C++面向对象程序设计双语教程（第3版）课件 class 8-operator overloading-1-class 14-template - 副本

ObjectivesToknowwhyneedsoperatoroverloadingToknowwhatoperatorfunctionsareTo

be

abletodefinebinaryoperatorfunctionTobeabletodefineunaryoperatorfunction01Introduction03BinaryOperatorOverloading02OperatorFunctions04UnaryOperatorOverloading05CaseStudy01IntroductiontoOperatorOverloadingIntroductiontoOperatorOverloadingForexample,built-inoperators,+,-,=,<=,[],>>,<<2+3,3.4+5.4,‘a’+’b’Usingthesamenameforoperationsondifferenttypesisknownasoverloading.Operatoroverloading:Redefinemostofthebuilt-inoperatorsavailableforoperationson

user-definedtypes(abstractdatatypes).class

MyInteger{public:MyInteger(int=0);intget()const;MyIntegeraddition(const

MyInteger&);MyIntegermultiplication(const

MyInteger&);private:intvalue;};WhyNeedsOperatorOverloading?MyIntegervalue:int+MyInteger(int=0)+~MyInteger()+addition(constMyInteger&):MyInteger+multiplication(constMyInteger&):MyInteger+get():intconstCaseStudy1DefineaMyIntegerclasswithavalueattribute.Youneeddothefollowingtask:addtwoMyIntegerobjectsmultiplytwoMyIntegerobjectsWhyNeedsOperatorOverloading?intmain(){MyIntegeri1(10),i2(25);cout<<i1.get()<<

","

<<i2.get()<<endl;MyIntegeri3;i3=i1.addition(i2);cout<<i3.get()<<endl;i3=i1.multiplication(i2);cout<<i3.get()<<endl;return0;}i3=i1+i2;i3=i1*i2;MyInteger

MyInteger::addition(const

MyInteger&myint){return

MyInteger(this->value+myint.value);}MyInteger

MyInteger::multiplication(const

MyInteger&myint){return

MyInteger(this->value*myint.value);}MyInteger::MyInteger(int

v):value(v){}int

MyInteger::get()const{returnvalue;}MyInteger::~MyInteger(){}MyIntegervalue:int+MyInteger(int=0)+~MyInteger()+addition(constMyInteger&):MyInteger+multiplication(constMyInteger&):MyInteger+get():intconstWhyNeedsOperatorOverloading?Definingoperatorsforuser-definedtypeallowsaprogrammertoprovideamoreconventionalandconvenient

notationformanipulatingobjects.MyIntegeri3;i3=i1+i2;i3=i1*i2;intn;cin>>n;cout<<n;class

MyInteger{public:MyInteger(int=0);intget()const;MyInteger

operator+(const

MyInteger&);MyInteger

operator*(const

MyInteger&);private:intvalue;};OperatoroverloadingFunctionMyInteger

MyInteger::operator+(const

MyInteger&myint){return

MyInteger(this->value+myint.value);}MyInteger

MyInteger::operator*(const

MyInteger&myint){return

MyInteger(this->value*myint.value);}intmain(){MyIntegeri1(10),i2(25);cout<<i1.get()<<

","

<<i2.get()<<endl;MyIntegeri3;i3=i1+i2;//i3=i1.addition(i2);cout<<i3.get()<<endl;i3=i1*i2;//i3=i1.multiplication(i2);cout<<i3.get()<<endl;return0;}WhyNeedsOperatorOverloading?MyIntegervalue:int+MyInteger(int=0)+~MyInteger()+operator+(constMyInteger&):MyInteger+operator*(constMyInteger&):MyInteger+get():intconst02OperatorFunctionsOperatorFunctionsMyIntegeroperator+(constMyInteger&myint);returningtypeoperatorfunctionnameparameterlistForexample,Tooverloadanoperator,youmustdefineafunction,calledoperatoroverloadingfunction(operatorfunction).returning-typeoperatorSymbol(parameter

list)SyntaxtodefineanoperatorfunctionoperatorfunctionnameOperatorFunctionsThefollowingoperatorscanbeoverloaded.Thefollowingoperatorscannotbeoverloaded.::---scoperesolution,e.g.Date::print();?:---ternaryconditional(if-then-else),e.g.x>y?x:y;.---memberselection,e.g.day.print();.*---memberselectionthroughpointertomember,e.g.student.*nameOperatorFunctionsYoucannotoverloadalloperators.Youcannotcreateanewoperator.Onlyexistingoperatorcanbeoverloaded.Youtrytokeepthemeaningofhowtheoperatorworkswithbuilt-intypes.Operatorfunctionscanbememberfunctionsofclassesornon-member

functions.

