C++面向对象程序设计双语教程（第3版）课件全套 class 1-Introduction-class 14-template

ObjectivesTounderstandwhatacomputerprogrammingisToknowhowtowriteaprogramTorecognizetwoprogrammingmethodologies01HowtoWriteaProgram?02Two

ProgrammingMethodologies01HowtoWriteaProgram?WhatisProgramming?Problem(orTask):Abouta

student’sgradesRequirements:Astudentlearnstwocoursesatthisterm,thatis,OOP,math.Youneedtoinputtwogradesdisplaytwogradesdisplaymessagescondition:agrade<60,displaymessages“youfailedxxx”;otherwise,displaymessage“youpassedxxx”Calculatethesumoftwogradesandaverage,anddisplayresultsCaseStudy1ComputerProgramming–planningorschedulingtheperformanceofataskoraproblem,thatis,itisaprocessthatleadsfromoriginalcomputingproblemtoexecutablecomputerprogram.HowtoWriteaProgram?Phase1:Problem-solving-planningtheprocessoftask(1)Inputtwogrades;(2)Displaythesetwogrades;(3)Ifoneoftwogradesislessthan60,display“youfailedxxx”,otherwisedisplay“youpassedxxx”(4)Calculatethesumoftwogradesandaverage;(5)Displaytheresults.PseudocodeStep1.AnalysisandspecificationHowtoWriteaProgram?Step2.Generateanalgorithmbyusingaflowchart

gradeOfOPP<60yesnoinputgradeOfOPP,gradeOfMathoutputsum,averageStartEndgradeOfMath<60sum=gradeOfOPP+gradeOfMathoutputgradeOfOPP,gradeOfMathoutput“youpassedOPP”yesnooutput“youfailedOOP”output“youfailedMath”output“youpassedMath”average=sum/2Algorithm:astep-by-stepprocedureforsolvingaproblem.Step3.VerifyHowtoWriteaProgram?Step1.Youmightconsidersomequestionsinthecontextofprogramming.1.WhatdoIhavetoworkwith–thatis,whatismydata?gradeOfOOP,gradeOfMath,sum,average2.Whatdothedataitemslooklike?–data

types,int,double3.HowwillIknowwhenIhaveprocessedallthedata?–algorithm4.Howmanytimesistheprocessgoingtoberepeated?-structure5.Whatshouldmyoutput

looklike?6.Whatspecialerrors

mightcomeup?Phase2:Implementation–writeaprogramHowtoWriteaProgram?Step2.TranslatethealgorithmtoaprogramwithCStep3.Testtheprogram#include

<stdio.h>intmain(){intgradeOfOOP,gradeOfMath,sum;floataverage;scanf("%d%d",&gradeOfOOP,&gradeOfMath);printf("OOP:%dMath:%d\n",gradeOfOOP,gradeOfMath);if(gradeOfOOP<60) printf("youfailedOOP\n");else printf("youpassedOOP\n");if(gradeOfMath<60) printf("youfailedMath\n");else printf("youpassedMath\n");sum=gradeOfOOP+gradeOfMath;average=(float)sum/2;printf("sum%daverage%6.2f\n",sum,average);return0;}(1)Input:50,69(2)Input:85,55(3)Input:80,69HowtoWriteaProgram?Phase3:Maintenance(维护)–Modifytheprogramtomeetchangingrequirementsorcorrecterrors.#include

<stdio.h>intmain(){intgradeOfOOP,gradeOfMath,sum;floataverage;scanf("%d%d",&gradeOfOOP,&gradeOfMath);printf("OOP:%dMath:%d\n",gradeOfOOP,gradeOfMath);if(gradeOfOOP<60) printf("youfailedOOP\n");else printf("youpassedOOP\n");if(gradeOfMath<60) printf("youfailedMath\n");else printf("youpassedMath\n");sum=gradeOfOOP+gradeOfMath;average=(float)sum/2;printf("sum%daverage%6.2f\n",sum,average);return0;}Whaterrorsmightcomeup？

