精選精選Chapter2AnswerstoSelectedExercises[was#2](a)Theprogramcontainsonedirective(#include)andfourstatements(threecallsofprintfandonereturn).(b)Parkinson'sLaw:Workexpandssoastofillthetimeavailableforitscompletion.[was#4]#include<stdio.h>intmain(void){intheight=8,length=12,width=10,volume;volume=height*length*width;printf("Dimensions:%dx%dx%d\n",length,width,height);printf("Volume(cubicinches):%d\n",volume);printf("Dimensionalweight(pounds):%d\n",(volume+165)/166);return0;[was#6]Here'sonepossibleprogram:#include<stdio.h>intmain(void){inti,j,k;floatx,y,z;printf("Valueofi:%d\n",i);printf("Valueofj:%d\n",j);printf("Valueofk:%d\n",k);printf("Valueofx:%g\n",x);printf("Valueofy:%g\n",y);printf("Valueofz:%g\n",z);return0;}WhencompiledusingGCCandthenexecuted,thisprogramproducedthefollowingoutput:Valueofi:5618848Valueofj:0Valueofk:6844404Valueofx:3.98979e-34Valueofy:9.59105e-39Valueofz:9.59105e-39Thevaluesprinteddependonmanyfactors,sothechancethatyou'llgetexactlythesenumbersissmall.[was#10](a)isnotlegalbecause100_bottlesbeginswithadigit.8.[was#12]Thereare14tokens:a,=,(,3,*,q,-,p,*,p,),/,3,and;.AnswerstoSelectedProgrammingProjects4.[was#8;modified]#include<stdio.h>intmain(void){floatoriginal_amount,amount_with_tax;printf("Enteranamount:");scanf("%f",&original_amount);amount_with_tax=original_amount*1.05f;printf("Withtaxadded:$%.2f\n",amount_with_tax);return0;}Theamount_with_taxvariableisunnecessary.Ifweremoveit,theprogramisslightlyshorter:#include<stdio.h>intmain(void)floatoriginal_amount;printf("Enteranamount:");scanf("%f",&original_amount);printf("Withtaxadded:$%.2f\n",original_amount*1.05f);return0;Chapter3AnswerstoSelectedExercises[was#2]printf("%-8.1e",x);printf("%10.6e",x);printf("%-8.3f",x);printf("%6.0f",x);5.[was#8]Thevaluesofx,i,andywillbe12.3,45,and.6,respectively.AnswerstoSelectedProgrammingProjects1.[was#4;modified]#include<stdio.h>intmain(void){intmonth,day,year;printf("Enteradate(mm/dd/yyyy):");scanf("%d/%d/%d",&month,&day,&year);printf("Youenteredthedate%d%.2d%.2d\n",year,month,day);return0;}[was#6;modified]#include<stdio.h>intmain(void){intprefix,group,publisher,item,check_digit;printf("EnterISBN:");scanf("%d-%d-%d-%d-%d",&prefix,&group,&publisher,&item,&check_digit);printf("GS1prefix:%d\n",prefix);printf("Groupidentifier:%d\n",group);printf("Publishercode:%d\n",publisher);printf("Itemnumber:%d\n",item);printf("Checkdigit:%d\n",check_digit);/*Thefiveprintfcallscanbecombinedasfollows:printf("GS1prefix:%d\nGroupidentifier:%d\nPublishercode:%d\nItemnumber:%d\nCheckdigit:%d\n",prefix,group,publisher,item,check_digit);*/return0;}Chapter4AnswerstoSelectedExercises[was#2]NotinC89.Supposethatiis9andjis7.Thevalueof(-i)/jcouldbeeither-1or-2,dependingontheimplementation.Ontheotherhand,thevalueof-(i/j)isalways-1,regardlessoftheimplementation.InC99,ontheotherhand,thevalueof(-i)/jmustbeequaltothevalueof-(i/j).[was#6]6383212-1300013.[was#8]Theexpression++iisequivalentto(i+=1).Thevalueofbothexpressionsisiaftertheincrementhasbeenperformed.AnswerstoSelectedProgrammingProjects2.