完整word版C++编程思想 答案 第十四章 其他章节点击用户名找 thinking in C+Word文档下载推荐.docx

完整word版C++编程思想 答案 第十四章 其他章节点击用户名找 thinking in C+Word文档下载推荐.docx

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<

"

A:

:

A（）\n"

;

}

};

classB{

B（）{cout<

B:

B（）\n"

classC:

publicA{

Bb;

intmain（）{

Cc;

/*Output:

A（）

B（）

*/

///:

~

The“parts”ofaCobjectareautomaticallyconstructed,inheritedsub-objectsfirst,followedbycontainedobjects.

14-4

Createathree-levelhierarchyofclasseswithdefaultconstructors,alongwithdestructors,bothofwhichannouncethemselvestocout.Verifythatforanobjectofthemostderivedtype,allthreeconstructorsanddestructorsareautomaticallycalled.Explaintheorderinwhichthecallsaremade.

HierarchyConstruction.cpp

~A（）{cout<

~A（）\n"

classB:

~B（）{cout<

~B（）\n"

publicB{

C（）{cout<

C:

C（）\n"

~C（）{cout<

~C（）\n"

C（）

~C（）

~B（）

~A（）

Anobject’s“parts”arealwaysconstructedbeforetheobjectitself.Applyingthisprinciplerecursivelyrequiresthatthesub-objectatthetopofthehierarchymustbecreatedfirst.Destructionisalwaysthereverseorderofconstruction.

（Exercises14-5through14-8arelefttothereader.）

14-5

InCombined.cpp,createaclassDthatinheritsfromBandhasamemberobjectofclassC.Addcodetoshowwhentheconstructorsanddestructorsarebeingcalled.

14-6

ModifyOrder.cpptoaddanotherlevelofinheritanceDerived3withmemberobjectsofclassMember4andMember5.Tracetheoutputoftheprogram.

14-7

InNameHiding.cpp,verifythatinDerived2,Derived3,andDerived4,noneofthebase-classversionsoff（）areavailable.

14-8

ModifyNameHiding.cppbyaddingthreeoverloadedfunctionsnamedh（）toBase,andshowthatredefiningoneoftheminaderivedclasshidestheothers.

14-9

InheritaclassStringVectorfromvector<

void*>

andredefinethepush_back（）andoperator[]memberfunctionstoacceptandproducestring*.Whathappensifyoutrytopush_back（）avoid*?

StringVector.cpp

//{-msc}VC++onlyfakesreinterpret_cast

vector>

string>

cstddef>

//Forsize_t

classStringVector:

publicvector<

{

voidpush_back（string*s）{

vector<

push_back（s）;

}

string*&

operator[]（size_tn）{

returnreinterpret_cast<

string*>

（vector<

operator[]（n））;

conststring*operator[]（size_tn）const{

conststring*>

StringVectorv;

strings1（"

live"

）,s2（"

long"

）,s3（"

and"

）,s4（"

prosper"

）;

v.push_back（&

s1）;

s2）;

s3）;

s4）;

for（size_ti=0;

i<

v.size（）;

++i）

cout<

*v[i]<

endl;

//void*p=&

s1;

//v.push_back（p）;

//error

live

long

and

prosper

Theproblemwiththecommented-outpush_back（）aboveisthatthereisnoimplicitconversionfromavoid*toanyothertype,asthereisinC.ThismakesStringVectortype-safe.NotethatIoverloadedbothversionsofoperator[]（constandnon-const）.

Ifyou’vedoneanyamountofreadingonobject-orientedprogramminginC++,youprobablyhavelearnedthatyoushouldneveroverrideanon-virtualfunctionfromapublicly-inheritedclass（seeforexample,ScottMeyers“EffectiveC++”,Item37）.Thestandardcontainerssuchasvectorhavenovirtualfunctionsatall,sotheremustbeabetterwaytodefineStringVector.TheBetterWayistouseprivateinheritance,andprovideaccesstotheinheritedfunctionsasthefollowingversionillustrates.

privatevector<

usingvector<

size;

Privateinheritancecombinedwithtemplatesmakesbuildingsuchtype-safecontainersfairlysimple.（SeeChapter16andVolume2）.