Formanystudents?Practice-orientedHowtoWriteaProgram?Phase1:Problem-solving:(1)analysisandspecification(2)generatesolution(algorithm)(3)verificationPhase2:Implementation:(1)concretesolution(writingprogram)(2)testPhase3:Maintenance:

(1)reuse

(2)maintainWritingaprogramhasthethree-phaseprocess02ProgrammingMethodologiesProgrammingMethodologies1.thestructuredprogramming(modular,procedural)e.g.C/C++,Pascal2.theobject-orientedprogramming(OOP)e.g.C++,Java,C#Abstractioniscrucialtobuildingthecomplexsoftwaresystems.Dataabstractioncanbesummedupasconcentratingontheaspectsrelevanttotheproblemandignoringthosethatarenotimportantatthemoment.DataAbstractionTwopopularmethodologiestoprogrammingStructuredProgrammingProblem:solveaquadraticequationDatavariables:a,b,c,root1,root2Datatype:float/doubleInputdata:a,b,cOutputdata:root1,root2Algorithm:

Problem-solvingCaseStudy2StructuredProgrammingImplementation#include

<stdio.h>#include

<math.h>intmain(){floata,b,c;floatroot1,root2;printf("Enterthevaluesofa,bandc:\n");scanf("%f%f%f",&a,&b,&c);if(fabs(a)<=1e-6||fabs(b)<=1e-6) printf("theequationhasnorealroots!\n");else{floatdisc=b*b-4*a*c;if(disc<0)printf("theequationhasnorealroots\n");if(disc==0){root1=root2=-b/(2*a);printf("therootis%6.2f",root1);}if(disc>0){root1=(-b+sqrt(disc))/(2*a);root2=(-b-sqrt(disc))/(2*a);printf("therootis%6.2fand%6.2f",root1,root2); }}return0;}StructuredProgramming#include

<stdio.h>#include

<math.h>>boolquadratic(float

a,float

b,float

c,float*root1,float*root2){if(fabs(a)<=1e-6||fabs(b)<=1e-6)return

false;else{floatdisc=b*b-4*a*c;if(disc<0)return

false;if(disc==0){*root1=*root2=-b/(2*a);return

true;}if(disc>0){*root1=(-b+sqrt(disc))/(2*a);*root2=(-b-sqrt(disc))/(2*a);return

true;}}}intmain(){float_a,_b,_c;float_root1,_root2;printf("Enterthevaluesofa,bandc:\n");scanf("%f%f%f",&_a,&_b,&_c);if(quadratic(_a,_b,_c,&_root1,&_root2))printf("therootsare%6.2fand%6.2f",_root1,_root2);elseprintf("theequationhasnorealroot.\n");return0;}Dividingaproblemintosmallersub-problemsiscalledstructureddesign.Thisprocessofimplementingastructureddesigniscalledstructuredprogramming.StructuredProgrammingStructuredProgrammingDividingaproblemintosmallersub-problems.Eachsub-problemisthenanalysed,andasolutionisobtainedtosolvethesub-problem.Thesolutionstoallsub-problemsarecombinedtosolvetheoverallproblem.Characteristics:Top-downdesign,stepwiserefinementandmodularprogrammingBenefit:improvingtheclarity,quality,anddevelopmenttimeofa

computerprogram.StructuredProgrammingquadratic(…){a,b,c,root1,root2}intmain(){……}(function)(function1)(function2)float_a,_b,_c,_root1,root2StructuredProgrammingProblem:Student’sgrades(1)Inputtwogrades;(2)Displaythesetwogrades;(3)Ifoneoftwogradesislessthan60,display“youfailedxxx”,otherwisedisplay“youpassedxxx”(4)Calculatethesumoftwogradesandaverage;(5)Displaytheresults.MainfunctionInputgradeoutputgradeDisplaypassMCalculationsum_averageoutputsum_averageCaseStudy1Object-OrientedProgramming(OOP)#include

