C语言程序设计教程习题答案总主编杨路明主审郭浩志文件摘自CSDN习题11、算法描述主要是用两种基本方法：第一是自然语言描述，第二是使用专用工具进行算法描述2、c语言程序的结构如下：1、c语言程序由函数组成，每个程序必须具有一个main函数作为程序的主控函数。
2、"/*"与"*/"之间的内容构成c语言程序的注释部分。
3、用预处理命令#include可以包含有关文件的信息。
4、大小写字母在c语言中是有区别的。
5、除main函数和标准库函数以外，用户可以自己编写函数，程序一般由多个函数组成，这些函数制定实际所需要做的工作。
例如：void main(){int a,b,c,s;a=8;b=12;c=6;s=a+b*c;printf("s=%d\n",s);}3、c语言的特点：1、c语言具有结构语言的特点，程序之间很容易实现段的共享；2、c语言的主要结构成分为函数，函数可以在程序中被定义完成独立的任务，独立地编译成代码，以实现程序的模块化。
3、c语言运算符丰富，运算包含的范围很广；4、c语言数据类型丰富。
5、c语言允许直接访问物理地址，即可直接对硬件进行操作，实现汇编语言的大部分功能；6、c语言语法限制不太严格，程序设计自由度大，这样是c语言能够减少对程序员的束缚；7、用c语言编程，生成的目标代码质量高，程序执行效率高，可移植性好；4、合法标识符：AB12、leed_3、EF3_3、_762、PAS、XYZ43K2不合法标识符：a*b2、8stu、D.K.Jon、if、ave#xy、#_DT5、C.D5、F2:将当前编辑器中文件存盘F10:调用主菜单F4:程序运行到光标所在行Ctrl+F9:当前编辑环境下，进行编译、连接且运行程序；Alt+F5:将窗口切换到DOS下，查看程序运行结果6、(1):********************welcome youvery good********************(2):please input three number;5,7,8max number is:87、main8、User screen、Alt+F59、标识符必须是字母或下划线开头，大小写字母含义不同。
由数字、字母和下划线组成；关键字是一种语言中规定具有特定含义的标识符。
关键字不能作为变量或函数名来使用，用户只能根据系统的规定使用它们。
10、选择主菜单File项下拉子菜单中Save项或直接按F2键存盘。
习题21、符合C语法规定的常数为：0x1e、"ab\n"、1.e52、(1):错误如下：int x,y=5,z=5,aver;x=7;aver = (x+y+x)/3;结果如下：A VER=5(2):错误如下：char c1='a',c2='b',c3='c';printf("a=%db=\'%c\'\"end\"\n",a,b);结果如下：a=3b='A'"end"aabcc abc3、4、(1):9,11,9,10(2):3,1,0,0(3):11,19,31,15、(1):0(2):0(3):9.500000(4):90(5):10(6):10(7):65(8):4(9):4.500000(10):1(11):0(12):20(13):06、(5)7、求x的绝对值8、c>(max=a>b?a:b)?c:max;9、B10、D习题31、输入函数scanf的参数错误，应该为：scanf("%f",&k);2、|1234 1234 |3、ff104、1,3,15、原字符串左边加空格再加字符串本省，字符个数总和为5个6、scanf("%d,%d,%c,%c",&a1,&a2,&c1,&c2);7、printf("a+b=%d\n",a+b);printf("a-b=%d\n",a-b);printf("a*b=%d\n",a*b);printf("a/b=%d\n",a/b);printf("(float)a/b=%f\n",(float)a/b);printf("a%b=%d\n",a%b);8、void main(){float r;float s,c;printf("please input the number:");scanf("%f",&r);if(r>=0){s = 3.14*r*r;c = 2*3.14*r;printf("s = %f, c = %f\n",s,c);}elseprintf("you input number is error!");}9、void main(){int n;printf("please input the number:");scanf("%d",&n);if(n>=100 && n <= 999)printf("%d%d%d",n%10,(n/10)%10,n/100);elseprintf("you input number is error!");}10、void main(){int i,j,k;scanf("%d,%d,%d",&i,&j,&k);((i%2 != 0?1:0) + (j%2 != 0?1:0)+(k%2 != 0?1:0)) == 2?printf("YES\n"):printf("NO\n");}11、void main(){char a;scanf("%c",&a);printf("%c,%c,%c",a-1,a,a+1);printf("%d,%d,%d",a-1,a,a+1);}12、void main(){float a,b,c,s,Area;scanf("%f,%f,%f",&a,&b,&c);if(a+b > c || a+c > b || b+c >a){s = (a+b+c)/2;Area = sqrt(s*(s-a)*(s-b)*(s-c));printf("%f\n",Area);}elseprintf("you input the number is error!