[was#4]#include<stdio.h>intmain(void){intn;printf("Enterathree-digitnumber:");scanf("%d",&n);printf("Thereversalis:%d%d%d\n",n%10,(n/10)%10,n/100);return0;}Chapter5AnswerstoSelectedExercises2.[was#2]11114.[was#4](i>j)-(i<j)6.[was#12]Yes,thestatementislegal.Whennisequalto5,itdoesnothing,since5isnotequalto-9.10.[was#16]Theoutputisonetwosincetherearenobreakstatementsafterthecases.AnswerstoSelectedProgrammingProjects2.[was#6]#include<stdio.h>intmain(void){inthours,minutes;printf("Entera24-hourtime:");scanf("%d:%d",&hours,&minutes);printf("Equivalent12-hourtime:");if(hours==0)printf("12:%.2dAM\n",minutes);elseif(hours<12)printf("%d:%.2dAM\n",hours,minutes);elseif(hours==12)printf("%d:%.2dPM\n",hours,minutes);elseprintf("%d:%.2dPM\n",hours-12,minutes);return0;4.[was#8;modified]#include<stdio.h>intmain(void){intspeed;printf("Enterawindspeedinknots:");scanf("%d",&speed);if(speed<1)printf("Calm\n");elseif(speed<=3)printf("Lightair\n");elseif(speed<=27)printf("Breeze\n");elseif(speed<=47)printf("Gale\n");elseif(speed<=63)printf("Storm\n");elseprintf("Hurricane\n");return0;6.[was#10]#include<stdio.h>intmain(void)intcheck_digit,d,i1,i2,i3,i4,i5,j1,j2,j3,j4,j5,first_sum,second_sum,total;printf("Enterthefirst(single)digit:");scanf("%1d",&d);printf("Enterfirstgroupoffivedigits:");scanf("%1d%1d%1d%1d%1d",&i1,&i2,&i3,&i4,&i5);printf("Entersecondgroupoffivedigits:");scanf("%1d%1d%1d%1d%1d",&j1,&j2,&j3,&j4,&j5);printf("Enterthelast(single)digit:");scanf("%1d",&check_digit);first_sum=d+i2+i4+j1+j3+j5;second_sum=i1+i3+i5+j2+j4;total=3*first_sum+second_sum;if(check_digit==9-((total-1)%10))printf("VALID\n");elseprintf("NOTVALID\n");return0;}10.[was#14]#include<stdio.h>intmain(void){intgrade;printf("Enternumericalgrade:");scanf("%d",&grade);if(grade<0||grade>100){printf("Illegalgrade\n");return0;}switch(grade/10){case10:case9:printf("Lettergrade:A\n");break;case8:printf("Lettergrade:B\n");break;case7:printf("Lettergrade:C\n");break;case6:printf("Lettergrade:D\n");break;case5:case4:case3:case2:case1:case0:printf("Lettergrade:F\n");break;}return0;}Chapter6AnswerstoSelectedExercises4.[was#10](c)isnotequivalentto(a)and(b),becauseiisincremenbteefdoretheloopbodyisexecuted.10.[was#12]Considerthefollowingwhileloop:while(…){…continue;…}Theequivalentcodeusinggotowouldhavethefollowingappearance:while(…){…gotoloop_end;…loop_end:;/*nullstatement*/}12.[was#14]for(d=2;d*d<=n;d++)if(n%d==0)break;Theifstatementthatfollowstheloopwillneedtobemodifiedaswell:if(d*d<=n)printf("%disdivisibleby%d\n",n,d);elseprintf("%disprime\n",n);14.[was#16]Theproblemisthesemicolonattheendofthefirstline.Ifweremoveit,thestatementisnowcorrect:if(n%2==0)printf("niseven\n");AnswerstoSelectedProgrammingProjects2.[was#2]#include<stdio.h>intmain(void){intm,n,remainder;printf("Entertwointegers:");scanf("%d%d",&m,&n);while(n!=0){remainder=m%n;m=n;n=remainder;}printf("Greatestcommondivisor:%d\n",m);return0;}4.[was#4]#include<stdio.h>intmain(void){floatcommission,value;printf("Entervalueoftrade:");scanf("%f",&value);while(value!