<stdio.h>#include

<math.h>class

quadratic_equation{public:quadratic_equation(float

aa,float

bb,float

cc):a(aa),b(bb),c(cc){}boolquadratic(float*root1,float*root2){if(fabs(a)<=1e-6||fabs(b)<=1e-6)return

false;else{floatdisc=b*b-4*a*c;if(disc<0)return

false;if(disc==0){*root1=*root2=-b/(2*a);return

true;}if(disc>0){*root1=(-b+sqrt(disc))/(2*a);*root2=(-b-sqrt(disc))/(2*a);return

true;}}}private:floata,b,c;};class,auser-defineddatatypeintmain(){float_a,_b,_c;float_root1,_root2;printf("Enterthevaluesofa,bandc:\n");scanf("%f%f%f",&_a,&_b,&_c);quadratic_equationqe(_a,_b,_c);if(qe.quadratic(&_root1,&_root2))printf("therootsare%6.2fand%6.2f",_root1,_root2);elseprintf("theequationhasnorealroot.\n");return0;}Themethodofobjectqeintmain(){float_a,_b,_c;float_root1,_root2;printf("Enterthevaluesofa,bandc:\n");scanf("%f%f%f",&_a,&_b,&_c);if(quadratic(_a,_b,_c,&_root1,&_root2))printf("therootsare%6.2fand%6.2f",_root1,_root2);elseprintf("theequationhasnorealroot.\n");return0;}Usingobjectsandtheirinteractions(methods)todesignprogramsiscalledOOdesign.ThisprocessofimplementinganOOdesigniscalled

OOprogramming.ObjectsObject-OrientedProgramming(OOP)qe1qe2qe4qe3MainfunctionObject-OrientedProgramming(OOP)Object-orientedprogramming(OOP)isawidelyusedinthemain-streamprogrammingnowadays.Object-orientedprogrammingisaprogrammingparadigmthatuses“objects”whichcontaindataandoperations(methods).Thefirststepistoidentifythecomponentscalledobjects,whichformthebasisofthesolution,andtodeterminehowtheseobjectsinteractwithoneanother.Thenextstepistospecifyforeachobjecttherelevantdataandpossibleoperationstobeperformedonthedata.ProgrammingmethodCharacteristicsofOOPClass–user-definedtypeMethod–operations,functionsMessagepassingAbstraction–programmingprocessEncapsulation–singleunitInheritance–relationshipbetweenclassesPolymorphism-interfaceSummaryProgrammingisaprocessthatleadsfromoriginalcomputingproblemtoexecutablecomputerprogram.Howtowriteaprogram,havingthethree-phaseprocess,i.e.,problem-solving,implementationandmaintenance.TwopopularmethodologiestoprogrammingObjectivesTobeabletoconstructasimpleC++programTo

beabletobefamiliarwithinput/outputstreamToknowhowtouseC++constantsTounderstandhowtoconstructprogramsmodularlybyusingfunctions(data

abstraction)01C++ProgramStructure03Constants02Input/OutputStream04Functions01C++ProgramStructureABriefDescriptionofC++C++isageneral-purposeprogramminglanguagewithadvantagestowardsthesystemprogrammingthatisabetterCsupportsdataabstractionsupportsstructuredprogrammingsupportsobject-orientedprogrammingsupportsgenericprogrammingC++ProgramStructureProblem:Writeaprogramforagradebookofagivencourse.Thegradebookincludescourse’sname,hourandlecturer,aswellasstudent’sID,nameandgradeInputallinformationoncourseandstudent;Calculatetheaveragegradeofthecourse;Printthegradebook.CaseStudy1Requirements:C++ProgramStructureDataToacourse,name,hourandlecturer,averagegrade;Tomanystudents,ID,nameandgrade;2.Datatypesname,lecturer-string(char*),grade-int,average-float3.Outputagradebookhavingacoursename,hourandlecturer,manystudents’ID,nameandgrade,

and

course

average

grade.4.Procedures(algorithm)InputalldataincludeacourseandstudentsCalculateaveragegradePrintagradebookProblem-solvingIDNameGrade200405XXXwang89………average70.67Name:OOPHour:48Lecturer:LIUJMGradeBookofOOPC++ProgramStructuremainsetCoursesetStudentaverageGradeprintCourseprintStudentGradeprintGradeBookinputStructuredprogrammingC++ProgramStructure////////////////////////////////////////////////////////////////////////gradebook.cpp//Theprogramreadscourseinformationandstudents'gradefromthe//console,calculatestheaveragegradeandoutputsstudents'grades.//////////////////////////////////////////////////////////////////////#include