03BinaryOperatorOverloadingBinaryOperatorsForexample,+,-,==,!=,&&Abinaryoperatorisanoperatorthatoperatesontwooperandsandmanipulatesthemtoreturnaresult.HowtoOverloadBinaryOperatorsForanybinaryoperator@,

aa@bb

MyInteger

MyInteger::operator+(MyInteger&i);MyInteger

operator+(MyInteger&i1,MyInteger&i2);Object’snames,user-definedtypeintmain{MyIntegeri1(10),i2(25),i3;i3=i1+i2;i3=i1*i2;}SyntaxtodefineabinaryoperatorfunctionIfanoperatorfunctionisdefinedasamemberfunction,

ittakesoneparameter.TherearetwowaystodefineanoperatorfunctionIfanoperatorfunctionisdefinedasanon-memberfunction,

ittakestwoparameters.aa.operator+(bb)operator+(aa,bb)HowtoOverloadBinaryOperatorsclass

MyInteger{public:MyInteger(int

v):value(v){}MyIntegeroperator+(MyInteger&);friend

MyIntegeroperator-(MyInteger&,MyInteger&);intget()const{returnvalue;}private:intvalue;};memberfunctionnon-memberfunctionintmain(){MyIntegera(13);MyIntegerb(12);MyIntegerc=b;//copyconstructora=b+c;b=b+c-a;cout<<a.get()<<b.get();return0;}MyInteger

MyInteger::operator+(MyInteger&i){MyIntegertemp(0);temp.value=this->value+i.value;returntemp;}MyIntegeroperator-(MyInteger&i1,MyInteger&i2){MyIntegertemp(0);temp.value=i1.value-i2.value;returntemp;}a=b.operator+(c)b=operator-(b.operator+(c),a)04UnaryOperatorOverloadingUnaryOperatorsForexample,++a,--a,a--,a++,a−(−b),~a,!aAnunaryoperatorisanoperatorthatactsuponasingleoperandtoproduceanewvalue.HowtoOverloadUnaryOperatorsForanyprefixunaryoperator@@aaDefinitionofprefix

increment/decrementoperatorsObject’sname，user-definedtypeintmain{MyIntegeri1(10),i2(25);++i1;--i2;cout<<(++i1).get()<<endl;}MyInteger&MyInteger::operator++();MyInteger

operator--(MyInteger&);SyntaxtodefineanunaryoperatorfunctionIfanoperatorfunctionisdefinedasamemberfunction,

itdoesnottakeanyparameter.TherearetwowaystodefineanoperatorfunctionIfanoperatorfunctionisdefinedasanon-memberfunction,

ittakesoneparameter.aa.operator++()operator--(aa)PrefixUnaryOperatorsclass

MyInteger{public:MyInteger(int);intget()const;MyInteger&operator++();//memberfunctionfriend

MyInteger

operator--(MyInteger&);//non-memberfunctionprivate:intvalue;};intmain(){MyIntegeri1(10),i2(25);cout<<i1.get()<<

","

<<i2.get()<<endl;cout<<(++i1).get()<<endl;cout<<(--i2).get()<<endl;return0;}MyInteger&MyInteger::operator++(){

this->value++;

return*this;}(i1.operator++()).get()(operator--(i2)).get()MyInteger

operator--(MyInteger&myint){

myint.value--;return

myint;}PrefixunaryoperatorsWhytoreturnthethispointer?PostfixUnaryOperatorsForanypostfixunaryoperator@aa@Definitionofpostfixincrement/decrementoperatorsObject’sname,user-definedtypeintmain(){MyIntegeri1(10),i2(25);i1++;i2++;cout<<(i1++).get()<<endl;}SyntaxtodefineanunaryoperatorfunctionIfanoperatorfunctionisdefinedasamemberfunction,

itdoesnottakeanyparameter,butidentifierint.TherearetwowaystodefineanoperatorfunctionIfanoperatorfunctionisdefinedasanon-memberfunction,

ittakesoneparameterandidentifierint.MyInteger

MyInteger::operator++(int);MyInteger

operator--(MyInteger&,int);Note:intisadummyparameteraa.operator++(int)operator--(aa,int)PostfixUnaryOperatorsintmain(){MyIntegeri1(10),i2(25);cout<<i1.get()<<

