第八章 C语言习题及答案(第八章)
c语言-C程序设计(第四版)谭浩强_课后习题答案第8章
C程序设计(第四版)谭浩强_课后习题答案第8章第8章善于利用指针2208.1指针是什么2208.2指针变量2228.2.1使用指针变量的例子2228.2.2怎样定义指针变量2238.2.3怎样引用指针变量2248.2.4指针变量作为函数参数2268.3通过指针引用数组2308.3.1数组元素的指针2308.3.2在引用数组元素时指针的运算2318.3.3通过指针引用数组元素2338.3.4用数组名作函数参数2378.3.5通过指针引用多维数组2458.4通过指针引用字符串2558.4.1字符串的引用方式2558.4.2字符指针作函数参数2598.4.3使用字符指针变量和字符数组的比较2638.5指向函数的指针2668.5.1什么是函数指针2668.5.2用函数指针变量调用函数2668.5.3怎样定义和使用指向函数的指针变量2688.5.4用指向函数的指针作函数参数2708.6返回指针值的函数2748.7指针数组和多重指针2778.7.1什么是指针数组2778.7.2指向指针数据的指针2808.7.3指针数组作main函数的形参2828.8动态内存分配与指向它的指针变量2858.8.1什么是内存的动态分配2858.8.2怎样建立内存的动态分配2858.8.3void指针类型2878.9有关指针的小结288习题2918-1#include <stdio.h>int main(){ void swap(int *p1,int *p2);int n1,n2,n3;int *p1,*p2,*p3;printf("input three integer n1,n2,n3:");scanf("%d,%d,%d",&n1,&n2,&n3);p1=&n1;p2=&n2;p3=&n3;if(n1>n2) swap(p1,p2);if(n1>n3) swap(p1,p3);if(n2>n3) swap(p2,p3);printf("Now,the order is:%d,%d,%d\n",n1,n2,n3); return 0;}void swap(int *p1,int *p2){int p;p=*p1; *p1=*p2; *p2=p;}#include <stdio.h>#include <string.h>int main(){void swap(char *,char *);char str1[20],str2[20],str3[20];printf("input three line:\n");gets(str1);gets(str2);gets(str3);if(strcmp(str1,str2)>0) swap(str1,str2);if(strcmp(str1,str3)>0) swap(str1,str3);if(strcmp(str2,str3)>0) swap(str2,str3);printf("Now,the order is:\n");printf("%s\n%s\n%s\n",str1,str2,str3);return 0;}void swap(char *p1,char *p2){char p[20];strcpy(p,p1);strcpy(p1,p2);strcpy(p2,p);}8-3#include <stdio.h>int main(){ void input(int *);void max_min_value(int *);void output(int *);int number[10];input(number);max_min_value(number);output(number);return 0;}void input(int *number){int i;printf("input 10 numbers:");for (i=0;i<10;i++)scanf("%d",&number[i]);}void max_min_value(int *number){ int *max,*min,*p,temp;max=min=number;for (p=number+1;p<number+10;p++)if (*p>*max) max=p;else if (*p<*min) min=p;temp=number[0];number[0]=*min;*min=temp;if(max==number) max=min;temp=number[9];number[9]=*max;*max=temp; }void output(int *number){int *p;printf("Now,they are: ");for (p=number;p<number+10;p++)printf("%d ",*p);printf("\n");}8-4#include <stdio.h>int main(){void move(int [20],int,int);int number[20],n,m,i;printf("how many numbers?");scanf("%d",&n);printf("input %d numbers:\n",n);for (i=0;i<n;i++)scanf("%d",&number[i]);printf("how many place you want move?"); scanf("%d",&m);move(number,n,m);printf("Now,they are:\n");for (i=0;i<n;i++)printf("%d ",number[i]);printf("\n");return 0;}void move(int array[20],int n,int m){int *p,array_end;array_end=*(array+n-1);for (p=array+n-1;p>array;p--)*p=*(p-1);*array=array_end;m--;if (m>0) move(array,n,m);}8-5#include <stdio.h>int main(){int i,k,m,n,num[50],*p;printf("\ninput number of person: n="); scanf("%d",&n);p=num;for (i=0;i<n;i++)*(p+i)=i+1;i=0;k=0;m=0;while (m<n-1){if (*(p+i)!