherLevelLanguages. Forthisreason,CisreferredtoasaMiddleLevelLanguage.ThefeatureofALLsisthatofenablingustodevelopsystemlevelprogramsandthefeaturesofHLLsarethoseofhigherdegreeofreadabilityandmachine independence.
ANSWER
QUESTION 8

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Whatisthepurposeofmain()function?
10
QUESTION
•Thefunctionmain()invokesotherfunctionswithinit.Itisthefirstfunctiontobecalledwhentheprogramstartsexecution.
•Itisthestartingfunction.
•Itreturnsanintvaluetotheenvironmentthatcalledtheprogram.
•Recursivecallisallowedformain()also.
•Itisauser-definedfunction.
ANSWER
QUESTION 9

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Whatismeantbytypespecifiers?
11
QUESTION
Typespecifiersdecidetheamountofmemoryspaceoccupiedbyavariable.Intheeaseofintegraltypes;italsoexplicitlystatestherangeofvaluesthattheobjectcanhold.
ANSWER
QUESTION 10

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Whatisthedifferencebetweensinglecharaterconstantandstringconstant?
12
QUESTION
•Asinglecharacterconstantconsistsofonlyonecharacteranditisenclosedwithinapairofsinglequotes.
•Astringconstantconsistsofoneormorecharactersanditisenclosedwithinapairofdoublequotes.
ANSWER
QUESTION 11

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Whatisaloop?
13
QUESTION
Aloopisaprocesstodoajobrepeatedlywithpossiblydifferentdataeachtime.Thestatementsexecutedeachtimeconstitutetheloopbody,andeachpassiscallediteration.Aconditionmustbepresenttoterminatetheloop.
ANSWER
QUESTION 12

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Whatarethetypesofdatatypesandexplain?
14
QUESTION
TherearefivebasicDatatypesinC.Theseare:
•void:meansnothingi.e.nodatainvolvementinanaction
•char:toworkwithalltypesofcharactersusedincomputeroperations
•int:toworkwithanintegertypeofdatainanycomputationalwork
•float:toworkwiththerealtypeofdataorscientificnumbersintheexponentialform
•double:toworkwithdoubleprecisionofnumberswhentheapproximationisverycrucial.
ANSWER
QUESTION 13

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WhatisthegeneralformofaCprogram?
15
QUESTION
ACprogrambeginswiththepreprocessordirectives,inwhichtheprogrammerwouldspecifywhichheaderfileandwhatconstants(ifany)tobeused.Thisisfollowedbythemainfunctionheading.Withinthemainfunctionliesthevariabledeclarationandprogramstatement.
ANSWER
QUESTION 14

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WhatisthedifferencebetweenCallbyValueandCallbyReference?
16
QUESTION
WhenusingCallbyValue,youaresendingthevalueofavariableasparametertoafunction,whereasCallbyReferencesendstheaddressofthevariable.Also,underCallbyValue,thevalueintheparameterisnotaffectedbywhateveroperationthattakesplace,whileinthecaseofCallbyReference,valuescanbeaffectedbytheprocesswithinthefunction.
ANSWER
QUESTION 15

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Whatisastack?
17
QUESTION
Astackisoneformofadatastructure.DataisstoredinstacksusingtheFILO(FirstInLastOut)approach.Atanyparticularinstance,onlythetopofthestackisaccessible,whichmeansthatinordertoretrievedatathatisstoredinsidethestack,thoseontheupperpartshouldbeextractedfirst.StoringdatainastackisalsoreferredtoasaPUSH,whiledataretrievalisreferredtoasaPOP.
ANSWER
QUESTION 16

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Whatistheuseofa„0′character?
18
QUESTION
Itisreferredtoasaterminatingnullcharacter,andisusedprimarilytoshowtheendofastringvalue.
ANSWER
QUESTION 17

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Whatisthedifferencebetweenthe=symboland==symbol?
19
QUESTION
The=symbolisoftenusedinmathematicaloperations.Itisusedtoassignavaluetoagivenvariable.Ontheotherhand,the==symbol,alsoknownas“equalto”or“equivalentto”,isarelationaloperatorthatisusedtocomparetwovalues
ANSWER
QUESTION 18

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Whatisthemodulusoperator?
20
QUESTION
Themodulusoperatoroutputstheremainderofadivision.Itmakesuseofthepercentage(%)symbol.Forexample: 10%3=1,meaningwhenyoudivide10by3,theremainderis1.
ANSWER
QUESTION 19