","

<<i2.get()<<endl;cout<<(i1++).get()<<endl;cout<<i1.get()<<endl;cout<<(i2--).get()<<endl;cout<<i2.get()<<endl;return0;}class

MyInteger{public:MyInteger(int);intget()const;MyInteger

operator++(int);//memberfunctionfriend

MyInteger

operator--(MyInteger&,int);private:intvalue;};(i1.operator++(int)).get()(operator--(i2,int)).get()postfixunaryoperatorsMyInteger

MyInteger::operator++(int){MyIntegertemp(0)=*this;this->value++;returntemp;}MyInteger

operator--(MyInteger&myint,int){MyIntegertemp(0)=myint;myint.value--;returntemp;}05CaseStudyCaseStudyGivenatestprogramasfollows.DefineaComplexclassaccordingtothetestprogram.a+biComplexreal:doubleimag:double+Complex(double=0,double=0)+~Complex()+Complex(constComplex&)+operator+(constComplex&):Complex+operator=(constComplex&):Complex&+operator++():Complex&+operator++(int):Complex+print():voidconstintmain(){Complexc1(2.1,4.5),c2(3.4,5.6);c1.print();c2.print();Complexc3=c1+c2;c3.print();c1=c3;c1.print();(++c3).print();(c3++).print();c3.print();return0;}DefinitionoftheComplexclassWhendoyouneedtopassavalueorareferencetoanoperatorfunction?Whendoyouneedtoreturnavalueorareferencefromanoperatorfunction?class

Complex{public:Complex(double

r=0,double

i=0);//defaultconstructorComplex(const

Complex&);//copyconstructorComplex

operator+(Complex&);//operator+Complex&operator=(Complex&);//operator=Complex&operator++();//prefixoperator++friend

Complex

operator++(Complex&,int);//postfixoperator++voidprint()const;private:doublereal,imag;};Complexreal:doubleimag:double+Complex(double=0,double=0)+~Complex()+Complex(constComplex&)+operator+(constComplex&):Complex+operator=(constComplex&):Complex&+operator++():Complex&+operator++(int):Complex+print():voidconstBinaryandUnaryOperatorFunctionsComplex

Complex::operator+(Complex&c){return

Complex(this->real+c.real,this->imag+c.imag);}class

Complex{public:Complex(double

r=0,double

i=0);//defaultconstructorComplex(const

Complex&);//copyconstructorComplex

operator+(Complex&);//operator+Complex&operator=(Complex&);//operator=Complex&operator++();//prefixoperator++friend

Complex

operator++(Complex&,int);//postfixoperator++voidprint()const;private:doublereal,imag;};Complex&Complex::operator++(){this->real++;this->imag++;return*this;}prefixComplex

operator++(Complex&c,int){Complextemp=c;c.real++;c.imag++;returntemp;}postfixComplex&Complex::operator=(Complex&c){this->real=c.real;this->imag=c.imag;return*this;}Complex::Complex(const

Complex&c){this->real=c.real;this->imag=c.imag;}ThinkOverintmain(){Complexc1(2.1,4.5),c2(3.4,5.6);c1.print();c2.print();Complexc3=c1+c2;c3.print();c1=c3;c1.print();(++c3).print();(c3++).print();c3.print();return0;}Whatisthedifferencebetweenthesetwostatements?SummaryWhyneedsoperatoroverloading?Whatdooperatorfunctionsmean?OverloadingbinaryoperatorsAbinaryoperatorcanbedefinedbyeitheranon-staticmemberfunctiontakingoneparameteroranon-memberfunction

takingtwoparameters.OverloadingunaryoperatorsPrefix:Aunaryoperatorcanbedefinedbyeitheranon-staticmemberfunctionwithoutparameteroranon-memberfunction

withoneparameters.Postfix:Aunaryoperatorcanbedefinedbyeitheranon-staticmemberfunctionwithoutparameterbutintoranon-memberfunction

withoneparametersbutint.ObjectivesTobeabletodefinemixedarithmeticofuser-definedtypesandbuilt-intypesTobeabletooverloadcombinatorialoperatorsTo

understandhowtoconvertobjectsfromuser-definedtypestobuilt-intypes01CombinatorialOperators03TypeConversion02MixedArithmetic04CaseStudy:Operators<<and>>01OverloadingCombinatorialOperatorsCombinatorialOperatorsForabuilt-intype,forexample,aisaninteger,ifa+=