=0) k++;if (k==3){*(p+i)=0;k=0;m++;}i++;if (i==n) i=0;}while(*p==0) p++;printf("The last one is NO.%d\n",*p); return 0;}8-6#include <stdio.h>int main(){int length(char *p);int len;char str[20];printf("input string: ");scanf("%s",str);len=length(str);printf("The length of string is %d.\n",len); return 0;}int length(char *p){int n;n=0;while (*p!='\0'){n++;p++;}return(n);}8-7#include <stdio.h>#include <string.h>int main(){void copystr(char *,char *,int);int m;char str1[20],str2[20];printf("input string:");gets(str1);printf("which character that begin to copy?"); scanf("%d",&m);if (strlen(str1)<m)printf("input error!");else{copystr(str1,str2,m);printf("result:%s\n",str2);}return 0;}void copystr(char *p1,char *p2,int m){int n;n=0;while (n<m-1){n++;p1++;}while (*p1!='\0'){*p2=*p1;p1++;p2++;}*p2='\0';}8-8#include <stdio.h>int main(){int upper=0,lower=0,digit=0,space=0,other=0,i=0; char *p,s[20];printf("input string: ");while ((s[i]=getchar())!='\n') i++;p=&s[0];while (*p!='\n'){if (('A'<=*p) && (*p<='Z'))++upper;else if (('a'<=*p) && (*p<='z'))++lower;else if (*p==' ')++space;else if ((*p<='9') && (*p>='0'))++digit;else++other;p++;}printf("upper case:%d lower case:%d",upper,lower);printf(" space:%d digit:%d other:%d\n",space,digit,other); return 0;}8-9#include <stdio.h>int main(){void move(int *pointer);int a[3][3],*p,i;printf("input matrix:\n");for (i=0;i<3;i++)scanf("%d %d %d",&a[i][0],&a[i][1],&a[i][2]);p=&a[0][0];move(p);printf("Now,matrix:\n");for (i=0;i<3;i++)printf("%d %d %d\n",a[i][0],a[i][1],a[i][2]);return 0;}void move(int *pointer){int i,j,t;for (i=0;i<3;i++)for (j=i;j<3;j++){t=*(pointer+3*i+j);*(pointer+3*i+j)=*(pointer+3*j+i);*(pointer+3*j+i)=t;}}8-10-1#include <stdio.h>int main(){void change(int *p);int a[5][5],*p,i,j;printf("input matrix:\n");for (i=0;i<5;i++)for (j=0;j<5;j++)scanf("%d",&a[i][j]);p=&a[0][0];change(p);printf("Now,matrix:\n");for (i=0;i<5;i++){for (j=0;j<5;j++)printf("%d ",a[i][j]);printf("\n");}return 0;}void change(int *p){int i,j,temp;int *pmax,*pmin;pmax=p;pmin=p;for (i=0;i<5;i++)for (j=i;j<5;j++){if (*pmax<*(p+5*i+j)) pmax=p+5*i+j;if (*pmin>*(p+5*i+j)) pmin=p+5*i+j;}temp=*(p+12);*(p+12)=*pmax;*pmax=temp;temp=*p;*p=*pmin;*pmin=temp;pmin=p+1;for (i=0;i<5;i++)for (j=0;j<5;j++)if (((p+5*i+j)!=p) && (*pmin>*(p+5*i+j))) pmin=p+5*i+j;temp=*pmin;*pmin=*(p+4);*(p+4)=temp;pmin=p+1;for (i=0;i<5;i++)for (j=0;j<5;j++)if (((p+5*i+j)!=(p+4))&&((p+5*i+j)!=p)&&(*pmin>*(p+5*i+j)))pmin=p+5*i+j;temp=*pmin;*pmin=*(p+20);*(p+20)=temp;pmin=p+1;for (i=0;i<5;i++)for (j=0;j<5;j++)if (((p+5*i+j)!