printf（"less"）;
else
if（i>j）
printf（"greater"）;
else
if（i==j）
printf（"equal"）;
}
Answer:
less
10
Givetheoutputoftheprogram
voidmain（）
{
char*s="12345sn";
printf（"%d",sizeof（s））;
}
Answer:
4
11
Question:
Givetheoutputoftheprogram
voidmain（）
{
inti;
for（i=1;i<4,i++）
switch（i）
case1:
printf（"%d",i）;break;
{
case2:
printf（"%d",i）;break;
case3:
printf（"%d",i）;break;
}
switch（i）case4:
printf（"%d",i）;
}
Answer:
1,2,3,4
12.
Question:
Howtopasstwoargumentstoafunctionpromptedtobyfunctionpointer
A.g->（1,2）
B.*g（1,2）
C.（*g）（1,2）
D.g（1,2）
Answer:
C
13
Question:
Canyouhaveconstantvolatilevariable?
Answer:
YES.Wecanhaveaconstvolatilevariable.
avolatilevariableisavariablewhichcanbechangedbytheextrenalevents（likeaninterrputtimerswillincrementthevoltilevarible.Ifyoudontwantyouvolatilevaribaletobechangedthendeclarethemas“constvolatile”.
14.
Question:
studythecode:
#include
voidmain（）
{
constinta=100;
int*p;
p=&a;
（*p）++;
printf（"a=%d\n（*p）=%d\n",a,*p）;
}
Whatisprinted?
A）100,101B）100,100C）101,101D）Noneoftheabove
AnswerC
EmbeddedC
1.Usingthe#definestatement,howwouldyoudeclareamanifestconstantthatreturnsthenumberofsecondsinayear?
Disregardleapyearsinyouranswer.
Answer
#defineSECONDS_PER_YEAR（60*60*24*365）UL
I'mlookingforseveralthingshere:
Basicknowledgeofthe#definesyntax（forexample,nosemi-colonattheend,theneedtoparenthesize,andsoon）
Anunderstandingthatthepre-processorwillevaluateconstantexpressionsforyou.Thus,itisclearer,andpenalty-free,tospellouthowyouarecalculatingthenumberofsecondsinayear,ratherthanactuallydoingthecalculationyourself
Arealizationthattheexpressionwilloverflowanintegerargumentona16-bitmachine-hencetheneedfortheL,tellingthecompilertotreatthevariableasaLong
Asabonus,ifyoumodifiedtheexpressionwithaUL（indicatingunsignedlong）,thenyouareofftoagreatstart.Andremember,firstimpressionscount!
2.Writethe"standard"MINmacro-thatis,amacrothattakestwoargumentsandreturnsthesmallerofthetwoarguments.
Answer:
#defineMIN（A,B）（（A）<=（B）?
（A）:
（B））
Thepurposeofthisquestionistotestthefollowing:
Basicknowledgeofthe#definedirectiveasusedinmacros.ThisisimportantbecauseuntiltheinlineoperatorbecomespartofstandardC,macrosaretheonlyportablewayofgeneratinginlinecode.Inlinecodeisoftennecessaryinembeddedsystemsinordertoachievetherequiredperformancelevel
Knowledgeoftheternaryconditionaloperator.ThisoperatorexistsinCbecauseitallowsthecompilertoproducemoreoptimalcodethananif-then-elsesequence.Giventhatperformanceisnormallyanissueinembeddedsystems,knowledgeanduseofthisconstructisimportant
Understandingoftheneedtoverycarefullyparenthesizeargumentstomacros
Ialsousethisquestiontostartadiscussiononthesideeffectsofmacros,forexample,whathappenswhenyouwritecodesuchas:
least=MIN（*p++,b）;
3.Infiniteloopsoftenariseinembeddedsystems.HowdoesyoucodeaninfiniteloopinC?
Thereareseveralsolutionstothisquestion.Mypreferredsolutionis:
Answer:
while
（1）
{
?