=0.0f){if(value<2500.00f)commission=30.00f+.017f*value;elseif(value<6250.00f)commission=56.00f+.0066f*value;elseif(value<20000.00f)commission=76.00f+.0034f*value;elseif(value<50000.00f)commission=100.00f+.0022f*value;elseif(value<500000.00f)commission=155.00f+.0011f*value;elsecommission=255.00f+.0009f*value;if(commission<39.00f)commission=39.00f;printf("Commission:$%.2f\n\n",commission);printf("Entervalueoftrade:");scanf("%f",&value);}return0;}6.[was#6]#include<stdio.h>intmain(void){inti,n;printf("Enterlimitonmaximumsquare:");scanf("%d",&n);for(i=2;i*i<=n;i+=2)printf("%d\n",i*i);return0;}8.[was#8]#include<stdio.h>intmain(void){inti,n,start_day;printf("Enternumberofdaysinmonth:");scanf("%d",&n);printf("Enterstartingdayoftheweek(1=Sun,7=Sat):");scanf("%d",&start_day);/*printanyleading"blankdates"*/for(i=1;i<start_day;i++)printf("");/*nowprintthecalendar*/for(i=1;i<=n;i++){printf("%3d",i);if((start_day+i-1)%7==0)printf("\n");}return0;}Chapter7AnswerstoSelectedExercises[was#4](b)isnotlegal.[was#6](d)isillegal,sinceprintfrequiresastring,notacharacter,asitsfirstargument.10.[was#14]unsignedint,becausethe(int)castappliesonlytoj,notj*k.12.[was#16]Thevalueofiisconvertedtofloatandaddedtof,thentheresultisconvertedtodoubleandstoredind.14.[was#18]No.Convertingftointwillfailifthevaluestoredinfexceedsthelargestvalueoftypeint.AnswerstoSelectedProgrammingProjects[was#2]shortintvaluesareusuallystoredin16bits,andlongintvaluesareusuallystoredin32bits,withfailureoccurringat46341.[was#8]#include<stdio.h>intmain(void){inti,n;charch;printf("Thisprogramprintsatableofsquares.\n");printf("Enternumberofentriesintable:");scanf("%d",&n);ch=getchar();/*disposeofnew-linecharacterfollowingnumberofentries*//*couldsimplybegetchar();*/for(i=1;i<=n;i++){printf("%10d%10d\n",i,i*i);if(i%24==0){printf("PressEntertocontinue...");ch=getchar();/*orsimplygetchar();*/}}return0;}[was#10]#include<ctype.h>#include<stdio.h>intmain(void){intsum=0;charch;printf("Enteraword:");while((ch=getchar())!='\n')switch(toupper(ch)){case'D':case'G':sum+=2;break;case'B':case'C':case'M':case'P':sum+=3;break;case'F':case'H':case'V':case'W':case'Y':sum+=4;break;case'K':sum+=5;break;case'J':case'X':sum+=8;break;case'Q':case'Z':sum+=10;break;default:sum++;break;}printf("Scrabblevalue:%d\n",sum);return0;}[was#12]#include<stdio.h>intmain(void){printf("Sizeofint:%d\n",(int)sizeof(int));printf("Sizeofshort:%d\n",(int)sizeof(short));printf("Sizeoflong:%d\n",(int)sizeof(long));printf("Sizeoffloat:%d\n",(int)sizeof(float));printf("Sizeofdouble:%d\n",(int)sizeof(double));printf("Sizeoflongdouble:%d\n",(int)sizeof(longdouble));return0;}Sincethetypeofasizeofexpressionmayvaryfromoneimplementationtoanother,it'snecessaryinC89tocastsizeofexpressionstoaknowntypebeforeprintingthem.Thesizesofthebasictypesaresmallnumbers,soit'ssafetocastthemtoint.(Ingeneral,however,it'sbesttocastsizeofexpressionstounsignedlongandprintthemusing%lu.)InC99,wecanavoidthecastbyusingthe%zuconversionspecification.Chapter8AnswerstoSelectedExercises[was#4]Theproblemwithsizeof(a)/sizeoft()isthatitcan'teasilybecheckedforcorrectnessbysomeonereadingtheprogram.