面向对象的C++程序设计 第六版 课后习题答案第四章.docx
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面向对象的C++程序设计第六版课后习题答案第四章
Chapter4
ProceduralAbstractionandFunctionsThatReturnaValue
1.SolutionstoandRemarksonSelectedProgrammingProblems
1.Nosolutionprovided.
2.Nosolutionprovided.
3.ValueofStockHoldings
Thisprogramasksforinputofthepriceofastock,thenumberofstocksowned,andoutputsthevalueofthestockholdingindollarsandcents.Theprogramshoulddefineafunctionthatacceptsthepriceofthestockinthreeintvalues:
wholedollars,numeratoroffraction,anddenominatorofthefraction,thenoutputsthevalueofthestockasadouble.Forexample,forastockwhosepricewas77/8dollars,theinputwouldbe77/8andtheoutputwouldbe7.87（usinga"5'sroundodd"rule.）Insupervisedstudentlabs,Ifindtheerrorofhavingafunctionprototypedifferentinsomeessentialwaythanthefunctiondefinitiontobeaprevalenterror.
TheAlgorithminPseudocodeandincode:
//requiredfunction:
//returnvalue=dollars+num/denomwithappropriatecasts
//doubleconvert（intdollars,intnum,intdenom）
//getpricewithfraction,numberofshares
//callfunctiontoconvertpricewithfractiontopriceasdouble
//value=price*（numberofshares）
//outputvalue
//Program:
//fileCh3Prob2.cc
//problem:
takeinputofnumberofshares,priceasdollars,
//numeratoranddenominatoroffractionalpartofprice,give
//valueofholdings.
doubleconvert（intdollars,intnum,intden）;
//acceptasinputthestockpricewithfraction,return
//priceasdouble
#include
usingnamespacestd;
intmain（）
{
intdollars,numer,denom,shares;
doubleprice,value;
cout<<"Enterstockpriceandnumberofshares,please.\n"
<<"Enterpriceasintegers:
dollars,numerator,“
<<“denominator."<cin>>dollars>>numer>>denom;
cout<<"Enternumberofsharesheld."<cin>>shares;
price=convert（dollars,numer,denom）;
value=price*shares;
cout.setf（ios:
:
fixed）;
cout.setf（ios:
:
showpoint）;
cout.precision
（2）;
cout<<<<"havevalue$"<return0;
}
doubleconvert（intdollars,intnum,intden）
{
returndollars+double（num）/den;
}
Atypicalrunfollows.
14:
24:
24:
~/AW$a.out
Enterstockpriceandnumberofshares,please.
Enterpriceasintegers:
dollars,numerator,denominator.
1058
Enternumberofsharesheld.
100
100sharesofstockwithmarketprice105/8
havevalue$1062.50
14:
24:
32:
~/AW$
4.Nosolutionprovided.
5.Nosolutionprovided.
6.CreditCardInterest
Thisprogramcomputesinterestonacreditcardbalance.Thetaskisdonewithafunctionthatacceptsinitialbalance,monthlyinterestrate,numberofmonthsforwhichtheinterestmustbepaid.Thevaluereturnedistheinterestdue.Allowrepeatatuser'soption.NBInterestiscompounded.Functionistobeembedinaprogramthatacquiresthesevaluesandoutputstheinterestdue.Repeatofcomputationatusersoptionistobeallowed.
Algorithminpseudocode:
Functionname:
interest
input:
fetchvaluesfor:
doubleinitBalance,doublerate,intmonths.
process:
declarebalance=initBalance,interest;
declareindex=0;
while（index{
balance=balance*（1+rate）;
months++;
}
interest=balance-initBalance;
output:
interest
main:
declarebalancerate,interestEarned,months
fetchbalance,rate,months
interestEarned=interest（balance,rate,months）
outputinterestEarned
Code:
//file:
ch4Prog5.cc
#include
usingnamespacestd;
//Problem:
//giveninitialbalance,rateandmonthsto
//run,howmuchinterestaccruesonacreditcard?
//allowrepetitionatuser'soption.
//computecompoundcreditcardinterest
doubleinterest（doubleinitBalance,
doublerate,intmonths）
{
doublebalance=initBalance;
inti=0;
while（i{
balance=balance*（1+rate）;
i++;
}
returnbalance-initBalance;
}
intmain（）
{
doublebalance,rate,interestEarned;
intmonths;
charans;
cout.setf（ios:
:
showpoint）;
cout.setf（ios:
:
fixed）;
cout.precision
（2）;
do
{
cout<<"Creditcardinterest"<<<"Enterdoubles:
initialbalance,“
<<“monthlyinterestrateas\n"
<<"adecimalfraction,e.g.for1.5%“
<<”permonthwrite0.015\n"
<<"andintmonthsthebillhasrun.\n"
<<"Iwillgiveyoutheinterestthat“
<<”hasaccumulated.\n";
cin>>balance>>rate>>months;
interestEarned=interest（balance,rate,
months）;
cout<<"Interestaccumulated=$"
<cout<<"Yoryrepeats,anyothercharacter”
<<“quits"<cin>>ans;
}while（'Y'==ans||'y'==ans）;
return0;
}
Atypicalrunfollows:
15:
19:
13:
~/AW$a.out
Creditcardinterest
Enterdoubles:
initialbalance,monthlyinterestrateas
adecimalfraction,e.g.for1.5%permonthwrite0.015
andintmonthsthebillhasrun.