<iostream>#include

<string>#include

<iomanip>using

namespacestd;//declarationofconstantsconst

intstudentNum=5;//declarationofinputfunctionsvoidsetCourseInfo(string&cName,string&lectName,int&cHour);voidsetGrade(int(&sNo)[studentNum],string(&sName)[studentNum],

int(&g)[studentNum]);doubleaverage(int

g[]);//declarationofoutputfunctionsvoidprintCourseInfor(string,string,int);voidprintGradeBook(int*,string*,int*);intmain(){stringcourseName;stringlecturer;intcourseHour;intstudentNo[studentNum];stringstudentName[studentNum];intgrade[studentNum];//ReadthecourseandstudentdatasetCourseInfo(courseName,lecturer,courseHour);setGrade(studentNo,studentName,grade);//DisplaythecourseandstudentdataprintCourseInfor(courseName,lecturer,courseHour);printGradeBook(studentNo,studentName,grade);return0;}C++ProgramStructuredoubleaverage(int

g[]){intsum=0;for(inti=0;i<studentNum;i++) sum+=g[i];return

static_cast<double>(sum)/studentNum;}C++ProgramStructure//ReadthecourseandstudentdatavoidsetCourseInfo(string&cName,string&lectName,int&cHour){cout<<"EntercourseInformation\n";cin>>cName>>lectName>>cHour;}voidsetGrade(int(&sNo)[studentNum],string(&sName)[studentNum],

int(&g)[studentNum]){cout<<"Enterstudent'sgrades\n";for(inti=0;i<studentNum;i++){sNo[i]=i;cin>>sName[i]>>g[i];}}C++ProgramStructurevoidprintCourseInfor(string

cName,string

lectName,int

cHour){cout<<"Coursename:"<<cName

<<"Coursehour:"<<cHour

<<"Lecturer:"<<lectName<<endl;}voidprintGradeBook(int*sNo,string*sName,int*sg){cout<<"----------------------------\n";cout<<"StudentNoNameGrade\n";for(inti=0;i<studentNum;i++)cout<<setw(9)<<right<<sNo[i]<<setw(10)<<sName[i]<<setw(7)<<right<<sg[i]<<endl;cout<<"----------------------------\n";cout<<"Theaveragegrade:"<<average(sg)<<endl;}C++ProgramStructureAcommonstructureofsimple,onefile,C++programsCommentsdescribe

theprogram,name,…Includestatementsspecifytheheaderfilesforlibraries.//gradebook.cpp//Theprogramreadscourseinformation…Usingnamespacestatement.#include<iostream>usingnamespacestd;LinecommentsBlockcommentsGlobaldeclarations(consts,types,variables,...).const

intstudenNum=5;Functionprototypes(declarations)voidprintGradeBook(int*,string*,int*);The

mainfunctiondefinitionintmain(){stringcourseName;stringlecturer;intcourseHour;intstudentNo[studentNum];stringstudentName[studentNum];intgrade[studentNum];//ReadthecourseandstudentdatasetCourseInfo(courseName,lecturer,courseHour);setGrade(studentNo,studentName,grade);……}C++ProgramStructureFunctiondefinitionsdoubleaverage(int

g[]){intsum=0;for(inti=0;i<studentNum;i++) sum+=g[i];return

static_cast<double>(sum)/studentNum;}02Input/Output

Stream//ReadthestudentdatavoidsetGrade(int(&sNo)[studentNum],string(&sName)[studentNum],