(Thereaderwouldhavetolocatethedeclarationofaandmakesurethatitselementshavetty.)pe[was#8]Touseadigitd(incharacterform)asasubscriptintothearraya,wewouldwritea[d-'0'].Thisassumesthatdigitshaveconsecutivecodesintheunderlyingcharacterset,whichistrueofASCIIandotherpopularcharactersets.[was#10]constintsegments[10][7]={{1,1,1,1,1,1},{0,1,1},{1,1,0,1,1,0,1},{1,1,1,1,0,0,1},{0,1,1,0,0,1,1},{1,0,1,1,0,1,1},{1,0,1,1,1,1,1},{1,1,1},{1,1,1,1,1,1,1},{1,1,1,1,0,1,1}};AnswerstoSelectedProgrammingProjects2.[was#2]#include<stdio.h>intmain(void){intdigit_count[10]={0};intdigit;longn;printf("Enteranumber:");scanf("%ld",&n);while(n>0){digit=n%10;digit_count[digit]++;n/=10;}printf("Digit: ");for(digit=0;digit<=9;digit++)printf("%3d",digit);printf("\nOccurrences:");for(digit=0;digit<=9;digit++)printf("%3d",digit_count[digit]);printf("\n");return0;[was#6]#include<stdio.h>#defineNUM_RATES((int)(sizeof(value)/sizeof(value[0])))#defineINITIAL_BALANCE100.00intmain(void){inti,low_rate,month,num_years,year;doublevalue[5];printf("Enterinterestrate:");scanf("%d",&low_rate);printf("Enternumberofyears:");scanf("%d",&num_years);printf("\nYears");for(i=0;i<NUM_RATES;i++){printf("%6d%%",low_rate+i);value[i]=INITIAL_BALANCE;printf("\n");for(year=1;year<=num_years;year++){printf("%3d",year);for(i=0;i<NUM_RATES;i++){for(month=1;month<=12;month++)value[i]+=((double)(low_rate+i)/12)/100.0*value[i];printf("%7.2f",value[i]);}printf("\n");}return0;}[was#12]#include<stdio.h>#defineNUM_QUIZZES5#defineNUM_STUDENTS5intmain(void){intgrades[NUM_STUDENTS][NUM_QUIZZES];inthigh,low,quiz,student,total;for(student=0;student<NUM_STUDENTS;student++){printf("Entergradesforstudent%d:",student+1);for(quiz=0;quiz<NUM_QUIZZES;quiz++)scanf("%d",&grades[student][quiz]);}printf("\nStudentTotalAverage\n");for(student=0;student<NUM_STUDENTS;student++){printf("%4d",student+1);total=0;for(quiz=0;quiz<NUM_QUIZZES;quiz++)total+=grades[student][quiz];printf("%3d%3d\n",total,total/NUM_QUIZZES);}printf("\nQuizAverageHighLow\n");for(quiz=0;quiz<NUM_QUIZZES;quiz++){printf("%3d",quiz+1);total=0;high=0;low=100;for(student=0;student<NUM_STUDENTS;student++){total+=grades[student][quiz];if(grades[student][quiz]>high)high=grades[student][quiz];if(grades[student][quiz]<low)low=grades[student][quiz];}printf("%3d%3d %3d\n",total/NUM_STUDENTS,high,low);}return0;}Chapter9AnswerstoSelectedExercises2.[was#2]intcheck(intx,inty,intn){return(x>=0&&x<=n-1&&y>=0&&y<=n-1);}4.[was#4]intday_of_year(intmonth,intday,intyear)intnum_days[]={31,28,31,30,31,30,31,31,30,31,30,31};intday_count=0,i;for(i=1;i<month;i++)day_count+=num_days[i-1];/*adjustforleapyears,assumingtheyaredivisibleby4*/if(year%4==0&&month>2)day_count++;returnday_count+day;Usingtheexpressionyear%4==0totestforleapyearsisnotcompletelycorrect.Centuriesarespecialcases:ifayearisamultipleof100,thenitmustalsobeamultipleof400inordertobealeapyear.Thecorrecttestisyear%4==0&&(year%100!=0||year%400==0)6.[was#6;modified]intdigit(intn,intk)inti;for(i=1;i<k;i++)n/=10;returnn%10;}8.[was#8](a)and(b)arevalidprototypes.(c)isillegal,sinceitdoesn'tspecifythetypeoftheparameter.(d)incorrectlyspecifiesthatfreturnsanintvalueinC89;inC99,omittingthereturntypeisillegal.