《C Primer Plus》第六 第十二章编程练习答案.docx

C Primer Plus第六 第十二章编程练习答案1. #include<stdio.h> int critic(void ); int main(intargc, char *argv) intnum=56; int units; printf("How many pounds to a firkin of butter?n"); scanf("%d",&units); while (units!=num) units=critic; getchar; return 0; int critic int n; printf("No luck, my friend. Try again.n"); scanf("%d", &n); return n; 2. /*pe12-2a.h*/ #include<stdio.h> voidset_mode(int mode); voidget_info; voidshow_info; /*pe12-2a.c*/ #include<stdio.h> #include"pe12-2a.h" int mode; float distance, fuel; voidset_mode(intm) if (m !=0 &&m !=1) printf("Invalid mode specified. Mode 1(US) used.n"); m=1; mode=m; voidget_info if (0=mode) printf("Enter distance traveled in kilometers: "); scanf("%f", &distance); printf("Enter fuel consumed in liters: "); scanf("%f", &fuel); else printf("Enter distance traveled in miles: "); scanf("%f", &distance); printf("Enter fuel consumed in gallons: "); scanf("%f", &fuel); voidshow_info float units; if (0=mode) units=100* (fuel/distance); printf("Fuel consumed in liters: %.1f per 100 kmn", units); else units=distance/fuel; printf("Fuel consumed is %.1f miles per gallonn", units); 3. /*pe12-2a.h*/ #include<stdio.h> voidset_mode(int mode); voidget_info(int mode); voidshow_info(int mode, float distance, float fuel); /*pe12-2a.c*/ #include<stdio.h> #include"pe12-2a.h" voidset_mode(intmode) if (mode !=0 &&mode !=1) printf("Invalid mode specified. Mode 1(US) used.n"); mode=1; get_info(mode); voidget_info(intmode) float distance, fuel; if (0=mode) printf("Enter distance traveled in kilometers: "); scanf("%f", &distance); printf("Enter fuel consumed in liters: "); scanf("%f", &fuel); else printf("Enter distance traveled in miles: "); scanf("%f", &distance); printf("Enter fuel consumed in gallons: "); scanf("%f", &fuel); show_info(mode, distance, fuel); voidshow_info(intmode, floatdistance, floatfuel) float units; if (0=mode) units=100* (fuel/distance); printf("Fuel consumed in liters: %.1f per 100 kmn", units); else units=distance/fuel; printf("Fuel consumed is %.1f miles per gallonn", units); /*pe12-2b.c*/ #include<stdio.h> #include"pe12-2a.h" int main(void) int mode; printf("Enter 0 for metric mode, 1 for US mode: "); scanf("%d", &mode); while(mode>=0) set_mode(mode); printf("Enter 0 for metric mode, 1 for US mode: "); printf("(-1 to quit): "); scanf("%d", &mode); printf("Done,n"); getchar; return 0; 4. #include<stdio.h> int count=0; int fun; int main(void) inti=0; intcnt; while (i<20) cnt=fun; printf("The function has been called %d times:n", cnt); i+; getchar; return 0; int fun count+; return count; 5. /*main.c*/ #include<stdio.h> #include"rand0.h" int main(void) intStr100; int count; for(count=0; count<100; count+) Strcount=rand0; sort(Str); for (count=0; count<100; count+) if (count%10=0) putchar('n'); printf("%3d ", Strcount); getchar; return 0; /*fun.h*/ #include<stdio.h> #include<stdlib.h> int rand0(void); void sort(int *str); /*fun.c*/ #include<stdio.h> #include"rand0.h" int rand0(void) intnum; num=rand%10+1; returnnum; void sort(int *str) inti, j, temp; for (i=0; i<100; i+) for (j=0; j<100-i-1; j+) if (strj<strj+1) temp=strj; strj=strj+1; strj+1=temp; 6. #include<stdio.h> #include<stdlib.h> int rand0; int main(void) intStr10=0; int count; int value; for(count=0; count<1000; count+) value=rand0; Strvalue-1+; for (count=0; count<10; count+) printf("%3d ", Strcount); getchar; return 0; int rand0 intnum; num=rand%10+1; returnnum; 7. /*main.c*/ #include<stdio.h> #include<stdlib.h> #include<time.h> #include"diceroll.h" int main(void) int dice, roll; int sides, sets; int status; inti; srand( (unsignedint) time(0) ); printf("Enter the number of sets; enter q to stop.n"); while(scanf("%d", &sets)=1 && sets>0) if (sets='q') break; printf("Enter the number of sides per die, 0 to stop.n"); if(scanf("%d", &sides)=1 && sides>0) printf("How many dice?n"); if( (status =scanf("%d", &dice)!=1) if (status=EOF) break; else printf("you should hane entered an integer."); printf(" Let's begin again.n"); while(getchar!='n') continue; printf("How many side? enter 0 to stop.n"); continue; printf("Here are %d sets of %d %d-sided throws.n", sets, dice, sides); for (i=0; i<sets; i+) roll=roll_n_dice(dice, sides); printf("%d ", roll ); putchar('n'); printf("Enter the number of sets; enter q to stop.n"); printf("The rollem function was called %d times.n", roll_count); printf("GOOD FORTUNE TO YOU!n"); getchar; return 0; /*diceroll.h*/ externintroll_count; introll_n_dice(int dice, int sides); /*diceroll.c*/ #include"diceroll.h" #include<stdio.h> #include<stdlib.h> introll_count=0; staticintrollem(intsides) int roll; roll=rand%sides+1; roll_count+; return roll; introll_n_dice(intdice, intsides) int d; int total=0; if(sides<2) printf("Need at least 2 sides.n"); return -2; if (dice<1) printf("Need at least 1 die.n"); return -1; for (d=0; d<dice; d+) total +=rollem(sides); return total; 8. #include<stdio.h> #include<stdlib.h> int *make_array(intelem, intval); voidshow_array(constintar, int n); int main(void) int *pa; int size; int value; printf("enter the number od elements: "); while(scanf("%d", &size)=1 && size>0) printf("enter the initialization value: "); scanf("%d", &value); pa=make_array(size, value); if (pa) show_array(pa, size); free(pa); printf("enter the number of elements (<1 to quit): "); printf("Done.n"); getchar; return 0; int *make_array(intelem, intval) int *ptd; inti; ptd=(int *) malloc(elem* sizeof(double); for (i=0; i<elem; i+) ptdi=val; returnptd; voidshow_array(constintar, intn) inti; for (i=0; i<n; i+) if (i%8=0) putchar('n'); printf("%3d ", ari); putchar('n'); 9. #include<stdio.h> #include<stdlib.h> #include<string.h> int main(void) intnum, i; char *ptd; char *temp; printf("How many words you wish to enter? "); while ( scanf("%d", &num) =1 &&num!=0) ptd=(char*)malloc(num*sizeof(char *); printf("Enter %d words now:n", num); temp=(char*) malloc(100 * sizeof(char); for (i=0; i<num; i+) scanf("%s", temp); *(ptd+i)=temp; printf("%sn", *(ptd+i); free(ptd); free(temp); printf("How many words you wish to enter? "); getchar; return 0;