Definition
Inthedatastructure,storagedensity:theratioofthestoragecapacityofthenodedataitselftothestoragecapacityoftheentirenodestructure.
StorageDensity=(Theamountofstorageoccupiedbythenodedataitself)/(Thetotalamountofstorageoccupiedbythenodestructure)
Inthedatastructure,thedataelementisthedataThebasicunit,thedataelementisgenerallydefinedasanode.Therearedataandnon-datapartscontainedinthenode,suchasthepointerinthelinkedlist.Thestoragedensityisanindicatortomeasuretheutilizationofdataonthestoragespace,thatis,adataelementThepercentageofthespaceoccupiedbythedatainthestorageunittothestoragespaceofthisdataelement.
Arealdensity
Arealdensityisameasureoftheamountofinformationbitsthatcanbestoredinagivenlengthoftrack,surfacearea,oragivenvolumeofacomputerstoragemedium.Generally,higherdensityismoredesirablebecauseitallowsalargeramountofdatatobestoredinthesamephysicalspace.Therefore,densityisdirectlyrelatedtothestoragecapacityofagivenmedium.Densityalsousuallyhasadirectimpactonperformanceandpriceinaparticularmedium.
Disk
Atape-likedeviceisalsousedintheexternalmemoryofthecomputer.Themorecommonlyusedoneiscalledamagneticdisk,whichisaroundmagneticdiskinasquaresealedbox.Here,thepurposeofthisistopreventscratchesonthesurfaceofthedisk,resultingindataloss.
CD
CDisakindofobjectthatusesopticalinformationasstoragecarrierandusedtostoredata.Itisdividedintonon-rewritableopticaldiscs,suchasCD-ROM,DVD-ROM,etc.;andrewritableopticaldiscs,suchasCD-RW,DVD-RAM,etc.Theopticaldiscisadevicethatusestheprincipleoflasertoreadandwrite.Itisarapidlydevelopingauxiliarymemorythatcanstorevariousmultimediadigitalinformationsuchastext,sound,graphics,images,andanimation.Opticaldiscdefinition:thatis,compactdisc(CompactDisc)isanopticalstoragemediumdevelopedinmoderntimesthatisdifferentfromacompletelymagneticcarrier(forexample,magneto-opticaldiscisalsoanopticaldisc).TherecordingmediumisprocessedwithafocusedhydrogenionlaserbeamThemethodofstoringandreproducinginformation,alsoknownaslaserdisc.
Tape
Tapeisatape-shapedmaterialwithamagneticlayerusedtorecordsound,image,digitalorothersignals.Itisthelargestproductionandmostversatileone.Magneticrecordingmaterial.Itisusuallyformedbycoatingalayerofgranularmagneticmaterial(suchasneedle-shapedγ-Fe2O3magneticpowderormetalmagneticpowder)ontheplasticfilmtapebase(support)orevaporatingalayerofmagneticoxideoralloyfilm.Paperandcelluloidwereusedasthebaseforthefirsttime,mainlyusingpolyesterfilmwithhighstrength,goodstabilityandresistancetodeformation.
Example
Inthedatastructure,thedataelementisthebasicunitofdata.Generally,thedataelementisdefinedasanode.Thenodecontainsdatapartsandnon-dataPart,suchasthepointerinthelinkedlist,thefollowingusesanexampleofthelinkedlisttoexplainthestoragedensity:
typedefstructnode{
chardata[16];
structnode*next;
}LinkStrNode
Theabovedefinesadatanode,thisnodeincludestwoparts,thedatapart:data[16],whichisacharacterarray,Occupies16bytes,non-datapart:*next,isanodepointer,settooccupy4bytes,
Theabovestoragedensityis16/(16+4)=80%