[was#10]intlargest(inta[],intn){inti,max=a[0];for(i=1;i<n;i++)if(a[i]>max)max=a[i];returnmax;}intaverage(inta[],intn){inti,avg=0;for(i=0;i<n;i++)avg+=a[i];returnavg/n;}intnum_positive(inta[],intn){inti,count=0;for(i=0;i<n;i++)if(a[i]>0)count++;returncount;}15.[was#12;modified]doublemedian(doublex,doubley,doublez)doubleresult;if(x<=y)if(y<=z)result=y;elseif(x<=z)result=z;elseresult=x;else{if(z<=y)result=y;elseif(x<=z)result=x;elseresult=z;}returnresult;}17.[was#14]intfact(intn){inti,result=1;for(i=2;i<=n;i++)result*=i;returnresult;19.[was#16]Thefollowingprogramteststhepbfunction:#include<stdio.h>voidpb(intn);intmain(void){intn;printf("Enteranumber:");scanf("%d",&n);printf("Outputofpb:");pb(n);printf("\n");return0;}voidpb(intn){if(n!=0){pb(n/2);putchar('0'+n%2);}}pbprintsthebinaryrepresentationoftheargumentn,assumingthatnisgreaterthan0.(Wealsoassumethatdigitshaveconsecutivecodesintheunderlyingcharacterset.)Forexample:Enteranumber:53Outputofpb:110101Atraceofpb'sexecutionwouldlooklikethis:pb(53)findsthat53isnotequalto0,soitcallspb(26),whichfindsthat26isnotequalto0,soitcallspb(13),whichfindsthat13isnotequalto0,soitcallspb(6),whichfindsthat6isnotequalto0,soitcallspb(3),whichfindsthat3isnotequalto0,soitcallspb(1),whichfindsthat1isnotequalto0,soitcallspb(0),whichfindsthat0isequalto0,soitreturns,causingpb(1)toprint1andreturn,causingpb(3)toprint1andreturn,causingpb(6)toprint0andreturn,causingpb(13)toprint1andreturn,causingpb(26)toprint0andreturn,causingpb(53)toprint1andreturn.Chapter10AnswerstoSelectedExercises1.[was#2](a)a,b,andcarevisible.a,anddarevisible.a,d,andearevisible.aandfarevisible.AnswerstoSelectedProgrammingProjects3.[was#4]include<stdbool.h>/*C99only*/#include<stdio.h>#include<stdlib.h>defineNUM_CARDS5defineRANK0defineSUIT1

/*externalvariables*/inthand[NUM_CARDS][2];TOC\o"1-5"\h\z/* 0 10| | || | || | || | || | |ranksuit*/boolstraight,flush,four,three;intpairs;/*canbe0,1,or2*//*prototypes*/voidread_cards(void);voidanalyze_hand(void);voidprint_result(void);/***********************************************************main:Callsread_cards,analyze_hand,andprint_result*repeatedly.*/**********************************************************/intmain(void){for(;;){read_cards();analyze_hand();print_result();}}/***********************************************************read_cards:Readsthecardsintotheexternalvariable*hand;checksforbadcardsandduplicate*cards.*********************************************************voidread_cards(void){charch,rank_ch,suit_ch;inti,rank,suit;boolbad_card,duplicate_card;intcards_read=0;while(cards_read<NUM_CARDS){bad_card=false;printf("Enteracard:");rank_ch=getchar();switch(rank_ch){case'0':exit(EXIT_SUCCESS);case'2':rank=0;break;case'3':rank=1;break;case'4':rank=2;break;case'5':rank=3;break;case'6':rank=4;break;case'7':rank5;break;case'8':rank=6;break;case'9':rank=7;break;case't':case'T':rank=8;break;case'j':case'J':rank=9;break;case'q':case'Q':rank=10;break;case'k':case'K':rank=11;break;case'a':case'A':rank=12;break;default: bad_card=true;}suit_ch=getchar();switch(suit_ch){case'c':case'C':suit=0;break;case'd':case'D':suit=1;break;case'h':case'H':suit=2;break;case's':case'S':suit=3;break;default: bad_card=true;}while((ch=getchar())!