Why does emoji have two different utf-8 codes? How to ...

But in a web tool bianma, all the two types of utf-8 code can be converted into emoji correctly. input code. ouput. So, my question is : Why ... Home Public Questions Tags Users Collectives ExploreCollectives FindaJob Jobs Companies Teams StackOverflowforTeams –Collaborateandshareknowledgewithaprivategroup. CreateafreeTeam WhatisTeams? Teams CreatefreeTeam CollectivesonStackOverflow Findcentralized,trustedcontentandcollaboratearoundthetechnologiesyouusemost. Learnmore Teams Q&Aforwork Connectandshareknowledgewithinasinglelocationthatisstructuredandeasytosearch. Learnmore Whydoesemojihavetwodifferentutf-8codes?Howtoconvertemojifromutf-8,useNSStringinios? AskQuestion Asked 5years,11monthsago Active 3yearsago Viewed 34ktimes 19 7 Wehavefoundanissue,thatsomeemojihavetwoutf-8codes,suchas: emojiunicodeutf-8anotherutf-8 😁U+1F601\xf0\x9f\x98\x81\xed\xa0\xbd\xed\xb8\x81 Butioslanguagecan'tdecodetheothertypeofutf-8,soresultinganerrorwhenidecodestringfromutf-8. Inalldocumentsifound,icanjustfindonetypeofutf-8codeforaemoji,nowheretofindtheother. Documentsireferencedincludes: emojicodelink wholeutf-8codelink Butinawebtoolbianma,allthetwotypesofutf-8codecanbeconvertedintoemojicorrectly. So,myquestionis: Whydoestherehavetwotypesofutf-8codesforoneemoji? Wherehasadocumentwhichincludesthetwotypesofutf-8codes? Howtocorrectlyconvertstringfromutf-8,usingNSStringinioslanguage? iosunicodeutf-8nsstringemoji Share Improvethisquestion Follow askedDec22'15at5:34 pinchwangpinchwang 35311goldbadge22silverbadges1212bronzebadges 4 ThishadmeintriguedasmyfirstthoughtwasthatthelongUTF-8representationwastwoUTF-8blocks.ItturnsoutthattherearetwovariationsofUTF-8,CESU-8andModifiedUTF-8,whichencodeUTF-16style.Youmaybeabletousethisarticleiphonedevsdk.com/forum/iphone-sdk-development/…towriteadecoderifthere'snosuitableiOS/Objective-Cnativedecoder. – AlastairMcCormack Dec22'15at11:33 @AlastairMcCormackThat'stheanswerIthink.Youshouldpostthatasananswer. – roeland Dec22'15at22:23 @user692793Pleaseneverposttextasimages,especiallynotcodeoroutput. – roeland Dec22'15at22:24 [email protected],butasI'mnotanObjective-CcoderI'llleaveittosomeoneelsetopickuptheglory:) – AlastairMcCormack Dec22'15at22:26 Addacomment  |  2Answers 2 Active Oldest Votes 16 0xF0,0x9F,0x98,0x81 IsthecorrectUTF-8encodingforU+1F601😁. 0xED,0xA0,0xBD,0xED,0xB8,0x81 IsnotavalidUTF-8sequence(*).Itshouldreallyberejected;iOSiscorrecttodoso. Thisisabuginthebianmatool:theconvertUtf8BytesToUnicodeCodePointsfunctionismorelenientaboutwhatinputitacceptsthanthespecifiedalgorithminegRFC3629. ThishappenstoreturnaworkingstringonlybecausethetooliswritteninJavaScript.HavingdecodedtheabovebytesequencetothebogussurrogatecodepointsequenceU+D83D,U+DE01itthenconvertsthatintoaJavaScriptstringusingadirectcode-point-to-code-unitmappinggiving\uD83D\xDE01.Asthisisthecorrectwaytoencode😁inaUTF-16stringitappearstohaveworked. (*:ItisavalidCESU-8sequence,butthatencodingisjust“bogusbrokenencodingforcompatibilitywithbadly-writtenhistoricaltools”andshouldgenerallybeavoided.) Youshouldnotusuallyencounterasequencelikethis;itistypicallynotworthcateringforunlessyouhaveaspecificsourceofthiskindofmalformeddatawhichyoudon'thavethepowertogetfixed. Share Improvethisanswer Follow editedOct7at7:59 CommunityBot 111silverbadge answeredDec22'15at23:03 bobincebobince 507k102102goldbadges631631silverbadges810810bronzebadges 3 Thankyouverymuchforanswer.WereadstringdatafromourserverwhichuseC++language,afterserverconvertunicodestringtoutf-8,thisissueoccurs.Onemorethingneedtomentionisthat,whenourclientreceivedataasastringvaluecstr,andprintf("%s",cstr)it'scorrect.ButwhenconvertstringtoNSString,NSString*ocstr=[[NSStringalloc]initWithBytes:cstr.c_str()length:cstr.length()encoding:NSUTF8StringEncoding];ocstrresultsasnil.whyappledonotsupporttheCESU-8sequence?Dowehavefunctiontoresolvetheissue? – pinchwang Dec23'15at2:12 IwouldfirstlookattheC++serverUTF-8encoder,toseeifitcanbefixedproperlyatsource.CESU-8isconsideredanundesirableanomalythatyou'dneverdeliberatelywanttouse;mostsystemsdon'tsupportit.Ifyouhavetoacceptityou'llneedtowriteyourownCESU-8decoderwalkingthroughtheinputbytearray(oruseanexistinglibrary,egICUthoughthatwouldbeareallyheavydependencyjustforthis). – bobince Dec23'15at11:36 Justasasidenote,thereisoneparticularlybothersomesourceofencodinglikethis:JNI(JavaNativeInterface).Ifyouattempttoretrieve"UTF-8"bytesfromaJavastringyouwillreceivethe"modifiedUTF-8"variant.Thatisaratherlargesourceofmalformeddatathatcannotbefixed,unfortunately. – borrrden Jul12'18at17:02 Addacomment  |  -3 Thisworkedformeinphptosendamessagewithemojitotelegrambot: $message_text="\xf0\x9f\x98\x81"; Share Improvethisanswer Follow answeredJun12'18at9:41 PolinaPolina 1133bronzebadges 1 Thisisjusttoo-off-topic. – Moradnejad Apr30'19at11:47 Addacomment  |  YourAnswer ThanksforcontributingananswertoStackOverflow!Pleasebesuretoanswerthequestion.Providedetailsandshareyourresearch!Butavoid…Askingforhelp,clarification,orrespondingtootheranswers.Makingstatementsbasedonopinion;backthemupwithreferencesorpersonalexperience.Tolearnmore,seeourtipsonwritinggreatanswers. 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