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Whichofthefollowingoperatorsisincorrectandwhy?(>=,<=,<>,==)
21
QUESTION
<>isincorrect.Whilethisoperatoriscorrectlyinterpretedas“notequalto”inwritingconditionalstatements,itisnottheproperoperatortobeusedinCprogramming.Instead,theoperator!=mustbeusedtoindicate“notequalto”condition.
ANSWER
QUESTION 20

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Whatissyntaxerror?
22
QUESTION
Syntaxerrorsareassociatedwithmistakesintheuseofaprogramminglanguage.Itmaybeacommandthatwasmisspelledoracommandthatmustwasenteredinlowercasemodebutwasinsteadenteredwithanuppercasecharacter.Amisplacedsymbol,orlackofsymbol,somewherewithinalineofcodecanalsoleadtosyntaxerror.
ANSWER
QUESTION 21

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CanIuse“int”datatypetostorethevalue32768?Why?
23
QUESTION
No.“int”datatypeiscapableofstoringvaluesfrom-32768to32767.Tostore32768,youcanuse“longint”instead. Youcanalsouse“unsignedint”,assumingyoudon‟tintendtostorenegativevalues.
ANSWER
QUESTION 22

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Whenisthe“void”keywordusedinafunction?
24
QUESTION
Whendeclaringfunctions,youwilldecidewhetherthatfunctionwouldbereturningavalueornot.Ifthatfunctionwillnotreturnavalue,suchaswhenthepurposeofafunctionistodisplaysomeoutputsonthescreen,then“void”istobeplacedattheleftmostpartofthefunctionheader.Whenareturnvalueisexpectedafterthefunctionexecution,thedatatypeofthereturnvalueisplacedinsteadof“void”.
ANSWER
QUESTION 23

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WhatisthesignificanceofanalgorithmtoCprogramming?
25
QUESTION
Beforeaprogramcanbewritten,analgorithmhastobecreatedfirst.Analgorithmprovidesastepbystepprocedureonhowasolutioncanbederived.Italsoactsasablueprintonhowaprogramwillstartandend, includingwhatprocessandcomputationsareinvolved.
ANSWER
QUESTION 24

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HowdoyougeneraterandomnumbersinC?
26
QUESTION
RandomnumbersaregeneratedinCusingtherand()command.Forexample:anyNum=rand()willgenerateanyintegernumberbeginningfrom0,assumingthatanyNumisavariableoftypeinteger.
ANSWER
QUESTION 25

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Whatisdebugging?
27
QUESTION
Debuggingistheprocessofidentifyingerrorswithinaprogram.Duringprogramcompilation,errorsthatarefoundwillstoptheprogramfromexecutingcompletely.Atthisstate,theprogrammerwouldlookintothepossibleportionswheretheerroroccurred.Debuggingensurestheremovaloferrors,andplaysanimportantroleinensuringthattheexpectedprogramoutputismet.
ANSWER
QUESTION 26

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Whatdoesthe&&operatordoinaprogramcode?
28
QUESTION
The&&isalsoreferredtoasANDoperator.Whenusingthisoperator,allconditionsspecifiedmustbeTRUEbeforethenextactioncanbeperformed.Ifyouhave10conditionsandallbut1failstoevaluateasTRUE,theentireconditionstatementisalreadyevaluatedasFALSE.
ANSWER
QUESTION 27

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Whatis||operatorandhowdoesitfunctioninaprogram?
29
QUESTION
The||isalsoknownastheORoperatorinCprogramming.Whenusing||toevaluatelogicalconditions,anyconditionthatevaluatestoTRUEwillrendertheentireconditionstatementasTRUE.
ANSWER
QUESTION 28

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Whatwillbetheoutcomeofthefollowingconditionalstatementifthevalueofvariablesis10?s>=10&&s<25&&s!=12
30
QUESTION
TheoutcomewillbeTRUE.Sincethevalueofsis10,s>=10evaluatestoTRUEbecausesisnotgreaterthan10butisstillequalto10.s<25isalsoTRUEsince10islessthen25.Justthesame,s!=12,whichmeanssisnotequalto12,evaluatestoTRUE.The&&istheANDoperator,andfollowstherulethatifallindividualconditionsareTRUE,theentirestatementisTRUE.
ANSWER
QUESTION 29