（Exercises14-10through14-13arelefttothereader.）

14-10

Writeaclasscontainingalongandusethepsuedo-constructorcallsyntaxintheconstructortoinitializethelong.

14-11

CreateaclasscalledAsteroid.UseinheritancetospecializethePStashclassinChapter13（PStash.h&

PStash.cpp）sothatitacceptsandreturnsAsteroidpointers.AlsomodifyPStashTest.cpptotestyourclasses.ChangetheclasssoPStashisamemberobject.

14-12

RepeatExercise11withavectorinsteadofaPStash.

14-13

InSynthesizedFunctions.cpp,modifyChesstogiveitadefaultconstructor,copy-constructor,andassignmentoperator.Demonstratethatyou’vewrittenthesecorrectly.

14-14

CreatetwoclassescalledTravelerandPagerwithoutdefaultconstructors,butwithconstructorsthattakeanargumentoftypestring,whichtheysimplycopytoaninternalstringvariable.Foreachclass,writethecorrectcopy-constructorandassignmentoperator.NowinheritaclassBusinessTravelerfromTravelerandgiveitamemberobjectoftypePager.Writethecorrectdefaultconstructor,aconstructorthattakesastringargument,acopy-constructor,andanassignmentoperator.

BusinessTraveler.cpp

classTraveler{

stringstr;

Traveler（conststring&

s）:

str（s）{}

Traveler（constTraveler&

t）:

str（t.str）{}

Traveler&

operator=（constTraveler&

t）{

if（this!

=&

t）

str=t.str;

return*this;

stringgetString（）const{

returnstr;

classPager{

Pager（conststring&

Pager（constPager&

p）:

str（p.str）{}

Pager&

operator=（constPager&

p）{

p）

str=p.str;

classBusinessTraveler:

publicTraveler{

Pagerpager;

BusinessTraveler（）:

Traveler（"

"

）,pager（"

）{}

BusinessTraveler（conststring&

t,conststring&

p）

:

Traveler（t）,pager（p）{}

BusinessTraveler（constBusinessTraveler&

b）

Traveler（b）,pager（b.pager）{}

BusinessTraveler&

operator=（constBusinessTraveler&

b）{

b）{

Traveler:

operator=（b）;

//Assignbasepart

pager=b.pager;

//Assignderivedpart

friendostream&

operator<

（ostream&

os,

constBusinessTraveler&

returnos<

{\"

<

b.getString（）<

\"

\"

b.pager.getString（）<

}"

BusinessTravelerb1（"

JoeBusinessMan"

"

Pager1"

b1<

BusinessTravelerb2（"

JaneBusinessWoman"

Pager2"

b2<

BusinessTravelerb3;

b3<

BusinessTravelerb4（b1）;

b4<

b3=b2;

{"

}*/

ThesolutionisalittleclearerifBusinessTravelerhasaconstructorthattakestwoarguments:

onefortheTraveler’snameandoneforthePagername.Thekeypointofthisexerciseistogettheconstructorandassignmentoperatorcorrectwithinheritance.Bothneedtomakesurethatthebaseclasssub-objectistakencareof（whichissometimeseasytoforget!

）.Inconstructorsyouusetheinitializerlist;

inassignmentoperatorsyouexplicitlycallthebaseclassassignmentoperator（sincethebaseclassdataisprivate,youhavenochoice）.

14-15

Createaclasswithtwostaticmemberfunctions.Inheritfromthisclassandredefineoneofthememberfunctions.Showthattheotherishiddeninthederivedclass.

StaticBaseMethods.cpp

classBase{

staticvoidf（）{

Base:

f（）\n"

staticvoidg（）{

g（）\n"

classDerived:

publicBase{

staticvoidg（int）{

Derived:

g（int）\n"

Derived:

f（）;

g

（1）;

//Derived:

g（）;

//Error:

toofewparameters

f（）

g（int）

ThefactthatIintroducedaparameterforg（）inDerivedisnotsignificant;

anyfunctionnamedthesameasoneinanybaseclasshidesalloverloadedfunctionsofthesamenameinthebaseclasses（becausederivedclassesconstituteanestedscope）.

14-16

Lookupmoreofthememberfunctionsfori