Iwillgiveyoutheinterestthathasaccumulated.
1000
.015
12
Interestaccumulated=$195.62
Yoryrepeats,anyothercharacterquits
y
Creditcardinterest
Enterdoubles:
initialbalance,monthlyinterestrateas
adecimalfraction,e.g.for1.5%permonthwrite0.015
andintmonthsthebillhasrun.
Iwillgiveyoutheinterestthathasaccumulated.
1000
.021
12
Interestaccumulated=$283.24
Yoryrepeats,anyothercharacterquits
q
15:
19:
35:
~/AW$
7.Nosolutionprovided
8.Nosolutionprovided
9.Clothessizecalculation
Themajorproblemforstudentsinthisasinmany‘wordproblems’isdeterminingtheformulasfromtheproblemstatement.
Givenheight,weight,age,computeclothessizes:
hatSize=weight（lbs.）/height（in.）*2.9
jacketSize（chestsize,in.）=
height*weight/288+（1/8）*（age-30）/10
Notecarefullythattheadjustmentonlyoccursforcomplete10yearintervalafterage30,i.e.,ifage<40,thereisnoadjustment!
40<=age<49gets1/8in.adjustment,etc.
waist（in.）=weight/5.7+（1/10）*（age-28）/2
NB:
adjustmentonlyoccursforcomplete2year
intervalafter28
age=29,noadjustment
30<=age<32,1/10inchadjustment.
Useafunctionforeachcalculation.
Allowrepetitionatuseroption.
Nowlet'smakesomedeclarations:
intheight;//inches
intweight;//lbs
intage;//years
doublejacketSize;//inchesatchest
doublewaist;//inchesatwaist
doublehatSize;
HatSizeCalculation:
hatsize=2.9*double（weight）/height;
Thecastisclearer,butisnotstrictlynecessary.Theweightwouldbepromotedautomaticallywhenmultiplicationby2.9occurs.（Thisiswhythe2.9isfirst!
）
JacketSizeCalculation:
jacket=double（height）*weight/288
if（age>40）
jacket=jacket+（age-30）/10*0.125;
ThisdependsonthebehavioroftheC/C++languagetoobtaintheresultsrequired.The（age-30/10）arithmeticwillbedoneasint,sincethereisnothingtorequiretypechange.Theintresultwillbethenconvertedtodoubleinthemultiplicationbythe0.125（whichis1/8asadecimal.）
WaistSizeCalculation:
size=weight/5.7;
if（age>=30）
size=size+（age-28）/2*0.1;
Again,theweightwillbeconvertedtodoubleinthedivisionby5.7.Theexpression,（age-28）/2,willbecomputedasanint,thenbepromotedtodoubleinthemultiplicationby0.1.
//file:
ch4Prb8.cc
//problem:
Clothessizecalculation:
//givenheight（inches）weight（pounds）andage（years）
//computejacketsize,waistsize,ininches,andhatsize:
//returnshatsizeinstandardhatsizeunits
#include
usingnamespacestd;
doublehatSize（intheight,intweight）
{
return2.9*double（weight）/height;
}
//returnsjacketSizeininchesatthechest
doublejacketSize（intheight,intweight,intage）
{
doublejacket=double（height）*weight/288;
if（age>40）
jacket=jacket+（age-30）/10*0.125;
returnjacket;
}
//returnswaistsizeininches
doublewaistSize（intheight,intweight,intage）
{
doublesize=weight/5.7;
if（age>=30）
size=size+（age-28）/2*0.1;
returnsize;
}
intmain（）
{
intheight,weight,age;
doublehat,jacket,waist;
charans;
do
{
cout<<"Givemeyourheightininches,weightin"
<<"pounds,andageinyears"<<<"andIwillgiveyouyourhatsize,jacket"
<<"size（inchesatchest）"<<<"andyourwaistsizeininches."<cin>>height>>weight>>age;
hat=hatSize（height,weight）;
jacket=jacketSize（height,weight,age）;
waist=waistSize（height,weight,age）;
cout.setf（ios:
:
showpoint）;
cout.setf（ios:
:
fixed）;
cout.precision
（2）;
cout<<"hatsize="<cout<<"jacketsize="<cout<<"waistsize="<cout<<<"enterYorytorepeat,“
<<“anyothercharacterends."<cin>>ans;
}while（'Y'==ans||'y'==ans）;
return0;
}
Atypicalrunfollows:
17:
07:
37:
~/AW$a.out
Givemeyourheightininches,weightinpounds,andageinyears
andIwillgiveyouyourhatsize,jacketsize（inchesatchest）
andyourwaistsizeininches.
6918550
hatsize=7.78
jacketsize=44.57
waistsize=33.56
enterYorytorepeat,anyothercharacterends.
y
Givemeyourheightininches,weightinpounds,andageinyears
andIwillgiveyouyourhatsize,jacketsize（inchesatchest）
andyourwaistsizeininches.
6720058
hatsize=8.66
jacketsize=46.78
waistsize=36.59
enterYorytorepeat,anyothercharacterends.
n
17:
08:
55:
~/AW$
Nosolutionsprovidedforproblems10-12.
13.
//***********************************************************************
//Ch4Proj13.cpp
//
//Thisprogramoutputsthe99bottlesofbeeronthewallsong.
//Asimpleloopcallsafunctionthatoutputseachstanza
//foraparticu
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