C++编程思想 答案 第五章 其他章节请点击用户名找 thinking in C++ annotated solution guidecharpter 5Word文档格式.docx

C++编程思想 答案 第五章 其他章节请点击用户名找 thinking in C++ annotated solution guidecharpter 5Word文档格式.docx

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//:

S05:

PointToMeAndYou.cpp

#include<

iostream>

usingnamespacestd;

classYou;

//Forwarddeclaration

classMe{

public:

voidProcessYou（You*p）{

cout<

<

"

ProcessingYouat"

<

p<

endl;

}

};

classYou{

voidProcessMe（Me*p）{

ProcessingMeat"

intmain（）{

Meme;

Youyou;

me.ProcessYou（&

you）;

you.ProcessMe（&

me）;

}

/*Output:

ProcessingYouat0065FDF4

ProcessingMeat0065FDFC

*/

///:

~

Whentwoclassesrefertoeachother,itisnecessarytoforward-declareatleastoneofthem,asIdidabove.Youmustonlyusepointers,ofcourse,oryou’lltrulyfindyourselfinachicken-and-eggfix.FYI:

whenclasseshavearelationship,forexample,andEmployee“has-a”Manager,itiscommontoreflectthisrelationshipbyactuallystoringapointertotheManagerobjectasamemberintheEmployeeobject,soyoudon’thavetoexplicitlypasspointersasargumentstomemberfunctionslikeIdidhere.

5-5

Createthreeclasses.Thefirstclasscontainsprivatedata,andgrantsfriendshiptotheentiresecondclassandtoamemberfunctionofthethirdclass.Inmain（）,demonstratethatalloftheseworkcorrectly.

MyFriends.cpp

classHasStuff;

//MustprecedeGoodFrienddefinition

classGoodFriend{//MustprecedeHasStuffdefinition

voidhasAccess（HasStuff*p）;

voidhasNoAccess（HasStuff*p）{

Cannotaccess"

classHasStuff{

private:

intx;

friendclassBestFriend;

friendvoidGoodFriend:

:

hasAccess（HasStuff*）;

//MustfollowHasStuffdefinition:

voidGoodFriend:

hasAccess（HasStuff*p）{

FromGoodFriend:

hasAccess:

p->

x<

//AllmethodsofBestFriendhaveaccesstoHasStuff:

x

//ThismustalsofollowtheHasStuffdefinition:

classBestFriend{

voidinitFriend（HasStuff*p）{

x=5;

voidqueryFriend（HasStuff*p）{

FromBestFriend:

HasStuffh;

BestFriendb;

b.initFriend（&

h）;

b.queryFriend（&

GoodFriendg;

g.hasAccess（&

g.hasNoAccess（&

5

Cannotaccess0065FE00

Thisisanotherexerciseinforwarddeclarations.ThedefinitionofGoodFriendrequirestheexistenceofclassHasStuff,butIcannotincludetheimplementationofGoodFriend:

hasAccess（）insitu,becauseitusesthefactthatHasStuffcontainsanintegernamedx（likewisefortheentireclassBestFriend）.Also,ifyoutriedtoaccessHasStuff:

xinGoodFriend:

hasNoAccess（）youwouldgetacompilererror.Thestatement“friendclassBestFriend”insideofHasStuffissimultaneouslyaforwarddeclarationandafrienddeclaration,otherwiseIwouldhavehadtoforward-declareBestFriendbeforethedefinitionofHasStuff（butI’mlazy）.

5-6

CreateaHenclass.Insidethis,nestaNestclass.InsideNest,placeanEggclass.Eachclassshouldhaveadisplay（）memberfunction.Inmain（）,createaninstanceofeachclassandcallthedisplay（）functionforeachone.

NestedFriends.cpp

classHen{

voiddisplay（）{

Hen:

display\n"

;

classNest{

public:

Nest:

classEgg{

Egg:

};

Henh;

Hen:

Nestn;

Egge;

h.display（）;

n.display（）;

e.display（）;

display

NestandEggarejustlikenormalclassesexcepttheyresideinthescopeofotherclassesinsteadoftheglobalscope,whichexplainstheneedfortheexplicitqualificationviathescoperesolutionoperator.Also,HenhasnoaccessrightstoanyprivatemembersofNestorEgg,nordoesNesthaveanyrightstoEgg’sprivatemembers（iftherewereany–seethenextexercise）.

