C++面向对象程序设计双语教程（第3版）课件 class 13-Polymorphism、class 14-template

ObjectivesTounderstandthemechanismsofstaticanddynamicpolymorphismTobeabletodeclarevirtualfunctionsandknowhowtousethemTobeabletodefineanabstractbaseclass01WhatisPolymorphism?04AbstractBaseClasses02DynamicPolymorphismandVirtualFunctions03UnderstandingofVirtualFunctions05InheritingInterfaceandImplementation01WhatisPolymorphism?Polymorphismforanaddition(+)operator,a+

bi+

jcomplex1+complex2foraprint

function, voidprint(int);voidprint(int,char*);Forexample,Whatispolymorphism?Wordmeaning--manyformsPolymorphismmeansthatsomecodes(functions),operatorsorobjectsbehavedifferentlyindifferentcontextsusingauniformform.PolymorphismisoneofOOPkeyfeatures.Polymorphism-BindingBindingisanassociation,suchasbetweenidentifiers(variablesorfunctionnames)andoperations(atypeorthespecificfunctionbody).Allfunctionshaveauniqueaddress.So,whenthecompilerencountersafunctioncall,itreplacesthefunctioncallwithamachinelanguageinstructionthattellstheCPUtojumptotheaddressofthefunction.Polymorphism-BindingTherearetwotypesofbindingaccordingtothetimeatwhichabindingtakesplace:(1)Compile-timebinding(calledstatic

binding,earlybinding)

–staticpolymorphism(2)Run-timebinding(calleddynamicbinding,latebinding)–dynamicpolymorphismStaticBinding(Compile-Time)–StaticPolymorphismclass

baseClass{public:voidf(){cout<<"CallingbaseClass\n";}};class

derivedClass:public

baseClass{public:voidf(){cout<<"CallingderivedClass\n";}};intmain(){baseClassone;one.f();derivedClasstwo;two.f();return0;}Staticbindingmeansthecompilerisabletodirectlyassociatetheidentifiername(suchasafunctionorvariable)withamachineaddress.Result:CallingbaseClassCallingderivedClassStaticBinding–StaticPolymorphismResult:CallingbaseClassCallingbaseClassclass

baseClass{public:voidf(){cout<<"CallingbaseClass\n";}};class

derivedClass:public

baseClass{public:voidf(){cout<<"CallingderivedClass\n";}};voidfn(baseClass&bc){bc.f();}intmain(){baseClassone;fn(one);derivedClasstwo;fn(two);return0;}A

top-level

functionwithaparameterofbaseclassreferenceorpointeri.e.referredtoasthederived-to-baseconversion02DynamicPolymorphismandVirtualFunctionsDynamicBinding(Run-Time)–DynamicPolymorphismResult:CallingbaseClassCallingderivedClassclass

baseClass{public:virtual

voidf(){cout<<"CallingbaseClass\n";}};class

derivedClass:public

baseClass{public:voidf(){cout<<"CallingderivedClass\n";}};voidfn(baseClass&bc){bc.f();}intmain(){baseClassone;fn(one);derivedClasstwo;fn(two);return0;}DynamicBinding

referstolinkingafunctioncalltothecodethatwillbeexecutedonlyatruntime.Thecodeassociatedwiththeproceduredosenotknowuntiltheprogramisexecuted.virtualfunctionVirtualFunctionsShape+volume():int+print():voidCube-edge:int+volume():int+print():voidCuboidlength:intwidth:intheight:int+volume():int+print():voidCaseStudyDefineclassescubeandcuboidaccordingtothegivenUMLdiagram.Cube-edge:int+volume():int+print():voidCuboidlength:intwidth:intheight:int+volume():int+print():voidVirtualFunctionsclass