\n");}习题4 1：02：203：(x<30&&x>20)||(x<-100)4: ***a=25,b=14,c=16***5: 376: if(a<=b) printf("1");else printf("2");7、#include<stdio.h>void main(){ char a,b,t1,t2;scanf("%c,%c",&a,&b);t1=a>b?a:b;t2=a<b?a:b;if((t1-t2)%2==0)printf("%c,%c",a+1,b+1);else printf("%c,%c",a-1,b-1);getch();}8、#include<stdio.h>void main(){ int temp1=0,temp2=0,x,y,i=1;printf("Please input (x,y): ");scanf("%d,%d",&x,&y);while((i*y)<=x){ if(x==(i*y)) {temp1=1;break;}temp2=i;i++;}if(temp1)printf("%d / %d = %d",x,y,i);elseprintf("%d / %d---> shang=%d,yushu=%d",x,y,temp2,x-y*temp2);getch();}9、#include<stdio.h>void main(){ float x,y,m=0,n=0;scanf("%f,%f",&x,&y);n=(x-2)*(x-2);m=(y-2)*(y-2);if((m+n)<=1)printf("(%.3f,%.3f)In the yuan",x,y);elseprintf("(%.3f,%.3f)out of the yuan",x,y);getch();}10、#include<stdio.h>void main(){ int temp=0,month,year;printf("Please input (year,month): ");scanf("%d,%d",&year,&month);if((year%400==0)||(year%4==0&&year%100!=0))temp=1;if(month==2){ if(temp)printf("%d year %d month have 29 ",year,month);else printf("%d year %d month have 28 ",year,month);}else if(month%2==0)printf("%d year %d month have 30 ",year,month);else printf("%d year %d month have 31 ",year,month);getch();}11、switch(a/10){ case 5:m=4;break;case 4:m=3;break;case 3:m=2;break;case 2:m=1;break;default:m=5;}12、方法一：#include<stdio.h>void main(){ int x,y;scanf("%d",&x);if(x<0&&x>-5)y=x-1;else if(x==0)y=x;else if(x>0&&x<8)y=x+1;printf("%d",y);getch();}方法二：#include<stdio.h>void main(){ int x,y;scanf("%d",&x);if(x<8&&x>-5){ if(x==0)y=x;else if(x>0&&x<8) y=y=x+1;else y=x-1;printf("%d",y);}else printf("Input error!!!");getch();}方法三：#include<stdio.h>void main(){ int x,y,i;scanf("%d",&x);if(x<8&&x>-5){ if(x==0)i=1;else if(x>0&&x<8) i=2;else i=3;}else i=4;switch(i){ case 1:y=x;printf("%d",y);break;case 2:y=x+1;printf("%d",y);break;case 3:y=x-1;printf("%d",y);break;case 4:printf("Input error!!");break;}getch();}习题51、void main(){int n,value;int i,count=0;float average = 0;long int sum = 0;scanf("%d",&n);for(i = 0; i < n; i++){scanf("%d",&value);if(value%2 == 0){sum+=value;count++;}}average = sum / (float)count;printf("the average is %f\n",average);}2、#include "stdio.h"void main(){char ch;int zm = 0, sz = 0;ch = getchar();while(ch != '*'){if((ch >= 'A' && ch <= 'Z') || (ch >= 'a' && ch < 'z') )zm++;if(ch >= '0' && ch <= '9')sz++;ch = getchar();}printf("zm = %d ; sz = %d\n",zm,sz);}3、void main(){long i_value;int sum = 0;int temp = 0;scanf("%ld",&i_value);if(i_value < 0) {printf("you input the int is error!\n");return;} for(;;){temp = i_value%10;i_value = i_value/10;sum+=temp;printf("%d+",temp);if(i_value == 0)break;}printf("\b=%d\n",sum);}4、#include "stdio.h"void main(){char ch;ch = getchar();while(ch != '.'){if((ch >= 'A' && ch <= 'Z')){ch = ch + 32;putchar(ch);}else if((ch >= 'a' && ch < 'z') ){ch = ch - 32;putchar(ch);}else{putchar(ch);}ch = getchar();}printf("\n");}5、void main(){float sum = 200;int count = 0;for(;;){sum = sum+ sum*0.045;count++;if(sum > 500)break;}printf("the %d years later complete!