=p) && ((p+5*i+j)!=(p+4)) && ((p+5*i+j)!=(p+20)) && (*pmin>*(p+5*i+j)))pmin=p+5*i+j;temp=*pmin;*pmin=*(p+24);*(p+24)=temp;}8-10-2#include <stdio.h>int main(){void change(int *p);int a[5][5],*p,i,j;printf("input matrix:\n");for (i=0;i<5;i++)for (j=0;j<5;j++)scanf("%d",&a[i][j]);p=&a[0][0];change(p);printf("Now,matrix:\n");for (i=0;i<5;i++){for (j=0;j<5;j++)printf("%d ",a[i][j]);printf("\n");}return 0;}void change(int *p) //交换函数{int i,j,temp;int *pmax,*pmin;pmax=p;pmin=p;for (i=0;i<5;i++) //找最大值和最小值的地址,并赋给pmax,pmin for (j=i;j<5;j++){if (*pmax<*(p+5*i+j)) pmax=p+5*i+j;if (*pmin>*(p+5*i+j)) pmin=p+5*i+j;}temp=*(p+12); //将最大值与中心元素互换*(p+12)=*pmax;*pmax=temp;temp=*p; //将最小值与左上角元素互换*p=*pmin;*pmin=temp;pmin=p+1;//将a[0][1]的地址赋给pmin，从该位置开始找最小的元素for (i=0;i<5;i++) //找第二最小值的地址赋给pminfor (j=0;j<5;j++){if(i==0 && j==0) continue;if (*pmin > *(p+5*i+j)) pmin=p+5*i+j;}temp=*pmin; //将第二最小值与右上角元素互换*pmin=*(p+4);*(p+4)=temp;pmin=p+1;for (i=0;i<5;i++) //找第三最小值的地址赋给pminfor (j=0;j<5;j++){if((i==0 && j==0) ||(i==0 && j==4)) continue;if(*pmin>*(p+5*i+j)) pmin=p+5*i+j;}temp=*pmin; // 将第三最小值与左下角元素互换*pmin=*(p+20);*(p+20)=temp;pmin=p+1;for (i=0;i<5;i++) // 找第四最小值的地址赋给pminfor (j=0;j<5;j++){if ((i==0 && j==0) ||(i==0 && j==4)||(i==4 && j==0)) continue;if (*pmin>*(p+5*i+j)) pmin=p+5*i+j;}temp=*pmin; //将第四最小值与右下角元素互换*pmin=*(p+24);*(p+24)=temp;}8-11-1#include <stdio.h>#include <string.h>int main(){void sort(char s[][6]);int i;char str[10][6];printf("input 10 strings:\n");for (i=0;i<10;i++)scanf("%s",str[i]);sort(str);printf("Now,the sequence is:\n"); for (i=0;i<10;i++)printf("%s\n",str[i]);return 0;}void sort(char s[10][6]){int i,j;char *p,temp[10];p=temp;for (i=0;i<9;i++)for (j=0;j<9-i;j++)if (strcmp(s[j],s[j+1])>0){strcpy(p,s[j]);strcpy(s[j],s[+j+1]);strcpy(s[j+1],p);}}8-11-2#include <stdio.h>#include <string.h>int main(){void sort(char (*p)[6]);int i;char str[10][6];char (*p)[6];printf("input 10 strings:\n");for (i=0;i<10;i++)scanf("%s",str[i]);p=str;sort(p);printf("Now,the sequence is:\n"); for (i=0;i<10;i++)printf("%s\n",str[i]);return 0;}void sort(char (*s)[6]){int i,j;char temp[6],*t=temp;for (i=0;i<9;i++)for (j=0;j<9-i;j++)if (strcmp(s[j],s[j+1])>0){strcpy(t,s[j]);strcpy(s[j],s[+j+1]);strcpy(s[j+1],t);}}8-12#include <stdio.h>#include <string.h>int main(){void sort(char *[]);int i;char *p[10],str[10][20];for (i=0;i<10;i++)p[i]=str[i];printf("input 10 strings:\n");for (i=0;i<10;i++)scanf("%s",p[i]);sort(p);printf("Now,the sequence is:\n"); for (i=0;i<10;i++)printf("%s\n",p[i]);return 0;}void sort(char *s[]){int i,j;char *temp;for (i=0;i<9;i++)for (j=0;j<9-i;j++)if (strcmp(*(s+j),*(s+j+1))>0){temp=*(s+j);*(s+j)=*(s+j+1);*(s+j+1)=temp;}}8-13#include<stdio.h>#include<math.h>int main(){float integral(float(*)(float),float,float,int);//对integarl函数的声明float fsin(float); //对fsin函数的声明float fcos(float); //对fcos函数的声明float fexp(float); //对fexp函数的声明float a1,b1,a2,b2,a3,b3,c,(*p)(float);int n=20;printf("input a1,b1:");scanf("%f,%f",&a1,&b1);printf("input a2,b2:");scanf("%f,%f",&a2,&b2);printf("input a3,b3:");scanf("%f,%f",&a3,&b3);p=fsin;c=integral(p,a1,b1,n);printf("The integral of sin(x) is:%f\n",c);p=fcos;c=integral(p,a2,b2,n);printf("The integral of cos(x) is:%f\n",c);p=fexp;c=integral(p,a3,b3,n);printf("The integral of exp(x) is:%f\n",c);return 0;}float integral(float(*p)(float),float a,float b,int n){int i;float x,h,s;h=(b-a)/n;x=a;s=0;for(i=1;i<=n;i++){x=x+h;s=s+(*p)(x)*h;}return(s);}float fsin(float x){return sin(x);}float fcos(float x){return cos(x);}float fexp(float x){return exp(x);}8-14#include <stdio.h>int main(){void sort (char *p,int m);int i,n;char *p,num[20];printf("input n:");scanf("%d",&n);printf("please input these numbers:\n");for (i=0;i<n;i++)scanf("%d",&num[i]);p=&num[0];sort(p,n);printf("Now,the sequence is:\n");for (i=0;i<n;i++)printf("%d ",num[i]);printf("\n");return 0;}void sort (char *p,int m) // 将n个数逆序排列函数{int i;char temp, *p1,*p2;for (i=0;i<m/2;i++){p1=p+i;p2=p+(m-1-i);temp=*p1;*p1=*p2;*p2=temp;}}8-15#include <stdio.h>int main(){void avsco(float *,float *);void avcour1(char (*)[10],float *);void fali2(char course[5][10],int num[],float *pscore,float aver[4]); void good(char course[5][10],int num[4],float *pscore,float aver[4]); int i,j,*pnum,num[4];float score[4][5],aver[4],*pscore,*paver;char course[5][10],(*pcourse)[10];printf("input course:\n");pcourse=course;for (i=0;i<5;i++)scanf("%s",course[i]);printf("input NO. and scores:\n");printf("NO.");for (i=0;i<5;i++)printf(",%s",course[i]);printf("\n");pscore=&score[0][0];pnum=&num[0];for (i=0;i<4;i++){scanf("%d",pnum+i);for (j=0;j<5;j++)scanf("%f",pscore+5*i+j);}paver=&aver[0];printf("\n\n");avsco(pscore,paver); // 求出每个学生的平均成绩avcour1(pcourse,pscore); // 求出第一门课的平均成绩printf("\n\n");fali2(pcourse,pnum,pscore,paver); // 找出2门课不及格的学生printf("\n\n");good(pcourse,pnum,pscore,paver); // 找出成绩好的学生return 0;}void avsco(float *pscore,float *paver) // 求每个学生的平均成绩的函数{int i,j;float sum,average;for (i=0;i<4;i++){sum=0.0;for (j=0;j<5;j++)sum=sum+(*(pscore+5*i+j)); //累计每个学生的各科成绩average=sum/5; //计算平均成绩*(paver+i)=average;}}void avcour1(char (*pcourse)[10],float *pscore) // 求第一课程的平均成绩的函数{int i;float sum,average1;sum=0.0;for (i=0;i<4;i++)sum=sum+(*(pscore+5*i)); //累计每个学生的得分average1=sum/4; //计算平均成绩printf("course 