Shape{public:Shape(){}virtual

intvolume(){cout<<"Shape'svolume.\n";return0;}virtual

voidprint(){cout<<"Shape’sprint.\n";}};class

Cube:public

Shape{public:Cube(int

e):edge(e){}virtual

intvolume(){cout<<"Cube’svolume\n";returnedge*edge*edge;}voidprint(){cout<<edge<<endl;}private:int

edge;};class

Cuboid:public

Shape{public:Cuboid(int

l,int

w,int

h):length(l),width(w),height(h){}virtual

intvolume(){cout<<"Cubiod’svolume\n";returnlength*width*height;}voidprint(){cout<<length<<width<<height<<endl;}private:intlength,width,height;};voidfn(Shape&

s){

s.print();cout<<s.volume();}intmain(){Cubec1(10);Cuboidc2(10,20,30);fn(&c1);fn(&c2);return0;}intmain(){Cubec1(10);Cuboidc2(10,20,30);fn(c1);fn(c2);return0;}voidfn(Shape*s){

s->print();cout<<s->volume();}ExtensibilityShape+volume():int+print():voidCube-edge:int+volume():int+print():voidCuboidlength:intwidth:intheight:int+volume():int+print():voidSphere-radius:int+volume():int+print():voidBenefitofusingvirtualfunctionsExtensibilityclass

Sphere:public

Shape{public:Sphere(int

r):radius(r){}virtual

intvolume(){

cout<<"Sphere’svolume\n";

return3.14*(double)4*(double)radius*radius*radius/3;}virtual

voidprint(){cout<<radius<<endl;}private:intradius;};voidfn(Shape*s){

s->print();cout<<s->volume();}intmain(){Cubec1(10);Cuboidc2(10,20,30);Spheres(10);fn(&c1);fn(&c2);fn(&s);return0;}03UnderstandingofVirtualFunctionsTheWorkingPrincipleofVirtualFunctionsintmain(){Cubec1(10);cout<<"sizeofc1"<<sizeof(c1)<<endl;Cuboidc2(10,20,30);cout<<"sizeofc2"<<sizeof(c2)<<endl;return0;}(32-bitcompiler)sizeofc18sizeofc216VirtualFunctionTable—VTABLEThecompilercreatesasinglevirtualfunctiontable(VTABLE)foreachclassthatcontainsvirtualfunctions.ThecompileplacestheaddressesofvirtualfunctionsforthoseclassesintheVTABLE.Apointer(vptr)isplacessecretlyineachclasswithvirtualfunctions.ItpointstotheVTABLEforobjects.addressaddressaddressConversionsandInheritancevoidfn(Shape&

s){

s.print();cout<<s.volume();}intmain(){

Cubec1(10);

Cuboidc2(10,20,30);fn(c1);fn(c2);

return0;}intmain(){

Cubec1(10);

Shape&

s=c1;

s.print();cout<<s.volume();

Cuboidc2(10,20,30);

s=c2;

s.print();cout<<s.volume();return0;}derived-to-baseUnderstandingconversionsbetweenbaseandderivedclassesisessentialtounderstandinghowobject-orientedprogrammingworks.ConversionsandInheritancevoidfn(Shape*s){

s->print();cout<<s->volume();}intmain(){

Cubec1(10);

Cuboidc2(10,20,30);fn(&c1);fn(&c2);

return0;}intmain(){

Cubec1(10);

Shape*

s=&c1;

s->print();cout<<s->volume();

Cuboidc2(10,20,30);

s=&c2;

s->print();cout<<s->volume();

return0;}derived-to-baseConversionsandInheritancevoidmain(){

Shape

s;Cube

&c1=s;//errorCube

*c2=s;//error}Thisresultsinthatwemightattempttousec1orc2tousemembersthatdonotexistinShape.Thefactthatwecanbindareference(orpointer)toabase-classtypetoaderivedobjecthasacruciallyimportantimplication:Whenweuseareference(orpointer)toabase-classtype,wedon’tknowtheactualtypeoftheobjecttowhichthepointerorreferenceisbound.Thatobjectcanbeanobjectofthebaseclassoritcanbeanobjectofaderivedclass.ConversionsandInheritanceintmain(){

