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1、IOS学习笔记005―数组指针的概念及定义IOSlearningnotes一theconceptanddefinitionofarrayPointers1)arraypointer:PointerstoarrayelementsArraye1ementPointers:Avariableaddresses,anarraycontaininganumberofelements,eacharrayelementhasthecorrespondingaddress,pointervariablecanpointtoanarrayelement
2、(toaddressaparticularelementsinapointervariable)intheso-calledarrayelementpointeristheaddressofthearrayelements・Youcanpointtoanarrayelementwithapointervariable・Inta[10]二{1,3,5,7,9,11,13,15,17,19}:Int*p;P二&a[0];It'sequivalenttointtimespisequaltoa;Oranint・Equivalenttop=a;N
3、ote:arrayadoesnothaveanentirearrayoftables,representingtheaddressofthefirstelementofthearray."P二a;z，Thefunctionof"istheaddressofthefirstelementofanarraytothepointervariablep"insteadof''assigningthevalueofarrayatop〃1)arrayPointersareinitializedandusedA,usePointerstorefere
4、ncearrayelementsWhenthepointerpointstotheelement,theoperationisallowed:Addaninteger(with+or+=),suchasp+1Subtractaninteger(use-or-二)，suchaspTAddoperations,suchasp++,++pSotheself-subtracting,likep--,pTwoPointerswanttosubtract,suchaspp-p2(whichonlymakessensewhenplandp2point
5、toelementsinthesamearray)B,payattentionto;Iftheinitialvalueofpis&a[0],thenp+Ianda+Iaretheaddressofthearrayelementa[I],ortheypointtotheelementofanarraythenumberI.Theroleofanarraypointer:anelementthatindirectlyaccessesanarrayusingarrayPointers・Thedefinitionofanarraypointer
6、:int*p;Theinitializationofthearraypoinlet:inta[4]二{1,2,3,4};Int*p二a;//arraypointer,whichdefinesapointervariablethatpointstothefirstaddressofarraya(andthefirstaddressofthefirstelement,a[0]),andpointstothefirstelementofthearrayIsequivalentto:Inttimespisequaltoa,minusb,minu
7、sb.Thearraypointeraccessesthearray，selements:A)p+1meansthenextelementinthearrayB)p-1standsforthelastelementofthearrayConclusion:Toreferenceanarrayelement,youcanusethefollowingtwomethods:A)subscript:theformofa[I.B)pointermethod:*(a+I)or*(p+I)C)aisconstant(a++error),pisava
8、riable(p++),Summary:foraone-dimensionalarrayA)obtaintheaddressmethodofA[I]:A)&a[I];//taketheaddressdire
