C语言程序设计 (何钦铭 颜晖 著) 高等教育出版社第三章 课后答案

1、练习32#include <stdio.h>void main()float x;int y;printf("Please Input x: ");scanf("%f",&x);if(x>0)y=1;else if(x=0)y=0;else y=-1;printf("sign(%f)=%dn",x,y);练习33#include <stdio.h>void main()int i,letter,digit,space,other;char ch;letter=digit=space=other=0

2、;printf("Please Input 15 charactors: ");for(i=1;i<=15;i+)ch=getchar();if(ch=' ' | ch='n')space+;else if(ch>='0' && ch<='9')digit+;else if(ch>='A' && ch<='Z') | (ch>='a' && ch<='z')l

3、etter+;else other+;printf("letters=%d,digits=%d,spaces=%d,others=%dn",letter,digit,space,other);练习36#include <stdio.h>void main()char ch;printf("Please Input grade (AE): ");ch=getchar();switch(ch)case 'A':printf("The score is between 90-100.n");break;case

4、'B':printf("The score is between 80- 89.n");break;case 'C':printf("The score is between 70- 79.n");break;case 'D':printf("The score is between 60- 69.n");break;case 'E':printf("The score is between 0- 59.n");break; default: prin

5、tf("Input error!n");break;练习37#include <stdio.h>void main()int i,ch;float price;for(i=1;i<=5;i+) printf("1 applesn"); printf("2 pearsn"); printf("3 orangesn"); printf("4 grapesn"); printf("0 Exitn"); printf("Please choice(04):

6、 ");scanf("%d",&ch);if(ch=0)break; switch(ch)case 1:price=3.0;break;case 2:price=2.5;break;case 3:price=4.1;break;case 4:price=10.2;break;default: price=0.0;break;printf("The price is %.1f.n",price);练习38#include <stdio.h>void main()int year;printf("Please inpu

7、t a year: ");scanf("%d",&year);if(year%4=0 && year%100!=0) | (year%400=0)printf("Yes.n");else printf("No.n");练习39#include <stdio.h>void main()int i,n,num=0;float score,total=0;printf("Please input numbers of student: ");scanf("%d&qu

8、ot;,&n);for(i=1;i<=n;i+) printf("Please input score #%d(0100): ",i);scanf("%f",&score);if(score>=60)num+;total=total+score;printf("The average score is %.2f.n",total/n); printf("The numbers of passing is %d.n",num);练习310#include <stdio.h>vo

9、id main()double x,y;printf("Please input x: ");scanf("%lf",&x);if(x>15)y=2.5*x-10.5;elseif(x<0)y=0;else y=4*x/3;printf("y=f(%lf)=%lfn",x,y);习题31#include <stdio.h>#include <math.h>void main()double a,b,c,s,area,perimeter;printf("Please input a,

10、b,c. : ");scanf("%lf%lf%lf",&a,&b,&c);if(a+b>c && b+c>a && a+c>b && a>0 && b>0 && c>0)s=(a+b+c)/2;area=sqrt(s*(s-a)*(s-b)*(s-c);perimeter=2*s;printf("perimeter=%lf,area=%lfn",perimeter,area);else printf(&q

11、uot;These sides do not correspond to a valid triangle.n");习题32#include <stdio.h>#include <math.h>void main()double salary,tax,rate;printf("Please salary.: ");scanf("%lf",&salary);if(salary<=850)rate=0;else if(salary<=1350)rate=5;else if(salary<=2850)

12、rate=10;else if(salary<=5850)rate=15;else rate=20;tax=rate*(salary-850)/100;printf("These tax is %.2lf.n",tax);习题34#include <stdio.h>void main()int i,n,numa,numb,numc,numd,nume;float score,total=0;numa=numb=numc=numd=nume=0;printf("Please input numbers of student: ");sca

13、nf("%d",&n);for(i=1;i<=n;i+) printf("Please input score #%d(0100): ",i);scanf("%f",&score);if(score<60)nume+;else if(score<70)numd+;else if(score<80)numc+;else if(score<90)numb+;else if(score<=100)numa+;total=total+score;printf("The average score is %.2f.n",total/n); printf("The numbers of grade A(90100) is %d.n",numa); printf("The numbers of grade B(8089) is %d.n",numb); printf("The numbers of grade C(7079) is %d.n",numc); printf("The numbers of grade D(6069) is %d.n",numd); printf(&