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WhatisFIFO?
31
QUESTION
InCprogramming,thereisadatastructureknownasqueue.Inthisstructure,dataisstoredandaccessedusingFIFOformat,orFirst-In-First-Out.Aqueuerepresentsalinewhereinthefirstdatathatwasstoredwillbethefirstonethatisaccessibleaswell.
ANSWER
QUESTION 30

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InClanguage,thevariablesNAME,name,andNameareallthesame.TRUEorFALSE?
32
QUESTION
FALSE.Clanguageisacasesensitivelanguage.Therefore,NAME,nameandNamearethreeuniquelydifferentvariables.
ANSWER
QUESTION 31

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Whenisa“switch”statementpreferableoveran“if”statement?
33
QUESTION
Theswitchstatementisbestusedwhendealingwithselectionsbasedonasinglevariableorexpression.However, switchstatementscanonlyevaluateintegerandcharacterdatatypes.
ANSWER
QUESTION 32

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Whatisgets()function?
34
QUESTION
Thegets()functionallowsafulllinedataentryfromtheuser.Whentheuserpressestheenterkeytoendtheinput, theentirelineofcharactersisstoredtoastringvariable.Notethattheenterkeyisnotincludedinthevariable,butinsteadanullterminator0isplacedafterthelastcharacter.
ANSWER
QUESTION 33

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DifferencebetweenSyntaxandlogicalerror?
35
QUESTION
Syntaxerror:
Theseinvolvesvalidationofsyntaxoflanguage
Compilerprintsdiagnosticmessage.
Logicalerror:
Logicalerrorarecausedbyanincorrectalgorithmorbyastatementmistypedinsuchawaythatitdoesn‟tvioletsyntaxoflanguage.
Itisdifficulttofind.
ANSWER
QUESTION 34

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Whatisstaticmemoryallocation?
36
QUESTION
Compilerallocatesmemoryspaceforadeclaredvariable.Byusingtheaddressofoperator,thereservedaddressisobtainedandthisaddressisassignedtoapointervariable.Thiswayofassigningpointervaluetoapointervariableatcompilationtimeisknownasstaticmemoryallocation.
ANSWER
QUESTION 35

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Whatisdynamicmemoryallocation?
37
QUESTION
Adynamicmemoryallocationusesfunctionssuchasmalloc()orcalloc()togetmemorydynamically.Ifthesefunctionsareusedtogetmemorydynamicallyandthevaluesreturnedbythesefunctionareassignedtopointervariables,suchawayofallocatingmemoryatruntimeisknownasdynamicmemoryallocation.
ANSWER
QUESTION 36

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ArePointersInteger?
38
QUESTION
No,Pointersarenotintegers.Apointerisanaddress.Itisapositivenumber.
ANSWER
QUESTION 37

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Inheaderfileswhetherfunctionsaredeclaredordefined?
39
QUESTION
Functionsaredeclaredwithinheaderfile.Thatisfunctionprototypesexistinaheaderfile,notfunctionbodies.Theyaredefinedinlibrary(lib).
ANSWER
QUESTION 38

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Differencebetweenstrdupandstrcpy?
40
QUESTION
Bothcopyastring.Strcpywantsabuffertocopyinto.Strdupallocatesabufferusingmalloc().Unlikestrcpy(), strdup()isnotspecifiedbyANSI.
ANSWER
QUESTION 39

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Whatisspaghettiprogramming?
41
QUESTION
Spaghettiprogrammingreferstocodesthattendtogettangledandoverlappedthroughouttheprogram.Thisunstructuredapproachtocodingisusuallyattributedtolackofexperienceonthepartoftheprogrammer. Spaghettiprogramingmakesaprogramcomplexandanalyzingthecodesdifficult,andsomustbeavoidedasmuchaspossible.
ANSWER
QUESTION 40

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InCprogramming,howdoyouinsertquotecharacters(„and“)intotheoutputscreen?
42
QUESTION
Thisisacommonproblemforbeginnersbecausequotesarenormallypartofaprintfstatement.Toinsertthequotecharacteraspartoftheoutput,usetheformatspecifiers‟(forsinglequote),and”(fordoublequote).
ANSWER
QUESTION 41

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Whatisanestedloop?
43
QUESTION
Anestedloopisaloopthatrunswithinanotherloop.Putitinanothersense,youhaveaninnerloopthatisinsideanouterloop.Inthisscenario,theinnerloopisperformedanumberoftimesasspecifiedbytheouterloop.Foreachturnontheouterloop,theinnerloopisfirstperformed.
ANSWER
QUESTION 42