1:%s average score:%7.2f\n",*pcourse,average1);}void fali2(char course[5][10],int num[],float *pscore,float aver[4])// 找两门以上课程不及格的学生的函数{int i,j,k,labe1;printf(" ==========Student who is fail in two courses======= \n"); printf("NO. ");for (i=0;i<5;i++)printf("%11s",course[i]);printf(" average\n");for (i=0;i<4;i++){labe1=0;for (j=0;j<5;j++)if (*(pscore+5*i+j)<60.0) labe1++;if (labe1>=2){printf("%d",num[i]);for (k=0;k<5;k++)printf("%11.2f",*(pscore+5*i+k));printf("%11.2f\n",aver[i]);}}}void good(char course[5][10],int num[4],float *pscore,float aver[4]) // 找成绩优秀学生(各门85以上或平均90分以上)的函数{int i,j,k,n;printf(" ======Students whose score is good======\n");printf("NO. ");for (i=0;i<5;i++)printf("%11s",course[i]);printf(" average\n");for (i=0;i<4;i++){n=0;for (j=0;j<5;j++)if (*(pscore+5*i+j)>85.0) n++;if ((n==5)||(aver[i]>=90)){printf("%d",num[i]);for (k=0;k<5;k++)printf("%11.2f",*(pscore+5*i+k));printf("%11.2f\n",aver[i]);}}}8-16#include <stdio.h>int main(){char str[50],*pstr;int i,j,k,m,e10,digit,ndigit,a[10],*pa;printf("input a string:\n");gets(str);pstr=&str[0]; /*字符指针pstr置于数组str 首地址*/pa=&a[0]; /*指针pa置于a数组首地址*/ndigit=0; /*ndigit代表有多少个整数*/i=0; /*代表字符串中的第几个字符*/j=0;while(*(pstr+i)!='\0'){if((*(pstr+i)>='0') && (*(pstr+i)<='9'))j++;else{if (j>0){digit=*(pstr+i-1)-48; /*将个数位赋予digit*/k=1;while (k<j) /*将含有两位以上数的其它位的数值累计于digit*/{e10=1;for (m=1;m<=k;m++)e10=e10*10; /*e10代表该位数所应乘的因子*/digit=digit+(*(pstr+i-1-k)-48)*e10; /*将该位数的数值\累加于digit*/k++; /*位数K自增*/}*pa=digit; /*将数值赋予数组a*/ndigit++;pa++; /*指针pa指向a数组下一元素*/j=0;}}i++;}if (j>0) /*以数字结尾字符串的最后一个数据*/ {digit=*(pstr+i-1)-48; /*将个数位赋予digit*/k=1;while (k<j) /* 将含有两位以上数的其它位的数值累加于digit*/{e10=1;for (m=1;m<=k;m++)e10=e10*10; /*e10代表位数所应乘的因子*/digit=digit+(*(pstr+i-1-k)-48)*e10; /*将该位数的数值累加于digit*/k++; /*位数K自增*/}*pa=digit; /*将数值赋予数组a*/ndigit++;j=0;}printf("There are %d numbers in this line, they are:\n",ndigit);j=0;pa=&a[0];for (j=0;j<ndigit;j++) /*打印数据*/printf("%d ",*(pa+j));printf("\n");return 0;}8-17#include<stdio.h>int main(){int strcmp(char *p1,char *p2);int m;char str1[20],str2[20],*p1,*p2;printf("input two strings:\n");scanf("%s",str1);scanf("%s",str2);p1=&str1[0];p2=&str2[0];m=strcmp(p1,p2);printf("result:%d,\n",m);return 0;}int strcmp(char *p1,char *p2) //两个字符串比较函数{int i;i=0;while(*(p1+i)==*(p2+i))if (*(p1+i++)=='\0') return(0); //相等时返回结果0return(*(p1+i)-*(p2+i)); //不等时返回结果为第一个不等字符ASCII码的差值}8-18#include <stdio.h>int main(){char *month_name[13]={"illegal month","January","February","March","April", "May","June","july","August","September","October", "November","December"};int n;printf("input month:\n");scanf("%d",&n);if ((n<=12) && (n>=1))printf("It is %s.