Cubec1(10);

Shape

s=c1;}ShapeCube’sdataCubeMemoryBecausetheCubeisignored,wesaythattheCubeportionofShapeissliceddown.intmain(){

Cubec1(10);

Shape

s;s=c1;}Shape(constShape&)Shape&operator=(constShape&)Theautomaticderived-to-baseconversionappliesonlyforconversionstoareferenceorpointertype.VirtualDectructorResult:ConstructingbaseclassConstructingderivedclassDosthinBase!BaseDestroyedConstructorcannotbevirtualfunction,butdestructoralwaysbevirtualfunction.class

Base{public:Base(){cout<<"Constructingbaseclass\n";}~Base(){cout<<"BaseDestroyed\n";}voidDoSomething(){cout<<"DosthinBase!\n";}};class

Derived:public

Base{public:Derived(){cout<<"Constructingderivedclass\n";}~Derived(){cout<<"Deriveddestroyed\n";}voidDoSomething(){cout<<"DosthinDerived!\n";}};intmain(){//upcastBase*pBase=new

Derived;pBase->DoSomething();deletepBase;return0;}BaseclasspointertothederivedclassobjectVirtualDectructorclass

Base{public:Base(){cout<<"Constructingbaseclass\n";}~Base(){cout<<"BaseDestroyed\n";}virtual

voidDoSomething(){cout<<"DosthinBase!\n";}};class

Derived:public

Base{public:Derived(){cout<<"Constructingderivedclass\n";}~Derived(){cout<<"Deriveddestroyed\n";}voidDoSomething(){cout<<"DosthinDerived!\n";}};intmain(){Base*pBase=new

Derived;//upcastpBase->DoSomething();deletepBase;}class

Base{public:Base(){cout<<"Constructingbaseclass\n";}virtual~Base(){cout<<"BaseDestroyed\n";}virtual

voidDoSomething(){cout<<"DosthinBase!\n";}};class

Derived:public

Base{public:Derived(){cout<<"Constructingderivedclass\n";}~Derived(){cout<<"Deriveddestroyed\n";}voidDoSomething(){cout<<"DosthinDerived!\n";}};Result:(withvirtual)ConstructingbaseclassConstructingderivedclassDosthinDerived!BaseDestroyedResult:ConstructingbaseclassConstructingderivedclassDosthinDerived!DeriveddestroyedBaseDestroyed04AbstractBaseClassesAbstractBaseClassesSomeclassesrepresentabstractconceptsforwhichobjectscannotexist,thatis,theycannotbeinstantiated,becauseatleastonefunctionintheseclassesdonotknowwhattobeimplemented.However,theyexistsextensivelyforinheritance,andmostlyusedasabaseclass.Theseclassesarecalledabstractbaseclasses.class

Shape{public:Shape(){}virtual

intvolume();virtual

voidprint();};AbstractBaseClassesAclasswhichcontainsoneormorepurevirtualfunctioniscalledabstractbaseclass.class

Shape{public:Shape(){}virtual

intvolume()=0;virtual

voidprint()=0;};PurevirtualfunctionAbstractbaseclassApurevirtualfunction

isavirtualfunctionwhichcontainsnodefinitioninthebaseclass.Youdeclareapurevirtualfunctionbyusingapurespecifier(=0)inthedeclarationofavirtualmemberfunctionintheclassdeclaration.AbstractBaseClassesclass