int(&g)[studentNum]){cout<<"Enterstudent'sgrades\n";for(inti=0;i<studentNum;i++){sNo[i]=i;cin>>sName[i]>>g[i];}}Input/OutputStreamOutputstreamInputstreamTheiostreamlibrarydefinesinput/outputforeverybuilt-intype.#include<iostream>Input/OutputStreamAstream

isasequenceofcharactersfromthesourcetothedestination.Therearetwotypesofstreams:Inputstream:Asequenceofcharactersfromaninputdevice(keyboard)tothecomputer(variables).Outputstream:Asequenceofcharactersfromthecomputer(variables)toanoutputdevice(screen).Input/OutputStreamTheextractionoperator(>>)isusedasaninputoperator.Inputstreamisfromthedevicetovariables.Keyword

cinisthestandardinputstream.Theinsertionoperator(<<)isusedasoutputoperator.Outputstreamisfromvariablestothedevice.Keyword

coutisthestandardoutputstream.cin>>courseName>>courseHour>>lecturer;

cout<<“Coursename:“<<courseName<<endl;ConsoleinputConsoleoutput//ReadthestudentdatavoidsetGrade(int(&sNo)[studentNum],string(&sName)[studentNum],int(&g)[studentNum]){cout<<"Enterstudent'sgrades\n";for(inti=0;i<studentNum;i++){sNo[i]=i;cin>>sName[i]>>g[i];}}Input/OutputstreamOutputstream(printf)Inputstream(scanf)03ConstantsConstantsTheconst

keywordmeansthatavaluedoesnotchangedirectly.Aconstantmustbeinitialized.#include

<iostream>#include

<string>#include

<iomanip>using

namespacestd;//declarationofconstantsconst

intstudentNum=5;A#defineisamacrowhichreplacesthemacro-namewithauser-definedtextstatement.Aconstidentifierallowsavariabletobeconstantthroughoutthefile.Constantsconstintmodel=90;constintv[]={1,2,3,4};constintx;intmain(){model=200;v[2]++;}Example//error–cannotbechanged//error–cannotbechanged//error-don’tinitializevoidf(){charstr[]="hello";char*str1=str;const

char*p1=str;//valueisconstant//p1[2]='w';//errorp1=str1;char*constp2=str;//addressisconstantp2[2]='w';//p2=str1;//errorconst

char*constp3=str;//p3[2]='w';//error//p3=str1;//error}04FunctionsFunctionsintmain(){stringcourseName;stringlecturer;intcourseHour;intstudentNo[studentNum];stringstudentName[studentNum];intgrade[studentNum];//ReadthecourseandstudentdatasetCourseInfo(courseName,lecturer,courseHour);setGrade(studentNo,studentName,grade);//DisplaythecourseandstudentdataprintCourseInfor(courseName,lecturer,courseHour);printGradeBook(studentNo,studentName,grade);return0;}Functions:programisbrief.easilymaintainenhancetheefficiencyofprogrammingreusableWhytousefunctions?Thefunctionalfeaturesofaprogramcanbesubdividedintoblocksofcodeknownas

functions.intmain(){…….setCourseInfo(courseName,lecturer,courseHour);}voidsetCourseInfo(string&cName,string&lectName,int&cHour){cout<<"EntercourseInformation\n";cin>>cName>>lectName>>cHour;}voidsetCourseInfo(string&cName,string&lectName,int&cHour);DeclarationandDefinitionofFunctionsAdeclarationestablishesthenameofthefunction,thetypeofreturnedbythefunction,theparameternumbersandtypesoftheparameterlist.declaration-prototypeFunctionbodyFunctiondefinitionFunctioncallHowtousefunctions?FunctionsignatureFunctionheaderFunctionswithDefaultArguments/ParametersProblem:Inquireastudent’sgradeinwhichispassorfail.intmain(){setCourseInfo(courseName,lecturer,courseHour);setGrade(studentNo,studentName,grade);inttempNo;cout<<"Inquireastudent'sgrade.EnterastudentID\n";cin>>tempNo;cout<<gradeResult(grade[tempNo])<<endl;return0;}chargradeResult(int,int=60);DefaultparameterchargradeResult(int