5,itmeansa=a+5.Forexample,complexc1,c2;c2+=c1;Themeaningsofsomebuilt-inoperatorsaredefinedtobeequivalenttosomecombinationofotheroperatorsonthesameparameters.Canthecombinationaloperatorsworkontheuser-definedtypes?OverloadingCombinatorialOperatorsCaseStudy1Accordingtothetestprogram.Definethemeaningofoperator+=.intmain(){complexc1(20.3,11.3);complexc2;c2+=c1;c2.print();return0;}class

complex{public:complex(double

r=0.0,double

i=0.0):real(r),imag(i){}complexoperator+(complex&c);complex&operator=(const

complex&c);complex&operator+=(complex&c);voidprint()const;private:

doublereal,imag;};OverloadingCombinatorialOperatorscomplex

complex::operator+(complex&c){complextemp;temp.real=this->real+c.real;temp.imag=this->imag+c.imag;returntemp;}complex&complex::operator=(const

complex&c){if(this!=&c){this->real=c.real;this->imag=c.imag;}return*this;}complex&complex::operator+=(complex&c){*this=*this+c;return*this;}complex&complex::operator+=(complex&c){this->real+=c.real;this->imag+=c.imag;return*this;}02MixedArithmeticcomplexc1,c2(3.0,4.0);doubled=5.2;c2=c1+d;c2=d+c1;MixedArithmeticdouble(abuilt-intype)complex(user-definedtype)c1+dMemberfunction:c1.operator+(d)Non-memberfunction:operator+(c1,d)d+c1Memberfunction:d.operator+(c1)Non-memberfunction:operator+(d,c1)Mixedauser-definedtypes

withabuilt-intypeAnoperatorfunctioncanbedefinedforthemixedarithmeticofauser-definedtypeandbuilt-intype.MixedArithmeticAnoperatorfunctionmusteitherbememberofauser-definedtypesornon-membertakingatleastoneparameterofauser-definedtypes.Thisensuresthatausercannotchangethemeaningofanexpression.

MemberfunctionNon-memberfunctionintmain(){complexc1,c2(3.0,4.0);doubled=5.2;c2=c1+d;c2=d+c1;return0;}c2=c1.operator+(d)c2=operator+(d,c1)HowtoDefineMixedArithmeticclass

complex{public:complex(double

r=0.0,double

i=0.0):real(r),imag(i){}complex

operator+(double);friend

complex

operator+(double,complex&);private:doublereal,imag;};complex

complex::operator+(double

dd){return

complex(this->real+dd,this->imag);}complex

operator+(double

dd,complex&c){return

complex(c.real+dd,c.imag);}intmain(){complexc1,c2(3.0,4.0);doubled=5.2;c2=c1+d;c2=d+c1;return0;}03TypeConversionTypeConversioninti=5,j;doublea=3.4;j=i+a;doubleb=i/2;Forabuilt-intype,inti=5,j;doublea=3.4;j=i+(int)a;doubleb=(double)i/2;inti=5,j;doublea=3.4;j=i+static_cast<int>(a);doubleb=static_cast<double>(i)/2;C-styleC++styleUsingstatic_castoperatorinC++TypeConversionForauser-definedtypecomplexc1;doublea,b;b=c1+a;Thecompiler

cannotautomaticallyknowhowtoconvertuser-definedtypesintobuilt-intypesorbuilt-intypestouser-definedtypes.complexc1;complex

c2=

2.4;TypeConversionTherearetwowaysfortypeconversion:Fromabuilt-intypetoauser-definedtype.Fromauser-definedtypetoabuilt-intype.

Ifaclasshasaconstructorwhichcanbecalledwithasingleargument,thenthisconstructorbecomesconversionconstructorbecausesuchaconstructorallowsautomaticconversiontotheclassbeingconstructed.

Fromabuilt-intypetoauser-definedtypeTypeConversionclass

complex{public:complex(double

r,double

i):real(r),imag(i){}private:

doublereal,imag;};intmain(){complexc1(20.3,11.3);complexc2=10.5;return0;}complex::complex(double

r){real=r;imag=0.0;}complex(double);ConversionconstructorConversionConstructorsareconstructorsthatconverttypesofitsparameterintoatypeoftheclass.Thecompilerusestheseconstructorstoperformimplicitclass-typeconversions.Built-intypeUser-definedtypeTypeConversionTheconversionconstructorcannotspecify:animplicitconversionfromauser-definedtypetoabuilt-intype.Forexample,complex(classtype)int2.aconversionfromanewclasstoapreviouslydefinedclass(withoutmodifyingthedeclarationfortheoldclass).Forexample, complex(classtype)Date(classtype)TypeConversionoperatorT()constFromauser-definedtypetoabuilt-intypeSyntaxtodefineatypeconversionoperator