Shape{public:Shape(){}virtual

intvolume()=0;virtual

voidprint()=0;};intShape::volume(){return

0;}voidShape::print(){}wecanprovideadefinitionforapurevirtual.However,thefunctionbodymustbedefinedoutsidetheclass.Thatis,wecannotprovideafunctionbodyinsidetheclassforafunctionthatis=0.AbstractBaseClassesShapes;//error–cannotbeinstantiatedShape*s;//okShape&s;//okAnobjectpointerAnobjectreferenceYoucannotcreateanobjectofanabstractclasstype;However,youcanusepointers

orreferencestoabstractclasstypes.AbstractBaseClassesclass

Shape{public:Shape(){}virtual

intvolume()=0;};class

Cube:public

Shape{public:Cube(int

e):edge(e){}intvolume(){

cout<<"Cube’svolume\n";

returnedge*edge*edge;}private:

intedge;};class

Cuboid:public

Shape{public:

Cuboid(int

l,int

w,int

h):

length(l),width(w),height(h){}

intvolume(){

cout<<"Cubiod’svolume\n";

returnlength*width*height;}private:

intlength,width,height;};intmain(){Shape*s;Cubec1(10);Cuboidc2(10,20,30);fn(&c1);fn(&c2);return0;}voidfn(Shape*s){

cout<<s->volume();}05InheritingImplementationand

Inheriting

InterfaceMemberFunctionsandInheritancebase+f():int+g():voidderived+f():intDistinguishbetweeninheritinginterfaceandinheritingimplementation.Interface-Overriding-VirtualfunctionsImplementation-

MemberfunctionsoftheclassesThememberfunctionsofabaseclasscanbeinheritedbyitsderivedclassintwoways:(1)Whenaderivedclassneedstobeabletoprovideitsowndefinitionforoperations,thederivedclassneedstooverridethedefinitionofthoseinheritedfromthebaseclass-interface(2)itsderivedclassonlyinheritthosewithoutanychange-implementationOverloadingandOverridingclass

Base{public:virtual

intf()const{cout<<"Base::f()\n";return1;}virtual

voidf(string

s)const{cout<<s<<"isaparameterintheBaseclass\n";}virtual

voidg()const{cout<<"Base::g()\n";}};class

Derived1:public

Base{public:voidg()const{cout<<"Overridingg()inDerived1\n";}};intmain(){Derived1d1;intx=d1.f();d1.f("hello");d1.g();return0;}Result:Base::f()HelloisaparameterintheBaseclassOverridingg()inDerived1OverloadingandOverridingclass

Base{public:virtual

intf()const{cout<<"Base::f()\n";return1;}virtual

voidf(string

s)const{cout<<s<<"isaparameterintheBaseclass\n";}virtual

voidg()const{cout<<"Base::g()\n";}};class

Derived1:public

Base{public:voidg()const{cout<<"Overridingg()inDerived1\n";}virtual

intf()const{cout<<“Dervied1::f()\n";return1;}};intmain(){Derived1d1;intx=d1.f();d1.f("hello");//errord1.g();return0;}nomatchingfunctionforcallto'Derived1::f(constchar[6])

d1.Base::f("hello");//okAderivedclassmemberwiththesamenameasamemberofthebaseclasshidesthedirectuseofthebaseclassmember.class

Base{public:virtual

intf()const{cout<<"Base::f()\n";return1;}virtual

voidf(string

s)const{cout<<s<<"isaparameterintheBaseclass\n";}};OverloadingandOverridingclass

Base{public:virtual

voidg()const{cout<<"Base::g()\n";}};class

Derived1:public

Base{public:voidg()constoverride{cout<<"Overridingg()inDerived1\n";}};Overriding(Virtualfunctions)inderivedclassAfunctionfromaderivedclasswiththesamename,thesamesetofparametertypesandthesamereturningtypeasavirtualfunctioninabaseclass.FunctionoverloadinginbaseclassorderivedclassAnumberoffunctionswiththesamenameanddifferenttypesand/ornumbersofparametersintheargumentlistisreferredasfunctionoverloading.MemberFunctionsandInheritanceAderivedclassinheritseverymemberofitsbaseclassexcept:itsconstructorsanddestructorsitsoverloadedoperator(=)itsfriendsPolymorphismStaticbinding(compile-timebinding)-staticpolymorphism