\n",*(month_name+n));elseprintf("It is wrong.\n");return 0;}8-19-1#include <stdio.h>#define NEWSIZE 1000 //指定开辟存区的最大容量char newbuf[NEWSIZE]; //定义字符数组newbufchar *newp=newbuf; //定义指针变量newp，指向可存区的始端char *new(int n) //定义开辟存区的函数new,开辟存储区后返回指针{if (newp+n<=newbuf+NEWSIZE) // 开辟区未超过newbuf数组的大小{newp+=n; // newp指向存储区的末尾return(newp-n); // 返回一个指针,它指向存区的开始位置}elsereturn(NULL); // 当存区不够分配时,返回一个空指针}8-19-2#include <stdio.h>#define NEWSIZE 1000char newbuf[NEWSIZE];char *newp=newbuf;void free(char *p) //释放存区函数{if (p>=newbuf && p< newbuf + NEWSIZE)newp=p;}8-20#define LINEMAX 20 /*定义字符串的最大长度*/int main(){int i;char **p,*pstr[5],str[5][LINEMAX];for (i=0;i<5;i++)pstr[i]=str[i]; /*将第i个字符串的首地址赋予指针数组pstr 的第i个元素*/ printf("input 5 strings:\n");for (i=0;i<5;i++)scanf("%s",pstr[i]);p=pstr;sort(p);printf("strings sorted:\n");for (i=0;i<5;i++)printf("%s\n",pstr[i]);}sort(char **p) /*冒泡法对5个字符串排序函数*/{int i,j;char *temp;for (i=0;i<5;i++){for (j=i+1;j<5;j++){if (strcmp(*(p+i),*(p+j))>0) /*比较后交换字符串地址*/{temp=*(p+i);*(p+i)=*(p+j);*(p+j)=temp;}}}return 0;}8-21#include<stdio.h>int main(){void sort(int **p,int n);int i,n,data[20],**p,*pstr[20];printf("input n:\n");scanf("%d",&n);for (i=0;i<n;i++)pstr[i]=&data[i]; //将第i个整数的地址赋予指针数组pstr 的第i个元素printf("input %d integer numbers:",n);for (i=0;i<n;i++)scanf("%d",pstr[i]);p=pstr;sort(p,n);printf("Now,the sequence is:\n");for (i=0;i<n;i++)printf("%d ",*pstr[i]);printf("\n");return 0;}void sort(int **p,int n){int i,j,*temp;for (i=0;i<n-1;i++){for (j=i+1;j<n;j++){if (**(p+i)>**(p+j)) //比较后交换整数地址{temp=*(p+i);*(p+i)=*(p+j);*(p+j)=temp;}}}}。
C语言第8章习题及答案
第八章用一个数组存放图书信息，每本书是一个结构，包括下列几项信息：书名、作者、出版年月、借出否，试写出描述这些信息的说明，并编写一个程序，读入若干本书的信息，然后打印出以上信息。
#include <>typedef struct{char Name[20];char Author[20];int Date_Year;int Date_Month;int loaned;} BOOK;#define N 10void main(){BOOK books[N];int i;for (i=0;i<N;i++){printf("Input Book's Name:");gets(books[i].Name);printf("Input Book's Author:");gets(books[i].Author);printf("Input Book's Year of Publishing:");scanf("%d",&books[i].Date_Year);printf("Input Book's Month of Publishing:");scanf("%d",&books[i].Date_Month);printf("Input Book's Status, 1-Loaned, 2-Keepin:");scanf("%d",&books[i].loaned);}for (i=0;i<N;i++){printf("Book: %s, Author: %s, Publishing:%d-%d, Status:%d\n", books[i].Name, books[i].Author, books[i].Date_Year, books[i].Date_Month, books[i].loaned);}}编写一个函数，统计并打印所输入的正文中的各个英文单词出现的次数，并按次数的递减顺序输出。
C语言程序设计(谭浩强)第八章详细课后答案