gradeOne,int

passValue){if(gradeOne>=passValue) return

'P';else return

'F';}DefaultargumentCaseStudy1-1FunctionswithDefaultParametersA

defaultparameterisafunctionparameter

thathasadefaultvalueprovidedtoit.chargradeResult(int,int=60);Adefaultparameteristypecheckedatthe

timeofthefunctiondeclarationandevaluatedatthetimeofthecall.(1)Iftheuserdoesnotsupplyavalueforthisparameter,thedefaultvaluewillbeused;(2)Iftheuserdoessupplyavalueforthedefaultparameter,theuser-suppliedvalueisusedinsteadofthedefaultvalue.FunctionswithDefaultParametersvoidprint(intval1=10,intval2=20,intval3=30);intmain(){print();print(31);print(31,10);print(31,16,15);}voidprint(intval1,intval2,intval3){cout<<val1<<val2<<val3<<endl;}Result:102030312030311030311615definitionFunctioncallWhentherecanexistmorethanoneparameterintheparameterlist,forexample,declarationLeftmostcriteria:fromlefttorightFunctionswithDefaultParametersvoidprint(intval1=10,intval2=20,intval3);voidprint(intval1=10,intval2,intval3=30);

voidprint(intval1,intval2=0,intval3=0);//error//error//okAlldefaultparameterswithindeclarationordefinitionmustbetherightmostparameters.Rightmostcriteria:fromrighttoleftFunction

OverloadingProblem:OutputthegradebookwithstudentIDandgrade.Twoormorefunctionshavethesamenameinthesamescopeiscalledfunctionoverloading.voidprintGradeBook(int*sNo,string*sName,int*sg);voidprintGradeBook(intsNo[],intg[]);C++allowsyoutospecifytwoormoredefinitionsfora

function

name

inthesamescope.Thecompilerwillneedtodeterminewhichfunctiontoexecutebasedonthefunctionsignature.Howtodo?CaseStudy1-2Function

OverloadingvoidprintGradeBook(int

sNo[],int

g[]){cout<<"----------------------------\n";cout<<"StudentNoGrade\n";for(inti=0;i<studentNum;i++) cout<<sNo[i]<<g[i]<<endl;cout<<"----------------------------\n";cout<<"Theaveragegrade:"<<average(g)<<endl;}voidprintGradeBook(int*sNo,string*sName,int*sg){cout<<"----------------------------\n";cout<<"StudentNoNameGrade\n";for(inti=0;i<studentNum;i++) cout<<sNo[i]<<sName[i]<<sg[i]<<endl;cout<<"----------------------------\n";cout<<"Theaveragegrade:"<<average(sg)<<endl;}printGradeBook(studentNo,grade);printGradeBook(studentNo,studentName,grade);voidprintGradeBook(int*sNo,string*sName,int*sg);voidprintGradeBook(intsNo[],intg[]);Whenyoudefineoverloadedfunctions,youmustprovideaparameterlistwithdifferentparameters.Function

Overloading-HowtoCallanOverloadedFunctionMakingacalltoanoverloadingfunctionresultsinoneofthethreepossibleoutcomes:AmatchisfoundNomatchisfoundAnambiguousmatchisfoundFunction

Overloading–HowtoCallanOverloadedFunctionTrytofindanexactmatchTrytofindamatchthroughpromotions

booltoint

chartoint

e.g.charc=‘a’;

shorttoint

floattodoubleTrytofindamatchthroughstandardconversions

inttodouble

doubletointe.g.doublea=3.4;intn=(int)a;

doubletolongdoubleT*tovoid*

derived*toBase*

inttounsignedintCallingcriteriaWhenanoverloadedfunctioniscalled,asetofcriteriaaretriedtofindinorder:Function