C++matchedafunctioncallwiththecorrectfunctiondefinitionatcompiletime,e.g.overloadingfunctions,overloadingoperatorsDynamicbinding(run-timebinding)-dynamicpolymorphismThebindingoccursatprogramexecutiontime,thatis,thecompilermatchesafunctioncallwiththecorrectfunctiondefinitionatruntime,e.g.virtualfunctionsPolymorphismPolymorphismStaticBindingOperatorOverloadingCompileTimeDynamicBindingRunTimeFunctionOverloadingVirtualFunctionSummaryBeabletoknowwhatpolymorphismisBeabletodistinguishbetweenstaticbindinganddynamicbindingBeabletodefineavirtualfunctionBeabletounderstandabstractandconcertclassesBeabletothekeyfeaturesinobject-orientedprogrammingaredataabstraction,encapsulation,inheritance,anddynamicbindingObjectivesTounderstandthepurposeofgenericprogrammingToknowthemechanismoftemplatesTobeabletodefinefunctiontemplatesandinstantiatefunctiontemplatesTobeabletodefineclasstemplatesandinstantiateclasstemplates01IntroductiontoTemplates04ClassTemplates02FunctionTemplates03FunctionTemplateInstantiation05ClassTemplateInstantiation01IntroductiontoTemplatesWhatisaTemplate?Imaginethatwewanttowriteafunctiontofindthemaximumoneoftwovalues.Inpractice,we’dwanttodefineseveralsuchfunctions,eachofwhichwillfindthemaximumvalueofagiventype.CasestudyintmaxV(int

x,int

y){return(x>y)?x:y;}charmaxV(char

x,char

y){return(x>y)?x:y;}doublemaxV(double

x,double

y){return(x>y)?x:y;}#definemaxV(x,

y)((x>y)?x:y)Problem:Macropresentsthepossibilityforserioussideeffects:notypechecking,repetitiveoperationsandsoon.intmain(){inti=5,j=3;cout<<maxV(++i,j);return0;}Result:7TmaxV(Tx,Ty){return(x>y)?x:y;}Result:6TheConceptofTemplatesTemplatemechanismallowsatypetobeaparameterinthedefinitionofaclassorafunction.TmaxV(Tx,Ty){return(x>y)?x:y;}Templatesprovideasimplewaytorepresentawiderangeofgenericconceptsandsimplewaystocombinethem.Templatesarethefoundationforgenericprogramming.Atemplateisablueprintorformulaforcreatingclassesorfunctions.

TemplatesareoneofC++’scapabilitiesforsoftwarereusability.02FunctionTemplatesFunctionTemplatestemplate<typenameidentifier>,ortemplate<classidentifier>function_declaration(orfunction_definition);template<classT>TmaxV(Tx,Ty){return(x>y)?x:y;}Keywordtemplate<typenameT>TmaxV(Tx,Ty){return(x>y)?x:y;}typeidentifierintmaxV(int

x,int

y){return(x>y)?x:y;}charmaxV(char

x,char

y){return(x>y)?x:y;}doublemaxV(double

x,double

y){return(x>y)?x:y;}templateparameterlistkeywordCasestudySyntaxtodefineafunctiontemplateFunctionTemplatesAfunctiontemplatedefinesafamilyoffunctionsthatcanoperatewith

generictypes.Thisallowsustocreateafunctiontemplatewhosefunctionalitycanbeadaptedtomorethanonetypewithoutrepeatingtheentirecodeforeachtype.03FunctionTemplateInstantiationFunctionTemplatesInstantiationtemplate<typename

T>TmaxV(Tx,Ty);//declarationintmain(){cout<<maxV(3,4)<<endl;cout<<maxV(3.4,67.8)<<endl;cout<<maxV('s','x')<<endl;return0;}template<typename