5-7

ModifyExercise6sothatNestandEggeachcontainprivatedata.Grantfriendshiptoallowtheenclosingclassesaccesstothisprivatedata.

friendclassHen;

inty;

friendclassNest;

display:

y<

voidinitEgg（Egg*e）{

e->

y=2;

x<

voidinitNest（Nest*n）{

n->

x=1;

h.initNest（&

n）;

n.initEgg（&

e）;

1

2

InthisexampleIhadtomovetheimplementationofHen:

display（）pastthenestedclassEgg,becauseitaccessmembersofEgg.Thesamereasoningappliestotheinit-functionsabove.

5-8

Createaclasswithdatamembersdistributedamongnumerouspublic,private,andprotectedsections.AddamemberfunctionshowMap（）thatprintsthenamesofeachofthesedatamembersandtheiraddresses.Ifpossible,compileandrunthisprogramonmorethanonecompilerand/orcomputerand/oroperatingsystemtoseeiftherearelayoutdifferencesintheobject.

Here’sasamplefortwoparticularcompilers:

MapMembers.cpp

classMapped{

protected:

intz;

voidshowMap（）{

xisat"

&

yisat"

y<

zisat"

z<

Mappedm;

m.showMap（）;

//CompilerA:

xisat0065FDF8

yisat0065FDFC

zisat0065FE00

//CompilerB:

xisat0064FDEC

yisat0064FDF0

zisat0064FDF4

5-9

CopytheimplementationandtestfilesforStashinChapter4sothatyoucancompileandtestStash.hinthischapter.

5-10

PlaceobjectsoftheHenclassfromExercise6inaStash.Fetchthemoutandprintthem（ifyouhavenotalreadydoneso,youwillneedtoaddHen:

print（））.

5-11

CopytheimplementationandtestfilesforStackinChapter4sothatyoucancompileandtestStack2.hinthischapter.

5-12

PlaceobjectsoftheHenclassfromExercise6inaStack.Fetchthemoutandprintthem（ifyouhavenotalreadydoneso,youwillneedtoaddHen:

5-13

ModifyCheshireinHandle.cpp,andverifythatyourprojectmanagerrecompilesandrelinksonlythisfile,butdoesn’trecompileUseHandle.cpp.

5-14

CreateaStackOfIntclass（astackthatholdsints）usingthe“Cheshirecat”techniquethathidesthelow-leveldatastructureyouusetostoretheelementsinaclasscalledStackImp.ImplementtwoversionsofStackImp:

onethatusesafixed-lengtharrayofint,andonethatusesavector<

int>

.Haveapresetmaximumsizeforthestacksoyoudon’thavetoworryaboutexpandingthearrayinthefirstversion.NotethattheStackOfInt.hclassdoesn’thavetochangewithStackImp.

Here’stheStackOfIntclass:

StackOfInt.h

cstddef>

//forsize_t

climits>

//forINT_MIN

//VC++doesn’tputsize_tinstd:

#ifndef_MSC_VER

usingstd:

size_t;

#endif

structStackImp;

//Incompletetypedeclaration

structStackOfInt{

enum{STKERROR=INT_MIN};

voidinit（）;

voidcleanup（）;

intpush（int）;

intpop（）;

inttop（）;

size_tsize（）;

StackImp*pImpl;

//The“smile”

TodoCheshireCat,IjustdeclaretheStackImpclass（thismakesitan“incomplete”type）,anddeclareapointertoitasamemberofStackOfInt.TheimplementationsofStackOfInt’smemberfunctionswillusetheinternalsofStackImpviapImpl,soIhavetodefinethemethodbodiesinaseparate.cppfile（otherwisewe’renothidinganything!

）.Here’sthe.cppfileforthearrayversion:

StackOfInt1.cpp{O}

//Usesanarraytoi