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Canthecurlybrackets{}beusedtoencloseasinglelineofcode?
44
QUESTION
Whilecurlybracketsaremainlyusedtogroupseverallinesofcodes,itwillstillworkwithouterrorifyouuseditforasingleline.Someprogrammerspreferthismethodasawayoforganizingcodestomakeitlookclearer,especiallyinconditionalstatements.
ANSWER
QUESTION 43

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Whatarecompoundstatements?
45
QUESTION
Compoundstatementsaremadeupoftwoormoreprogramstatementsthatareexecutedtogether.ThisusuallyoccurswhilehandlingconditionswhereinaseriesofstatementsareexecutedwhenaTRUEorFALSEisevaluated.Compoundstatementscanalsobeexecutedwithinaloop.Curlybrackets{}areplacedbeforeandaftercompoundstatements.
ANSWER
QUESTION 44

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Whatisaregistervariable?
46
QUESTION
RegistervariablesarestoredintheCPUregisters.Itsdefaultvalueisagarbagevalue.Scopeofaregistervariableislocaltotheblockinwhichitisdefined.Lifetimeistillcontrolremainswithintheblockinwhichtheregistervariableisdefined.VariablestoredinaCPUregistercanalwaysbeaccessedfasterthantheonethatisstoredinmemory.Therefore,ifavariableisusedatmanyplacesinaprogram,itisbettertodeclareitsstorageclassasregister
Example:registerintx=5;
Variablesforloopcounterscanbedeclaredasregister.Notethatregisterkeywordmaybeignoredbysomecompilers.
ANSWER
QUESTION 45

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Whatissizeofvoidpointer?
47
QUESTION
Sizeofanytypeofpointerincisindependentofdatatypewhichispointerispointingi.e.sizeofalltypeofpointer(near)incistwobyteeitheritischarpointer,doublepointer,functionpointerornullpointer.Voidpointerisnotexceptionofthisruleandsizeofvoidpointerisalsotwobyte.
ANSWER
QUESTION 46

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Whatareprintfandscanf,callbyreferenceorcallbyvalue?
48
QUESTION
Printf:Callbyvalue
Scanf:Callbyreference
ANSWER
QUESTION 47

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Whatisaconstpointer?
49
QUESTION
aconstpointermeansthepointerwhichrepresentstheaddressofonevalue.soifyoudeclareapointerinsidethefunction,itdoesn'thavescopeoutsidethefunction.ifitisalsoavailabletotheoutsidefunctionwheneverwedeclareapointerasconst.
ANSWER
QUESTION 48

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Whydoesn++executemuchfasterthann+1?
50
QUESTION
n++takesmorethanoneinstruction,++nisfaster.n++hastostoren,incrementthevariableandreturnn,while++nincrementnandreturnwithoutstoringthepreviousvalueofn.
ANSWER
QUESTION 49

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WhatismodularProgramming?
51
QUESTION
Ifaprogramislarge,itissubdividedintoanumberofsmallerprogramsthatarecalledmodulesorsubprograms.Ifacomplexproblemissolvedusingmoremodules,thisapproachisknownasmodularprogramming.
ANSWER
QUESTION 51

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Whydoesn'tCsupportfunctionoverloading?
52
QUESTION
OverloadingispolymorphismwhichisoneofthecharacteristicsofObjectorientedprogramming.CisnotandobjectorientedlanguagelikeC++orJava.Therefore,nooverloading,inheritance,etc.
ANSWER
QUESTION 51

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Whatisanincompletetype?
53
QUESTION
Incompletetypesreferstopointersinwhichthereisnonavailabilityoftheimplementationofthereferencedlocationoritpointstosomelocationwhosevalueisnotavailableformodification.
ANSWER
QUESTION 52

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ExplaintheDifferencebetweenCandC++?
54
QUESTION
CisthepredecessorofC++.C++isanObjectOriented,non-procedurallanguage,unlikeC,whichisaprocedurallanguage.C++treatsalldataandfunctionalhandlingintermsofObjectsandtheirrelationships.
ANSWER
QUESTION 53