T>//definitionTmaxV(T

x,T

y){return(x>y)?x:y;}Functiontemplateinstantiationfunction_name<type>(arguments);cout<<maxV<int>(3,4);cout<<maxV<double>(3.4,67.8);cout<<maxV<char>('s','x')Functiontemplateinstantiationisacreationof

aconcretefunction.FunctionTemplatesInstantiationWhenwecallafunctiontemplate,thecompiler(ordinarily)usestheargumentsofthecalltodeducethetemplateparameter(s)(T)forus.cout<<maxV(3,4)<<endl;cout<<maxV(3.4,67.8)<<endl;cout<<maxV('s','x')<<endl;Nocodeisgeneratedfromasourcefilethatcontainsonlytemplatedefinitions.Inorderforanycodetoappear,atemplatemustbeinstantiated:thetemplateargumentsmustbedeterminedsothatthecompilercangenerateanactualfunction.FunctionTemplateswithdifferentTypeParameterstemplate<typename

T1,typename

T2>T1getMin(T1

x,T2

y){return

x<y?x:(T1)y;}intmain(){inti=9,j=6;doublea=8.3,b=7.8;cout<<getMin(i,a);return0;}cout<<getMin<int,double>(i,a);template<typename

T1,T2>//errorT1getMin(T1

x,T2

y){return

x<y?x:(T1)y;}FunctionTemplatesandOverloadingBothoftheymakecodesmorecompactandconvenient.Functionoverloadingisnormallyusedtoperformsimilaroridenticaloperationsondifferenttypesofdata.Functiontemplates

areusedtoperformidenticaloperationsondifferenttypesofdata.FunctionTemplates

Overloadingtemplate<typename

T>voidSwap(T&x,T&y);voidSwap(int&x,int&y);intmain(){inti=9,j=6;doublea=8.3,b=7.8;chars='4',t='5';Swap(i,j);Swap(a,b);Swap(s,t);return0;}template<typename

T>voidSwap(T&x,T&y){Ttemp;temp=x;x=y;y=temp;cout<<"Calloftemplate\n";}voidSwap(int&x,int&y){inttemp;temp=x;x=y;y=x;cout<<"Calloffunction\n";}Result:CalloffunctionCalloftemplateCalloftemplateWhenanon-templatefunctionprovidesanequallygoodmatchforacallasafunctiontemplate,thenon-templateversionispreferred.FunctionTemplates

OverloadingTemplate<typenameT>TgetMin(Tp1,Tp2);TgetMin(Tp1,Tp2,Tp3);Template<typenameT>TgetMin(Tp1,Tp2);intgetMin(intp1,intp2);Wecandeclareseveralfunctiontemplateswiththesamenameandevendeclareacombinationoffunctiontemplatesandordinaryfunctionswiththesamename.Thecompileralwaysmatchesfirstfunctionprototypes(exactlymatching),andthenfunctiontemplates.FunctionTemplates

Overloadingtemplate<typenameT>TgetMax(Tx,Ty){cout<<"callingtemplate\n";return(x>y)?x:y;}intgetMax(inti,intj){cout<<"callingafunctionwithinttype\n";return(i>j)?i:j;}intgetMax(doubled,inti){cout<<"callingafunctionwithadoubletype\n";return(d>i)?(int)d:i;}constintn=7;intmain(){inti=5,j=6;doublea=8.3,b=7.8;charc1='a',c2='b';cout<<getMax(i,j)<<endl;cout<<getMax(c1,c2)<<endl;cout<<getMax(a,b)<<endl;cout<<getMax(n,i)<<endl;cout<<getMax('a',1)<<endl;cout<<getMax(2.7,4)<<endl;return0;}123112232FunctionTemplatesResult:callingafunctionwithinttype6callingtemplatebcallingtemplate8.3callingafunctionwithinttype7callingafunctionwithinttype97callingafunctionwithadoubletype404ClassTemplatesClassTemplatesStackisakindofdatastructurewithLIFO(lastin,firstout).Ithastwoprincipaloperations:pushandpop.CasestudyStack+Stack()+~Stack()-IsEmpty():bool-IsFull():bool+push(int&):void+pop():int+peak():int+getSize():intconst-element:int*size:intconst-top:intClassTemplatesclass