Atypeconversionoperatorinaclasscanconvertthe

classtypetoTtype

(built-intypesoruser-definedtypes).Itmustbedefinedasamemberfunction.TypeConversionclass

complex{public:complex(double

r,double

i):real(r),imag(i){}complex(doubler);operator

double()const;operator

int()const;voidprint()const;private:doublereal,imag;};complex::operator

double()const{returnreal;}complex::operator

int()const{return

static_cast<int>(real);}intmain(){complexc1=5.4;c1.print();doubled=(double)c1+3.4;cout<<d<<endl;intm=static_cast<int>(c1)+10;cout<<m<<endl;return0;}complex(classtype)Built-intypeTypeConversionclass

Test1{public:Test1(int

s){a=s;}

intget()const{returna;}private:

inta;};class

Test2{public:Test2(int

i):x(i){}

operator

Test1(){return

Test1(x);}

intget()const{returnx;}private:

intx;};Test2(class)->Test1(class)intmain(){

Test2t2Obj(20);cout<<

"Test2'sobject:"

<<t2Obj.get()<<endl;

Test1t1Obj_0=40;//willcompilecout<<

"Test1'sobject:"

<<t1Obj_0.get()<<endl;

Test1t1Obj_1=(Test1)t2Obj;//conversion->copycout<<

"Test1'sobject:"

<<t1Obj_1.get()<<endl;

return0;}04CaseStudy:OverloadingOperators<<and>>CaseStudy:OverloadingOperators<<and>>class

complex{public:complex(double

r=0,double

im=0):real(r),imag(im){}friend

ostream&operator<<(ostream&,complex&);friend

istream&operator>>(istream&,complex&);private:doublereal,imag;};intmain(){complexc1;cin>>c1;cout<<c1<<endl;return0;}Theseoperatorsmustbeoverloadedasa

globalfunction.Andifwewanttoallowthemtoaccessprivatedatamembersoftheclass,wemustmakethem

friend.

istream&operator>>(istream&in,complex&c){in>>c.real>>c.imag;

return

in;}ostream&operator<<(ostream&out,complex&c){out<<“Thecomplexis"<<c.real<<""<<c.imag<<endl;return

out;}SummaryUnderstandhowtooverloadcombinatorialoperatorsUnderstandhowtoimplementmixedarithmeticUnderstandtypeconversionsObjectivesTounderstandclasshierarchyandinheritanceTobeabletoderivenewclassesfromexistingclassesTo

beabletodefineconstructorsanddestructorsofderivedclasses01ClassHierarchiesand

Inheritance03Constructorsand

DestructorsofDerivedClasses02InheritanceandDerivedClasses04Inheritanceand

Composition01ClassHierarchiesandInheritanceClassHierarchyTherearedifferentpositionsofemployeesinacompany,i.e.secretary,managerandengineer.ThethreeclassesaredesignedbythefollowingUMLdiagram.Secretary-name:string-ID:intdepartment:stringduty:string+

print():voidconst+sendDoc():

voidManager-name:string-ID:intdepartment:stringresponsibility:string+print():voidconst+management():voidEngineer-name:string-ID:intdepartment:stringworkType:string+print():voidconst+design():voidDataabstraction1.Data–name,ID,departmentsecretary:dutymanager:responsibilityengineer:worktype2.Functions(operations)printsecretary:senddocuments

manager:managementengineer:designCaseStudy1ClassHierarchySecretary-duty:string+sendDoc():

voidManager-responsibility:string+management():voidEngineer-workType:string+design():voidEmployee-name:string-ID:intdepartment:string+print():voidconstForexample,3Dgeometric-cube,cuboidAnimal-cat,dog,cowPerson-student,teacherAbstractcommonfeaturesandputtheminaclass.Aclasshierarchyrepresentsasetofhierarchicallyorganizedconcepts.Someclassedarederivedfromcommonclasses.Suchasetofrelatedclassesistraditionallycalledaclasshierarchy.Inheritance(继承)Inheritanceisoneofthemostimportantfeatureintheobject-orientedprogramming,enablingyoutoorganizeclassesinahierarchicalform.Anewclasscaninherittheexistingclass’sdatamembersandmemberfunctionsandaddmembersofitsown.Thisprocessofcreatinganewclassfromanexistingclassisknownasinheritance.Themainadvantageofinheritanceisthereusabilityofthecode.Inheritanceallowswell-testedcodetobereusedandenableschangestomakeonceandaffectallrelevantplaces.