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WhatisNestinginC?
55
QUESTION
Includingoneconstructedinsideanother,isnesting.Nestingcanbeastructureinsideanotherstructure,anif-elsestatementwithinanother,multiplewhileloops,oneinsidetheother.Continuingourearlierexample,ifyouhaveacollectionofbikes,insteadofgroupingthemseparately,youcannestthemwithinamainstructure,whichyoucanname“CollectionofBikes”.
ANSWER
QUESTION 54

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Howiscalloc()differentfrommalloc()?
56
QUESTION
Themaindifferencebetweenthetwoisthatcalloc(),whenitisusedtoassignablockofmemory,theallocatedcontentsareinitializedto0.Malloc(),ontheotherhand,doesnotinitialisethememoryblockitassigns.Thememoryjusthasrandomvaluesleftoverfromprevioususage.
ANSWER
QUESTION 55

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WhatareDestructorsinCLanguage?
57
QUESTION
Classifyingadestructoryoucancallitaclassobjectanditiscalledadestructoronceitgoesoutofscopeorgetsdeletedovertly.Thejobofadestructoristoputanendtoobjectsbeingproducedbyaconstructor.Justliketheconstructoryoucanconsiderdestructorafunctionalmemberanditisspecificallyknownbyaclassname.
ANSWER
QUESTION 56

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Whataretheusesofapointer?
58
QUESTION
Pointerisusedinthefollowingcases
i)Itisusedtoaccessarrayelements
ii)Itisusedfordynamicmemoryallocation.
iii)ItisusedinCallbyreference
iv)Itisusedindatastructuresliketrees,graph,linkedlistetc.
ANSWER
QUESTION 57

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Whatisaunion?
59
QUESTION
Unionisacollectionofheterogeneousdatatypebutitusesefficientmemoryutilizationtechniquebyallocatingenoughmemorytoholdthelargestmember.Hereasingleareaofmemorycontainsvaluesofdifferenttypesatdifferenttime.Aunioncanneverbeinitialized.
ANSWER
QUESTION 58

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Whataremacros?Whatareitsadvantagesanddisadvantages?
60
QUESTION
Macrosareabbreviationsforlengthyandfrequentlyusedstatements.Whenamacroiscalledtheentirecodeissubstitutedbyasinglelinethoughthemacrodefinitionisofseverallines.
Theadvantageofmacroisthatitreducesthetimetakenforcontroltransferasincaseoffunction.
Thedisadvantageofitisheretheentirecodeissubstitutedsotheprogrambecomeslengthyifamacroiscalledseveraltimes.
ANSWER
QUESTION 59

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Whatareenumerations?
61
QUESTION
Theyarealistofnamedinteger-valuedconstants.Example:enumcolor{black,orange=4,yellow,green,blue, violet};Thisdeclarationdefinesthesymbols“black”,“orange”,“yellow”,etc.tohavethevalues“1,”“4,”“5,”…etc. Thedifferencebetweenanenumerationandamacroisthattheenumactuallydeclaresatype,andthereforecanbetypechecked.
ANSWER
QUESTION 60

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Whatistheuseoftypedef?
62
QUESTION
Thetypedefhelpineasiermodificationwhentheprogramsareportedtoanothermachine.Adescriptivenewnamegiventotheexistingdatatypemaybeeasiertounderstandthecode.
ANSWER
QUESTION 61

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WhatisthedifferencebetweenStringsandArrays?
63
QUESTION
StringisasequenceofcharactersendingwithNULL.itcanbetreatedasaonedimensionalarrayofcharactersterminatedbyaNULLcharacter.
ANSWER
QUESTION 62

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Whatisanormalizedpointer,howdowenormalizeapointer?
64
QUESTION
Itisa32bitpointer,whichhasasmuchofitsvalueinthesegmentregisteredaspossible.Sinceasegmentcanstartevery16bytessotheoffsetwillhaveavaluefrom0toF.fornormalizationconverttheaddressinto20bitaddressthenusethe16bitforsegmentaddressand4bitfortheoffsetaddress.Givenapointer500D:9407,weconvertittoa20bitabsoluteaddress549D7,Whichthennormalizedto549D:0007.
ANSWER
QUESTION 63

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WhatisgenericpointerinC?
65
QUESTION
InCvoid*actsasagenericpointer.Whenotherpointertypesareassignedtogenericpointer,conversionsareappliedautomatically(implicitconversion).
ANSWER
QUESTION 64

