A char array is just that - an array of characters: ... A string is a class that contains a char array, but automatically manages it for you. Most ...
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Differencebetweenstringandchar[]typesinC++
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12years,10monthsago
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2years,1monthago
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IknowalittleCandnowI'mtakingalookatC++.
I'musedtochararraysfordealingwithCstrings,butwhileIlookatC++codeIseethereareexamplesusingbothstringtypeandchararrays:
#include
#include
usingnamespacestd;
intmain(){
stringmystr;
cout<
usingnamespacestd;
intmain(){
charname[256],title[256];
cout<yougettwoheaps->memorycannotbefreed,assertionerrorsindebugmodeiflibfoomodifiesthestringreferenceandhandsanstd::stringwithanewpointerback.
– Cygon
Aug21,2009at20:27
2
I'mjustgoingtostickwith"Inshort:useC++stringsinallyourinternalfunctionsandmethods."TryingtounderstandyourExamplesmaidmybrainpop.
– Stephen
Oct29,2010at15:51
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17
Arkaitziscorrectthatstringisamanagedtype.Whatthismeansforyouisthatyouneverhavetoworryabouthowlongthestringis,nordoyouhavetoworryaboutfreeingorreallocatingthememoryofthestring.
Ontheotherhand,thechar[]notationinthecaseabovehasrestrictedthecharacterbuffertoexactly256characters.Ifyoutriedtowritemorethan256charactersintothatbuffer,atbestyouwilloverwriteothermemorythatyourprogram"owns".Atworst,youwilltrytooverwritememorythatyoudonotown,andyourOSwillkillyourprogramonthespot.
Bottomline?Stringsarealotmoreprogrammerfriendly,char[]sarealotmoreefficientforthecomputer.
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answeredAug17,2009at11:00
MarkRushakoffMarkRushakoff
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Atworst,otherpeoplewilloverwritememoryandrunmaliciouscodeonyourcomputer.Seealsobufferoverflow.
– DavidJohnstone
Mar18,2010at1:12
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Well,stringtypeisacompletelymanagedclassforcharacterstrings,whilechar[]isstillwhatitwasinC,abytearrayrepresentingacharacterstringforyou.
IntermsofAPIandstandardlibraryeverythingisimplementedintermsofstringsandnotchar[],buttherearestilllotsoffunctionsfromthelibcthatreceivechar[]soyoumayneedtouseitforthose,apartfromthatIwouldalwaysusestd::string.
Intermsofefficiencyofcoursearawbufferofunmanagedmemorywillalmostalwaysbefasterforlotsofthings,buttakeinaccountcomparingstringsforexample,std::stringhasalwaysthesizetocheckitfirst,whilewithchar[]youneedtocomparecharacterbycharacter.
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answeredAug17,2009at10:54
ArkaitzJimenezArkaitzJimenez
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Ipersonallydonotseeanyreasonwhyonewouldliketousechar*orchar[]exceptforcompatibilitywitholdcode.std::string'snoslowerthanusingac-string,exceptthatitwillhandlere-allocationforyou.Youcansetit'ssizewhenyoucreateit,andthusavoidre-allocationifyouwant.It'sindexingoperator([])providesconstanttimeaccess(andisineverysenseofthewordtheexactsamethingasusingac-stringindexer).Usingtheatmethodgivesyouboundscheckedsafetyaswell,somethingyoudon'tgetwithc-strings,unlessyouwriteit.Yourcompilerwillmostoftenoptimizeouttheindexeruseinreleasemode.Itiseasytomessaroundwithc-strings;thingssuchasdeletevsdelete[],exceptionsafety,evenhowtoreallocateac-string.
AndwhenyouhavetodealwithadvancedconceptslikehavingCOWstrings,andnon-COWforMTetc,youwillneedstd::string.
Ifyouareworriedaboutcopies,aslongasyouusereferences,andconstreferenceswhereveryoucan,youwillnothaveanyoverheadduetocopies,andit'sthesamethingasyouwouldbedoingwiththec-string.
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answeredAug17,2009at11:04
AbhayAbhay
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+1ThoughyoudidnotconsiderimplementationissueslikeDLLcompatibility,ugotCOW.
– Anonymous
Aug17,2009at12:35
whataboutIknowthatmychararrayin12bytes?IfIinstantiateastringforthatitmightnotbereallyefficientright?
– David天宇Wong
Aug16,2016at0:17
@David:Ifyouhaveextremelyperfsensitivecodethenyes.Youmightconsiderstd::stringctorcallasanoverheadinadditiontoinitializationofstd::stringmembers.ButrememberprematureoptimizationhasmadealotofcodebasesunnecessarilyC-styled,sobecareful.
– Abhay
Aug17,2016at14:17
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OneofthedifferenceisNulltermination(\0).
InCandC++,char*orchar[]willtakeapointertoasinglecharasaparameterandwilltrackalongthememoryuntila0memoryvalueisreached(oftencalledthenullterminator).
C++stringscancontainembedded\0characters,knowtheirlengthwithoutcounting.
#include
#include
#include
usingnamespacestd;
voidNullTerminatedString(stringstr){
intNUll_term=3;
str[NUll_term]='\0';//specificcharacteriskeptasNULLinstring
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