='\n')if(ch!='')bad_card=true;if(bad_card){printf("Badcard;ignored.\n");continue;}duplicate_card=false;for(i=0;i<cards_read;i++)if(hand[i][RANK]==rank&&hand[i][SUIT]==suit){printf("Duplicatecard;ignored.\n");duplicate_card=true;break;}if(!duplicate_card){hand[cards_read][RANK]=rank;hand[cards_read][SUIT]=suit;cards_read++;}}}/***********************************************************analyze_hand:Determineswhetherthehandcontainsa*straight,aflush,four-of-a-kind,and/orthree-of-a-kind;determinesthe*numberofpairs;storestheresultsinto*theexternalvariablesstraight,flush,*four,three,andpairs.**********************************************************/voidanalyze_hand(void)intrank,suit,card,pass,run;straight=true;flush=true;four=false;three=false;pairs=0;/*sortcardsbyrank*/for(pass=1;pass<NUM_CARDS;pass++)for(card=0;card<NUM_CARDS-pass;card++){rank=hand[card][RANK];suit=hand[card][SUIT];if(hand[card+1][RANK]<rank){hand[card][RANK]=hand[card+1][RANK];hand[card][SUIT]=hand[card+1][SUIT];hand[card+1][RANK]=rank;hand[card+1][SUIT]=suit;}}/*checkforflush*/suit=hand[0][SUIT];for(card=1;card<NUM_CARDS;card++)if(hand[card][SUIT]!=suit)flush=false;/*checkforstraight*/for(card=0;card<NUM_CARDS-1;card++)if(hand[card][RANK]+1!=hand[card+1][RANK])straightstraight=false;精選精選/*checkfor4-of-a-kind,3-of-a-kind,andpairsbylookingfor"runs"ofcardswithidenticalranks*/card=0;while(card<NUM_CARDS){rank=hand[card][RANK];run=0;do{run++;card++;}while(card<NUM_CARDS&&hand[card][RANK]==rank);switch(run){pairs++;break;three=true;break;four=true;break;}}}/**********************************************************print_result:Printstheclassificationofthehand,*basedonthevaluesoftheexternal*精選精選variablesstraight,flush,four,three,*andpairs.*/**********************************************************/voidprint_result(void){if(straight&&flush)printf("Straightflush");elseif(four) printf("Fourofakind");elseif(three&&printf("Fullhouse");printf("Flush");printf("Straight");printf("Fullhouse");printf("Flush");printf("Straight");printf("Threeofakind")printf("Twopairs");printf("Pair");printf("Highcard");elseif(flush)elseif(straight)elseif(three)elseif(pairs==2)elseif(pairs==1)elseprintf("\n\n");}.[was#6]#include<stdbool.h>/*C99only*/#include<stdio.h>#include<stdlib.h>#defineNUM_RANKS13#defineNUM_SUITS4#defineNUM_CARDS5/*externalvariables*/intnum_in_rank[NUM_RANKS];intnum_in_suit[NUM_SUITS];boolstraight,flush,four,three;intpairs;/*canbe0,1,or2*//*prototypes*/voidread_cards(void);voidanalyze_hand(void);voidprint_result(void);/***********************************************************main:Callsread_cards,analyze_hand,andprint_result**repeatedly.**********************************************************/intmain(void)for(;;){read_cards();

analyze_hand();print_result();}}/***********************************************************readcards:Readsthecardsintotheexternalvariablesnum_in_rankandnum_in_suit;*checksforbadcardsandduplicatecards*.*/*******************************