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Differencebetweenlinkerandlinkage?
66
QUESTION
Linkerconvertsanobjectcodeintoanexecutablecodebylinkingtogetherthenecessarybuiltinfunctions.Theformandplaceofdeclarationwherethevariableisdeclaredinaprogramdeterminethelinkageofvariable.
ANSWER
QUESTION 65

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Whatisafunction?
67
QUESTION
Alargeprogramissubdividedintoanumberofsmallerprogramsorsubprograms.Eachsubprogramspecifiesoneormoreactionstobeperformedforthelargerprogram.Suchsubprogramsarecalledfunctions.
ANSWER
QUESTION 66

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Whatisanargument?
68
QUESTION
Anargumentisanentityusedtopassdatafromthecallingtoacalledfunction.
ANSWER
QUESTION 67

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WriteaprogramwhichemploysRecursion?
69
QUESTION
intfact(intn){returnn>1?n*fact(n–1):1;}
ANSWER
QUESTION 68

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Whatdothe„c‟and„v‟inargcandargvstandfor?
70
QUESTION
Thecinargc(argumentcount)standsforthenumberofcommandlineargumenttheprogramisinvokedwithandvinargv(argumentvector)isapointertoanarrayofcharacterstringthatcontainthearguments.
ANSWER
QUESTION 69

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WhatareCidentifiers?
71
QUESTION
Thesearenamesgiventovariousprogrammingelementsuchasvariables,function,arrays.Itisacombinationofletter,digitandunderscore.Itshouldbeginwithletter.Backspaceisnotallowed.
ANSWER
QUESTION 70

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Whatdothefunctionsatoi(),itoa()andgcvt()do?
72
QUESTION
atoi()isamacrothatconvertsintegertocharacter.
itoa()Itconvertsanintegertostring
gcvt()Itconvertsafloatingpointnumbertostring
ANSWER
QUESTION 71

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Howisfopen()used?
73
QUESTION
Thefunctionfopen()returnsafilepointer.Henceafilepointerisdeclaredanditisassignedas
FILE*fp;
fp=fopen(filename,mode);
filenameisastringrepresentingthenameofthefileandthemoderepresents:
“r”forreadoperation
“w”forwriteoperation
“a”forappendoperation
“r+”,”w+”,”a+”forupdateoperation
ANSWER
QUESTION 72

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Whatisthepurposeofftell?
74
QUESTION
Thefunctionftell()isusedtogetthecurrentfilerepresentedbythefilepointer.
ftell(fp);
returnsalongintegervaluerepresentingthecurrentfilepositionofthefilepointedbythe
filepointerfp.Ifanerroroccurs,-1isreturned.
ANSWER
QUESTION 73

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Discussonpointerarithmetic?
75
QUESTION
1.Assignmentofpointerstothesametypeofpointers.
2.Addingorsubtractingapointerandaninteger.
3.Subtractingorcomparingtwopointer.
4.Incrementingordecrementingthepointerspointingtotheelementsofanarray.Whenapointertoanintegerisincrementedbyone,theaddressisincrementedbytwo.Itisdoneautomaticallybythecompiler.
5.Assigningthevalue0tothepointervariableandcomparing0withthepointer.Thepointerhavingaddress0pointstonowhereatall.
ANSWER
QUESTION 74

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Whatistheinvalidpointerarithmetic?
76
QUESTION
i)adding,multiplyinganddividingtwopointers.
ii)Shiftingormaskingpointer.
iii)Additionoffloatordoubletopointer.
iv)Assignmentofapointerofonetypetoapointerofanothertype?
ANSWER
QUESTION 75

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Canweinitializeunions?
77QUESTION
ANSIStandardCallowsaninitializerforthefirstmemberofaunion.Thereisnostandardwayofinitializinganyothermember(nor,underapre-ANSIcompiler,istheregenerallyanywayofinitializingaunionatall).
ANSWER
QUESTION 76

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WhatisOutputoffollowingcsnippet?
intmain(){
char*s="Abhas";
printf("%s",s+2);
getch();
}
78
QUESTION
Has.Explanation:Intheaboveprogramroleof%sistodisplaythestringwhoseaddressispassedasanargument.Thisishowastandardprintfstatementworksinclanguage.Nowsincewehavepasseds+2asanargumentthereforefirstvalueofthisexpressionisevaluated.Here„s‟wouldrefertoaddressoffirstcharacterinstring„s‟.Nowprintfwouldgetaddressofthirdcharacter(addressoffirstcharacter+2)asargumentsoitwilldisplaythestringstartingfromthirdposition.Henceoutputwouldbe„has‟.
ANSWER
QUESTION 77