Overloading-HowtoCallanOverloadedFunctionvoidprint(int);voidprint(char*)voidprint(double);voidprint(long);voidprint(char);voidh(charc,inti,shorts,floatf){print(c);print(i);print(s);print(f);print(‘a’);print(49);print(“a”);}//exactmatch//exactmatch//promotionmatch//promotionmatch//exactmatch//exactmatch//exactmatchFunction

Overloading–AmbiguousMatchDeclaringafewoverloadedfunctionscanleadtoambiguities.#include

<iostream>using

namespacestd;voidprint(double

d){cout<<

d

<<endl;}voidprint(long

l){cout<<

l

<<endl;}intmain(){print(1.0);//okprint(1L);//okprint(1);//errorreturn0;}datatypeambiguousmatchFunction

Overloading-AmbiguousMatch#include

<iostream>using

namespacestd;voidprint(double

d,double

f=1.0){cout<<

d

<<

f

<<endl;}voidprint(double

d){cout<<

d

<<endl;}intmain(){print(1,2);//okprint(10);//error-ambiguousargumentsreturn0;}Callafunctioncarefullywhendefaultparametersandfunctionoverloadingareinthesameprogram.SummaryC++programstructureInput/OutputstreamConstantsFunctionsDeclarationDefinitionDefaultparametersOverloadedfunctionObjectivesTounderstandthemechanismusedtopassinformationbetweenfunctionsTo

beabletousereferencestopassargumentstofunctionsToknowhowthenamespaceworksout01ReviewPointers03Namespaces02References01ReviewPointersintmain(){intx;//Anormalintegerint*p=nullptr;//Declareapointertoanintegerp=&x;//Readit,"assigntheaddressofxtop"cout<<&x<<"|"<<&p<<endl;cin>>x;//Putavalueinxcout<<p<<"\t"<<*p<<"\n";cout<<x<<"\n";return0;}Pointers0012FF7C:x0012FF78:p0012FF7C7Notetheuseofthe*togetthevalueAvariablewhichstorestheaddressofanothervariableiscalleda

pointer.Pointershaveabasicdatatype,isreferredtoasacompoundtype.Pointersaresaidto“pointto”thevariablewhoseaddresstheystore.Result:0012FF7C|0012FF7870012FF7C77PointersPointersareaptlynamed:they“point”tolocationsinmemory.Pointersareanextremelypowerfulprogrammingtool.Pointerscanmakesomethingsmucheasier,helpimproveyourprogram‘sefficiency,andevenallowyoutohandleunlimitedamountsofdata.Pointersareoftendifficulttounderstand,andevenexperiencedprogrammersoftenfeelawfulbyerrorscausedbydebuggingpointers.PointersPointerscanrefereithertoamemoryaddressitself,ortoavariablethatstoresamemoryaddress.

Apointerisdeclaredinthefollowingcases:Ifyouwantavariablethatstoresamemoryaddressint*p;Ifavariablestorestheaddressofanothervariable,yousaythatitis“pointingto”thatvariable.

int*p=&x;Ifyoupassapointervariableintoafunction,you'repassingthevaluestoredinthepointer--thememoryaddress.voidf(int*p);Ifyouwanttomanipulateamemoryaddress,yourefertoitasamemoryaddress.intarr[]={2,3,4,5};int*p=arr;*++p;02ReferencesReferencesC++referencesallowyoutocreateasecondnameforavariablethatyoucanusetoreadormodifytheoriginaldatastoredinthatvariable.

A

reference

referstoanotherbasic

datatype,isreferredastoacompoundtype.A

reference

isanaliasoranalternativenameofavariable(anobject).intmain(){inti=10;int&r=i;}referenceSyntaxtodeclareareferencevariable:basictype&variableNameAreferencevariablemustbeinitializedMemoryResult:i1=5r=5&i1=0012FF7C&r=0012FF7C--------------------i1=8i2=8r=8&i1=0012FF7C&i2=0012FF70&r=0012FF7CReferencesintmain(){