Introduction
InternalcodereferstothebinarycharactercodeusedinthecomputerChinesecharactersystem.Itistheexchangecodebetweenthecommunicationinput,outputandthesystemplatform.TheinternalcodecanachieveuniversalandhighThepurposeofefficienttransmissionoftext.Forexample,whatisstoredandcalledinMSWordisinternalcodeinsteadofgraphictext.EnglishASCIIcharactersarerepresentedbyaone-byteinternalcode.Chinesecharacterssuchasthenationalstandardcharacterset,GB2312,GB12345,andGB13000allusedouble-byteinternalcodes,GB18030(27,533Chinesecharacters)double-byteinternalcodeChinesecharactersare20,902,andtheremaining6,631Chinesecharactersuseafour-byteinternalcode.
Classification
Characterencoding:Thecharacterencodingisthebinarynumbercorrespondingtothecharactersofthecharacterset.ThemostcommonlyusedcharactersetisANSI,andthebinaryencodingcorrespondingtotheANSIcharactersetisCalledANSIcode,DOSandWindowssystemsbothuseANSIcode,butthecharactercodeusedinthesystemmustundergobinaryconversion,whichiscalledsysteminternalcode.
Chinesecharacterinternalcode:ANSIcodeisasinglebyte(8-bitbinarynumber)encodingset,whichcanonlyrepresent256charactersatmost,andcannotrepresentmanyChinesecharacters.TheANSIcodeofvariouscountriesandregionsOnthebasisofthis,avarietyofdifferentChinesecharacterencodingsetsaredesignedtobeabletohandlealargenumberofChinesecharacters.ThesecodesusesinglebytetorepresentANSIEnglishcharacters(thatis,compatiblewithANSIcode),andusedoublebytestorepresentChinesecharacters.SincetherecanonlybeoneChinesecharacterinternalcodeinasystem,thecharactersofotherChinesecharacterinternalcodescannotberecognized,whichcausescommunicationinconvenience.
GBcode:GBcodeisasimplifiedChinesecharactercodingschemeannouncedbythecountryin1980,andiswidelyusedinmainlandChinaandSingapore,alsoknownasthenationalstandardcode.Thenationalstandardcodeencodes6763Chinesecharactersets,coveringmostoftheChinesecharactersinuse.
GBKcode:GBKcodeisanextendedcharacterencodingofGBcode,whichencodesmorethan20,000simplifiedandtraditionalChinesecharacters.SimplifiedversionsofWin95andWin98bothuseGBKassysteminternalcode.
BIG5code:BIG5codeisaChinesecharacterencodingfortraditionalChinesecharacters,whichiscommonlyusedincomputersystemsinTaiwanandHongKong.
HZcode:HZcodeisaChinesecharactercodewidelyusedontheInternet.
ISO-2022CJKcode:ISO-2022isacodingstandardestablishedbytheInternationalStandardsOrganization(ISO)forvariouslanguagecharacters.Two-byteencodingisadopted,inwhichtheChineseencodingiscalledISO-2022CN,andtheJapaneseandKoreanencodingsarecalledJPandKRrespectively.Generally,thethreearecollectivelyreferredtoastheCJKcode.TheCJKcodeismainlyusedintheInternetnetwork.
Unicodecode:Unicodecodeisalsoaninternationalstandardcode,whichusestwo-byteencodingandisnotcompatiblewithANSIcode.Itisusedinthenetwork,Windowssystemandmanylarge-scalesoftware.
Internalcodeconversion
Duetohistoricalandregionalreasons,sometimesmultipleencodingschemesappearinonetext,especiallyChinesecharacters.Sincecharactersdifferentfromthesysteminternalcodecannotbedisplayednormallyinthesystem,theinternalcodeconversionofthecharactersmustbecarriedout,thatis,thecharactersthatarenotthesysteminternalcodeareconvertedintotheinternalcodecharactersthatcanberecognizedbythesystem.NJStarissuchanexcellentsoftware.OtherssuchasSitongLifang,MagicWin98,Cross-StraitCommunication,ChineseCharacterCommunication,etc.areallsuchinternalcodeconversiontools.
Mutualconversion
Theconversionrelationshipbetweenlocationcode,nationalstandardcodeandmachineinternalcode:
(1)Thelocationcodeisfirstconvertedintohexadecimalnumberrepresentation
(2)(Hexadecimalrepresentationoflocationcode)+2020H=nationalstandardcode;
(3)nationalstandardcode+8080H=machineinternalcode
Example:TakingtheChinesecharacter"大"asanexample,theareacodeof"大"is2083
Solution:1.Theareacodeis20,andthebitnumberis83
2.Thelocationnumber2083isconvertedtohexadecimalandexpressedas1453H
3,1453H+2020H=3473H,getthenationalstandardcode3473H
4,3473H+8080H=B4F3H,gettheinternalcodeB4F3H
Summary:Tworepresentationsofcharacterencoding:ASCII(characterrepresentation);GB2312(nationalstandardcode,Chinesecharacterencoding)
Relateddifferences
1.Theexternalcodeisthecharacteryouinputfromtheoutsideworld.Afterthischaracterisinput,therewillbeacorrespondinglocationcode(thatis,a94*94checkerboardgrid,theChinesecharacteryouinputwillcorrespondtoagridinside,row+columnisusThearea+locationhere),
2,thelocationcodecanbeconvertedintothenationalstandardcodeafterconversion(sothelocationcode→nationalstandardcodestepjustmeansconversion),
3,Thenationalstandardcodecanbeconvertedintotheinternalcode(usuallyrepresentedbyahexadecimalnumber)afterconversion.