}
5.Usingthevariablea,givedefinitionsforthefollowing:
a）Aninteger
b）Apointertoaninteger
c）Apointertoapointertoaninteger
d）Anarrayof10integers
e）Anarrayof10pointerstointegers
f）Apointertoanarrayof10integers
g）Apointertoafunctionthattakesanintegerasanargumentandreturnsaninteger
h）Anarrayoftenpointerstofunctionsthattakeanintegerargumentandreturnaninteger
Answers:
a）inta;//Aninteger
b）int*a;//Apointertoaninteger
c）int**a;//Apointertoapointertoaninteger
d）inta[10];//Anarrayof10integers
e）int*a[10];//Anarrayof10pointerstointegers
f）int（*a）[10];//Apointertoanarrayof10integers
g）int（*a）（int）;//Apointertoafunctionathattakesanintegerargumentandreturnsaninteger
h）int（*a[10]）（int）;//Anarrayof10pointerstofunctionsthattakeanintegerargumentandreturnaninteger
Peopleoftenclaimthatacoupleofthesearethesortsofthingthatonelooksupintextbooks-andIagree.Whilewritingthisarticle,Iconsultedtextbookstoensurethesyntaxwascorrect.However,Iexpecttobeaskedthisquestion（orsomethingclosetoit）whenI'mbeinginterviewed.Consequently,ImakesureIknowtheanswers,atleastforthefewhoursoftheinterview.Candidateswhodon'tknowalltheanswers（oratleastmostofthem）aresimplyunpreparedfortheinterview.Iftheycan'tbepreparedfortheinterview,whatwilltheybepreparedfor?
6.Whataretheusesofthekeywordstatic?
Answer:
StatichasthreedistinctusesinC:
Avariabledeclaredstaticwithinthebodyofafunctionmaintainsitsvaluebetweenfunctioninvocations
Avariabledeclaredstaticwithinamodule,（butoutsidethebodyofafunction）isaccessiblebyallfunctionswithinthatmodule.Itisnotaccessiblebyfunctionswithinanyothermodule.Thatis,itisalocalizedglobal
Functionsdeclaredstaticwithinamodulemayonlybecalledbyotherfunctionswithinthatmodule.Thatis,thescopeofthefunctionislocalizedtothemodulewithinwhichitisdeclared
Mostcandidatesgetthefirstpartcorrect.Areasonablenumbergetthesecondpartcorrect,whileapitifulnumberunderstandthethirdanswer.Thisisaseriousweaknessinacandidate,sinceheobviouslydoesn'tunderstandtheimportanceandbenefitsoflocalizingthescopeofbothdataandcode.
7.Whatdothefollowingdeclarationsmean?
constinta;
intconsta;
constint*a;
int*consta;
intconst*consta;
Answer
Thefirsttwomeanthesamething,namelyaisaconst（read-only）integer.Thethirdmeansaisapointertoaconstinteger（thatis,theintegerisn'tmodifiable,butthepointeris）.Thefourthdeclaresatobeaconstpointertoaninteger（thatis,theintegerpointedtobyaismodifiable,butthepointerisnot）.Thefinaldeclarationdeclaresatobeaconstpointertoaconstinteger（thatis,neithertheintegerpointedtobya,northepointeritselfmaybemodified）.
8.Whatdoesthekeywordvolatilemean?
Givethreedifferentexamplesofitsuse.
Answer:
Avolatilevariableisonethatcanchangeunexpectedly.Consequently,thecompilercanmakenoassumptionsaboutthevalueofthevariable.Inparticular,theoptimizermustbecarefultoreloadthevariableeverytimeitisusedinsteadofholdingacopyinaregister.Examplesofvolatilevariablesare:
Hardwareregistersinperipherals（forexample,statusregisters）
Non-automaticvariablesreferencedwithinaninterruptserviceroutine
Variablessharedbymultipletasksinamulti-threadedapplication
9.
Canapointerb
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