\n",count);}6、void main(){int i,temp=0,bit=0;for(i = 1 ; i <= 999; i++){if(i%3 == 0){temp = i;for(;temp != 0;){bit = temp%10;if(bit == 5){printf("%d,",i);break;}temp = temp/10;}}}printf("\b \n");}7、#include <stdio.h>int main(void){int steps = 29, i = 1;while ( steps % 7 ){steps = (30 * ++i) - 1;}printf("Total steps: %d\n", steps);return 0;}8、main(){int i,j,k,n;printf("the narcissus number is:\n");for(n=100;n<1000;n++){i=n/100;j=n/10-i*10;k=n%10;if(i*i*i+j*j*j+k*k*k==n) printf("%d\n",n); }}9、main(){ float i,j,temp,n,sum;int t;i=2;j=1;sum=0;scanf("%d",&t);for(n=1;n<=t;n++){sum=sum+i/j;temp=i;i=i+j;j=temp;}printf("2/1+3/2+5/3+8/5+13/8+...=%f\n",sum); }10、void main(){int nWidth,a,b;scanf("%d",&nWidth);for(a=(nWidth%2);a<=nWidth;a+=2){for(b=0;b<nWidth;b++){char chOut =' ';int nleft =(nWidth -a)/2;int nright = (nWidth+a)/2;if(b>=nleft&&b<nright){chOut ='*';}printf("%c",chOut);}printf("\n");}}11、void main(){int i=1,j=1;for(i=1;i<=9;i++){for(j=1;j<=i;j++)printf("%d*%d=%d",i,j,i*j);printf("\n")}}12、#include "stdio.h"void main(){char c;//count1是正数的个数//count2是负数的个数int count1=0,count2=0;//sum1是正数之和//sum2是负数之和int sum1=0,sum2=0;int flage = 0;c=getchar();while(c != '*'){if(c == '-')flage = 1;if(flage == 0){sum1+=(c-48);count1++;}else{if(c != '-'){sum2-=(c-48);flage=0;count2++;}}c = getchar();}printf("%d,%d\n",count1,count2);printf("%f,%f\n",sum1/count1,sum2/count2); }13、void main(){int i,j;int s = 0;for(i = 100 ; i <= 999; i++){s = 0;for(j=1; j < i-1 ; j++){if( i%j == 0 ) s = s + j;}if(s == i)printf("%5d",i);}}14、#include <stdio.h>#include <math.h>void main(){int n;long k = 1;float e = 1;n = 1;clrscr();while ( fabs(1.0/k) >= 0.000001){n++;e = e+ 1.0/k;k = k * n;}printf("%f\n",e);}15、#include "math.h"main(){float x0,x1,x2,f0,f1,f2;x1=-10;f1=2*x1*x1*x1-4*x1*x1+3*x1;x2=10;f2=2*x2*x2*x2-4*x2*x2+3*x2;do{ x0=(x1+x2)/2;f0=2*x0*x0*x0-4*x0*x0+3*x0;if((f0*f1)<0){x2=x0; f2=f0;}else{x1=x0; f1=f0;}}while(fabs(f0)>1e-6);printf("______2*x*x*x-4*x*x+3*x=0______\n");printf("the root is %f\n",x0);}习题61、#include<stdio.h>int divisor(int a,int b){ int r;while((r=a%b)!=0){ a=b;b=r;}return b;}int multiple(int a,int b){ int d;d=divisor(a,b);return a*b/d;}void main(){ int a,b,c,d;printf("intput (a,b): ");scanf("%d,%d",&a,&b);c=divisor(a,b);d=multiple(a,b);printf("\ndivisor=%d\t\tmultiple=%d",c,d);}2、#include<stdio.h>void tongji(char a[]){ int b[3]={0,0,0},i=0;while(a[i]!