TypeofInheritanceTreestructureofclasshierarchyLatticestructureofclasshierarchySingleinheritanceandmultilevelinheritanceMultipleinheritanceandhybridinheritance02InheritanceandDerivedClassesHowtoImplementInheritanceManager-name:string-ID:intdepartment:string-responsibility:string+print():voidconst+management():voidEmployee-name:string-ID:intdepartment:string

+print():voidconstclass

Employee{public:intprint()const;private:stringname;intID;stringdepartment;};class

Manager{public:voidmanagement();private:Employeeemp;

stringresponsibility;};

XDoesamanagerhaveanemployee?？AmanagerisanemployeeHowtoImplementInheritanceAmanagerisanemployeeclass

Employee{public:intprint()const;private:stringname;intID;stringdepartment;};class

Manager:public

Employee{public:voidmanagement();private:stringresponsibility;};derivedclass(childclass)-anewclassbaseclass(parentclass)–anexistingclassManager-responsibility:string+management():voidEmployee-name:string-ID:intdepartment:string+print():voidconstThe

arrow

pointingupwardfromclassManagertoclassEmployeeClassManagerinheritsdatamembersandmemberfunctionsfromclassEmployee.InheritanceItisamechanism

whichonenewclassisabletoinherittheproperties(thedataandoperations)froman

existingclass.InheritanceisanimportantfeatureinOOP.Itprovidesawayforobjectstodefinerelationshipseachother.Theadvantageofinheritanceissoftwarereusability.HowtoDefineDerivedClassesclassderived_class:

publicbase_class{/*...*/};baseclassnameaccessspecifierderivedclassnameSyntaxtodefineaderivedclassclass

Employee{public:Employee(string,int,

string);intprint()const;private:stringname;intID;stringdepartment;};class

Manager:public

Employee{public:Manager(string,int,string,string);voidmanagement()const;private:stringresponsibility;};stringname;intID;stringdepartment;voidprint()const;DerivedClassesForexample,aManagerisanEmployee,sowecanwriteManagerm;Employeee=m;//okHowever,anEmployeeisnotnecessarilyaManager,soanEmployeecannotbeusedasaManager.

Employeee;Managerm=e;//errorRelationshipbetween

baseclassesandderivedclasses“is-a”Thederivedclassisabaseclass.Sothederivedclasscanbeusedasabaseclass.03ConstructorsandDestructorsofDerivedClassesDerivedClasses’Constructorsderived_constructor_name(parameters):base_constructor_name(parameters){...}InitializationlistAderivedclassinheritseverymemberofitsbaseclassexcept:itsconstructorsanddestructorsitsoverloadedoperator(=)itsfriendsSyntaxtodefinethe

constructor

of

aderivedclassDerivedClasses’ConstructionResult:thisisabaseclassthisisabaseclassthisisaderivedclassConstructorwithoutparametersclass

Employee{public:Employee(){cout<<"thisisabaseclass\n";}};class

Manager:public

Employee{public:Manager():Employee(){cout<<"thisisderivedclass.\n";}};intmain(){Employeeem;Managerma;}DerivedClasses’ConstructionConstructorswithparametersclass

Employee{public:Employee(string

n,int

no){name=n;No=no;cout<<name<<"isanemployee.\n";}private:

stringname;

intNo;};class

Manager:public

Employee{public:Manager(string

n,int

no,string

rs):Employee(n,no){cout<<"Heisalsoamanager.\n";responsibility=rs;}private:stringresponsibility;};intmain(){Employeeem("Tom",1);Managerma("Jerry",2,"sign");}Result:Tomisanemployee.Jerryisanemployee.Heisalsoamanager.DerivedClasses’DestructorsThedestructorofaderivedclassisusedtocleanupandreleasememory.Thedefinitionofderivedclass’sdestructoristhesameasitsbaseclass’s.class

Manager:public

Employee{public:Manager(string

n,int

no,string

rs):Employee(n,no){cout<<"Heisalsoamanager.\n";responsibility=rs;}~Manager(){cout<<"Managerisdestroyed.\n";}private:stringresponsibility;};DerivedClasses’ConstructorandDestructorclass

Employee{public:Employee(string

n,int