Stack{public:Stack();~Stack();voidpush(int&i);intpop();

intpeak();intgetSize()const;private:boolIsEmpty();boolIsFull();const

intsize;int*element;inttop;};Stack+Stack()+~Stack()-IsEmpty():bool-IsFull():bool+push(int&):void+pop():int+peak():int+getSize():intconst-element:int*size:intconst-top:intStack::Stack():size(5),top(0){element=new

int[size];}Stack::~Stack(){delete[]element;}bool

Stack::IsEmpty(){return--top==-1;}bool

Stack::IsFull(){returntop>=size?true:false;}void

Stack::push(int&i){if(!IsFull())element[top++]=i;elsethrow-1;}int

Stack::pop(){if(IsEmpty())throw-2;returnelement[top];}int

Stack::peak(){returnelement[top-1];}int

Stack::getSize()const{returntop;}ClassTemplatesintmain(){Stackst;try{for(inti=0;i<4;i++)st.push(i);cout<<

"----------------\n";cout<<st.getSize()<<st.peak()<<endl;intnum=st.getSize()+1;for(inti=0;i<num;i++)cout<<st.pop()<<

"";}catch(inte){if(e==-1)cout<<

"Thestackisfull.\n";if(e==-2)cout<<

"Thestackisempty.\n";}}template<typename

T>class

Stack{public:Stack();~Stack();voidpush(T&i);Tpop();Tpeak();intgetSize()const;private:boolIsEmpty();boolIsFull();const

intsize;T*element;inttop;};Definitionof

aClassTemplatetemplate<classT>Tisagenerictype(typeparameter)Defineaclassasatemplate.Thisclassiscalledclasstemplate.Typeparameterintheclassmaybedatamembers,andmemberfunctions’parameters,andreturningvalueClassTemplatetemplate<typename

T>Stack<T>::Stack():size(5),top(0){element=new

T[size];}template<typename

T>Stack<T>::~Stack(){delete[]element;}template<typename

T>bool

Stack<T>::IsEmpty(){return--top==-1;}template<typename

T>bool

Stack<T>::IsFull(){returntop<size?true:false;}template<typename

T>void

Stack<T>::push(T&i){if(IsFull())element[top++]=i;elsethrow-1;}template<typename

T>T

Stack<T>::pop(){if(IsEmpty())throw-2;returnelement[top];}template<typename

T>T

Stack<T>::peak(){returnelement[top-1];}template<typename

T>int

Stack<T>::getSize()const{returntop;}05ClassTemplateInstantiationClassTemplateInstantiationintmain(){Stack<int>st;try{for(inti=0;i<4;i++)st.push(i);cout<<

"----------------\n";cout<<st.getSize()<<st.peak()<<endl;intnum=st.getSize()+1;for(inti=0;i<num;i++)cout<<st.pop()<<

"";}catch(inte){if(e==-1)cout<<

"Thestackisfull.\n";if(e==-2)cout<<

"Thestackisempty.\n";}}Classtemplateisinstantiated.st

isatemplateclassobjectTheprocessofgeneratingaconcreteclassfromatemplatedefinitionandtemplateargumentsisoftencalledclass

templateinstantiation.ClassTemplateInstantiationclass

A{public:A()=default;A(int

x):a(x){}friend

ostream&operator<<(ostream&o,A&obj){o<<obj.a;

returno;}private:inta;};intmain(){Stack<A>stObj;try{cout<<

"objectsarepushedintoastackonebyone.\n";for(inti=0;i<4;i++){Aobj=A(i);stObj