='\0'){ if((a[i]<=90&&a[i]>=65)||(a[i]<=122&&a[i]>=97))b[0]++;else if(a[i]<=57&&a[i]>=48)b[1]++;elseb[2]++;i++;}printf("zimu have: %d; shuzi have: %d; qita have: %d",b[0],b[1],b[2]);getch();}void main(){ char a[100];printf("Please input a string: ");gets(a);tongji(a);}3、#include<stdio.h>int flower(int n){ int x=0,i,j,k;i=(n%10);j= (n/10%10);k=(n/100);x=i*i*i+j*j*j+k*k*k;if(x==n) return 1;else return 0;}void main(){ int i,n;printf("Please intput n: ");scanf("%d",&n);if(n>999||n<100)printf("Input error!!!");else{ for(i=100;i<n;i++)if(flower(i))printf("%d ",i);}getch();}4、#include<stdio.h>#define SW AP(a,b) t=b;b=a;a=t;main(){ float x,y,t;printf("Enter two number (x,y): ");scanf("%f,%f",&x,&y);SWAP(x,y);printf("\n\nExchanged:x=%f,y=%f",x,y);getch();}5、#include<stdio.h>int fib(int n){ int p;if(n==0) p=0;else if(n==1) p=1;else p=fib(n-1)+fib(n-2);return p;}void main(){ int n;printf("Please input fib: ");scanf("%d",&n);printf("\n\nfibonacci=%d",fib(n)); }6、#include<stdio.h>long fac(int n){ long f;if(n==0) f=1;else f=n*fac(n-1);return f;}void main(){ int m,n;long f;printf("Please input (m,n): ");scanf("%ld,%ld",&m,&n);f=fac(n+m)+fac(n);printf("\n\nfibonacci=%ld",f);}7、#include<stdio.h>void list(){ int i,j;for(i=1;i<=9;i++){ for(j=1;j<=i;j++)printf("%d*%d=%d ",i,j,i*j);printf("\n");}}void main(){ list();}8、#include<stdio.h>int he(int n){ int i,s=0;for(i=1;i<n;i++)if(n%i==0)s+=i;return s;}void main(){ int i,j;for(i=1;i<30000;i++){for(j=1;j<30000;j++)if((he(i)==j)&&(he(j)==i)&&(i!=j))printf("%d<--->%d ",i,j);}}9、#include<stdio.h>#define max 100struct work{ long sid;char name[15];}worker[max];int size=0;struct work *set_list(){ do{ printf("\n\nPlease input (sid,name): ");scanf("%ld,%s",&worker[size].sid,worker[size].name);size++;}while(worker[size-1].sid!=0);return worker;}void paixu(struct work a[]){ int i,j,k;long t;char v[15];for(i=0;i<size-1-2;i++){ k=i;for(j=i;j<size-2;j++)if(a[i].sid>a[j].sid)k=j;if(k!=i){ t=a[i].sid; a[i].sid=a[j].sid; a[j].sid=t;strcpy(v,a[i].name);strcpy(a[i].name,a[j].name);strcpy(a[j].name,v);}}for(i=0;i<=size-2;i++)printf("sid: %ld\tname:%s\n\n",a[i].sid,a[i].name);getch();}void select(struct work a[]){ int i=0,found=1;long num;printf("Input select sid: ");scanf("%ld",&num);for(i=0;i<=size-2;i++){ if(a[i].sid==num){ found=0;printf("%ld: %s",num,a[i].name);break;}}if(found)printf("\n\nNO this sid!!!");getch();}void main(){ struct work *p;p=set_list();paixu(p);select(p);}10、#include<stdio.h>float jiecheng(int n){ long s=1;int i;for(i=1;i<=n;i++)s=s*i;return s;}float chengfang(float x,int n){ float s=1;int i;for(i=1;i<=n;i++)s=s*x;return s;}float f(float x,int n){ float s=1,t=0;int i=1,j=-1;for(i=1;i<=n;i++){ t=j*chengfang(x,2*i)/jiecheng(2*i);s+=t;j=j*j;}return s;}main(){ float s1=0,s2=0,s3=0,s4=0,x=5.6;int n=7;s1=f(x,n);s2=f(x+2.3,n);s3=f(x-3.2,n+3);s4=s1/(s2+s3);printf("%f",s4);习题71：（1） D（2） A（3） D（4） B（5） D2：（1）1 5 4 46 7 82 34（2）63333: （1）a[8]=data; k>=0 a[k]=temp break k<=8(2) "%s" str[i]<='Z' c[str[i]+26-'a']++ i+'a'4、/*题目：求一组成绩的平均分数以及高于平均分的成绩。
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