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Whatisdifferencebetween.comprogramand.exeprogram?
79
QUESTION
Both.comand.exeprogramareexecutableprogrambut.comprogramexecutesfasterthan.exeprogram.Alldriversare.comprogram..comfilehashigherpreferencethan.exe.
ANSWER
QUESTION 78

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DescribeturbocCompiler?
80
QUESTION
TurbocisanIDEprogramminglanguagecreatedbyBorland.TurboC3.0isbasedonMSDOSoperationsystem.Itisoneofthemostpopularccompilers.Ituses8086microprocessorwhichis16bitmicroprocessor.Ithas20addressbusesand16databus.Itswordlengthistwobyte.
ANSWER
QUESTION 79

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Outoffgets()andgets()whichfunctionissafetouseandwhy?
81
QUESTION
Fgets()issaferthangets(),becausewecanspecifyamaximuminputlength.Neitheroneiscompletelysafe, becausethecompilercan‟tprovethatprogrammerwon‟toverflowthebufferhepasstofgets().
ANSWER
QUESTION 80

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Differentiatebetweena“forloop”anda“whileloop”?
82
QUESTION
Forexecutingasetofstatementsfixednumberoftimesweuse“forloop”whilewhenthenumberofiterationstobeperformedisnotknowninadvanceweuse“whileloop”.
ANSWER
QUESTION 81

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Isthereabuilt-infunctioninCthatcanbeusedforsortingdata?
83
QUESTION
Yes,usetheqsort()function.Itisalsopossibletocreateuserdefinedfunctionsforsorting,suchasthosebasedontheballoonsortandbubblesortalgorithm.
ANSWER
QUESTION 82

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Whataretheadvantagesanddisadvantagesofaheap?
84
QUESTION
Storingdataontheheapisslowerthanitwouldtakewhenusingthestack.However,themainadvantageofusingtheheapisitsflexibility.That‟sbecausememoryinthisstructurecanbeallocatedandremoveinanyparticularorder.Slownessintheheapcanbecompensatedifanalgorithmwaswelldesignedandimplemented.
ANSWER
QUESTION 83

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HowdoyouconvertstringstonumbersinC?
85
QUESTION
Youcanwriteyouownfunctionstodostringtonumberconversions,orinsteaduseC‟sbuiltinfunctions.Youcanuseatoftoconverttoafloatingpointvalue,atoitoconverttoanintegervalue,andatoltoconverttoalongintegervalue.
ANSWER
QUESTION 84

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Createasimplecodefragmentthatwillswapthevaluesoftwovariablesnum1andnum2.
86
QUESTION
inttemp;
temp=num1;
num1=num2;
num2=temp;
ANSWER
QUESTION 85

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Whatistheuseofasemicolon(;)attheendofeveryprogramstatement?
87
QUESTION
Ithastodowiththeparsingprocessandcompilationofthecode.Asemicolonactsasadelimiter,sothatthecompilerknowswhereeachstatementends,andcanproceedtodividethestatementintosmallerelementsforsyntaxchecking.
ANSWER
QUESTION 86

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Whatdoesthecharacters“r”and“w”meanwhenwritingprogramsthatwillmakeuseoffiles?
88
QUESTION
“r”means“read”andwillopenafileasinputwhereindataistoberetrieved.“w”means“write”,andwillopenafileforoutput.Previousdatathatwasstoredonthatfilewillbeerased.
ANSWER
QUESTION 87

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WhichfunctioninCcanbeusedtoappendastringtoanotherstring?
89
QUESTION
Thestrcatfunction.Ittakestwoparameters,thesourcestringandthestringvaluetobeappendedtothesourcestring.
ANSWER
QUESTION 88

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Whatisthedifferencebetweenfunctionsgetch()andgetche()?
90
QUESTION
Bothfunctionswillacceptacharacterinputvaluefromtheuser.Whenusinggetch(),thekeythatwaspressedwillnotappearonthescreen,andisautomaticallycapturedandassignedtoavariable.Whenusinggetche(),thekeythatwaspressedbytheuserwillappearonthescreen,whileatthesametimebeingassignedtoavariable.
ANSWER
QUESTION 89

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Whatdoesthefunctiontoupper()do?
91
QUESTION
Itisusedtoconvertanylettertoitsuppercasemode.Toupper()functionprototypeisdeclaredin<ctype.h>.Notethatthisfunctionwillonlyconvertasinglecharacter,andnotanentirestring.
ANSWER
QUESTION 90

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Whatarerun-timeerrors?
92
QUESTION
Theseareerrorsthatoccurwhiletheprogramisbeingexecuted.Onecommoninstancewhereinrun-timeerrorscanhappeniswhenyouaretryingtodivideanumberbyzero.Whenrun-timeerrorsoccur,programexecutionwillpause,showingwhichprogramlinecausedtheerror.
ANSWER
QUESTION 91

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Isthisprogramstatementvalid?INT=10.50;
93
QUESTION
AssumingthatINTisavariableoftypefloat,thisstatementisvalid.OnemaythinkthatINTisareservedwordandmustnotbeusedforotherpurposes.However,recallthatreservedwordsareexpressinlowercase,sotheCcompilerwillnotinterpretthisasareservedword.
ANSWER
QUESTION 92

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Whatiswrongwiththisprogramstatement?void=10;
94
QUESTION
ThewordvoidisareservedwordinClanguage.Youcannotusereservedwordsasauser-definedvariable.
ANSWER
QUESTION 93

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WhatwouldhappentoXinthisexpression:X+=15;(assumingthevalueofXis5)
95
QUESTION
X+=15isashortmethodofwritingX=X+15,soiftheinitialvalueofXis5,then5+15=20.
ANSWER
QUESTION 94

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Notallreservedwordsarewritteninlowercase.TRUEorFALSE?
96
QUESTION
FALSE.Allreservedwordsmustbewritteninlowercase;otherwisetheCcompilerwouldinterpretthisasunidentifiedandinvalid.
ANSWER
QUESTION 95

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Whatisfloatingpointconstants?
97
QUESTION
Floating-pointconstantsarenumberswithdecimalparts.Afloating-pointconstantsconsistsof:
Anintegralpart
Adecimalpoint
Afractionalpart
Anexponentpart
Anoptionalsuffix
ANSWER
QUESTION 96

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Whatisthedifferencebetweenfreadandfwritefunction?
98
QUESTION
Thefread()functionreturnsthenumberofitemsread.Thisvaluemaybelessthancountiftheendofthefileisreachedoranerroroccurs.Thefwrite()functionreturnsthenumberofitemswritten.Thisvaluewillequalcountunlessanerroroccurs.
ANSWER
QUESTION 97

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Whatismeantbyinheritance?
99QUESTION
Inheritanceistheprocessbywhichobjectsofoneclassacquirepropertiesofobjectsofanotherclass.
ANSWER
QUESTION 98

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WhatisaternaryoperatorinC?
100
QUESTION
PerhapsthemostunusualoperatorinClanguageisonecalledtheconditionalexpressionoperator.UnlikeallotheroperatorsinCwhichareeitherunaryorbinaryoperatorstheconditionalexpressionoperatorisaternaryoperator; thatis,ittakesthreeoperands.Thetwosymbolsthatareusedtodenotethisoperatorarethequestionmark(?) andthecolon(:).Thefirstoperandisplacedbeforethe?,thesecondbetweenthe?andtheandthethirdafterthe:.
ANSWER
QUESTION 99

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Whatisunaryoperator?
101
QUESTION
Theoperatorsthatactuponasingleoperandtoproduceanewvalueareknownasunaryoperators.
ANSWER
QUESTION 100

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Resources
102
http://www.fresherventure.net/frequently-asked-c-language-interview-questions- and-answers/
http://www.itechaleart.com/2014/06/top-100-c-interview-qa.html
http://placement.freshersworld.com/power-preparation/technical-interview- questions/C-programming-answers-21419
http://career.guru99.com/top-100-c-interview-questions-answers/
http://www.slideshare.net/vineetkumarsaini/top-c-language-interview-questions- and-answer
http://www.cquestions.com/2010/10/c-interview-questions-and-answers.html
http://placementsindia.blogspot.com/2007/10/basic-c-interview-questions.html
https://www.udemy.com/blog/c-programming-questions/
http://crackaninterview.com/c-language-interview-questions/
http://www.cwithabhas.com/2013/09/simple-c-interview-questions-for-mass.html
http://www.freejobalert.com/c-interview-questions/2891/

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