#if 0 //8.1#include<stdio.h>#include<math.h>void main(){int Common_divisor(int a,int b);int Common_mutiple(int m,int n);int result_1,result_2;int number_1,number_2;printf("Enter number_1 and number_2 value:");scanf("%d,%d",&number_1,&number_2);result_1 = Common_divisor(number_1,number_2);result_2 = Common_mutiple(number_1,number_2);printf("最大公约数：%d\n最小公倍数：%d\n",result_1,result_2); }int Common_divisor(int a,int b){int r = 1;while(r != 0){if(a>b){r = a%b;a = b;b = r;if(r == 0){return a;break;}}else{r = b%a;b = a;if(r == 0){return b;break;}a = r;}}}int Common_mutiple(int m,int n){int Common_divisor(int a,int b);int temp = 0,result = 0;temp = Common_divisor(m,n);result = (m*n)/temp;return result;}#endif#if 0 //8.2#include<stdio.h>#include<math.h>float result_1 =0.0,result_2 = 0.0;void main(){void Funvtion_1(float a,float b,float temp);void Function_2(float a,float b);float a,b,c;float temp;printf("Enter a,b,c value:");scanf("%f,%f,%f",&a,&b,&c);temp = b*b-4*a*c;if(temp > 0){Funvtion_1(a,b,temp);printf("x1 = %.3f,x2 = %.3f\n",result_1,result_2);}else if(temp < 0){printf("此函数没有根！\n");}else{Function_2(a,b);printf("x1 = x2 = %.3f\n",result_1);}}void Funvtion_1(float a,float b,float temp){result_1 = (-b+temp)/(2*a);result_2 = (-b-temp)/(2*a); }void Function_2(float a,float b) {result_1 = (-b)/(2*a);}#endif#if 0 //8.3#include<stdio.h>#include<math.h>void main(){void Prime(int n);int m;printf("Enter m value:");scanf("%d",&m);Prime(m);}void Prime(int n){int i = 0 ,k;k = (int)sqrt(n);for(i = 2; i <= k;i++){if(n%i == 0){break;}}if(i > k){printf("The number %d is a prime!\n",n);}else{printf("The number %d isn't a prime!\n",n);}}#endif#if 0#include<stdio.h>#include<math.h>int c[3][3];void main(){void Function(int b[3][3]);int a[3][3] = {{1,2,3},{4,5,6},{7,8,9}};int i,j;// int d[3][3];int k = sizeof(a[2])/sizeof(int); //列数int n = sizeof(a)/sizeof(int);for(i = 0; i < n/k;i++){for(j = 0;j < k;j++){printf("%d ",a[i][j]);}printf("\n");}Function(a);for(i = 0; i < k;i++){for(j = 0;j < n/k;j++){printf("%d ",c[i][j]);}printf("\n");}}void Function(int b[3][3]){int i = 0,j = 0;int k = sizeof(b[3])/sizeof(int);int n = sizeof(b)/sizeof(int);for(i = 0;i < k ;++i){for(j = 0;j < k; ++j){c[j][i] = b[i][j];}}}#endif#if 0#include<stdio.h>#include<math.h>#include<string.h>void main(){void Function(char a[100],char b[100]);char a[100];extern int b[100];int n = sizeof(a);printf("Enter a Array:");gets(a);Function(a,b);}void Function(char a[],char b[]){int i = 0;int n = sizeof(a)/sizeof(char);int m = strlen(a);for(i = 0; i < m;i++){b[i] = a[m-1-i];}//printf("put b Array:");//puts(b);for(i = 0;i < m;i++){putchar(b[i]);}}#endif#if 0 //8.6#include<stdio.h>#include<math.h>void main(){char a[20];char b[10];printf("Enter string a value:");gets(a);printf("Enter string b value:");gets(b);strcat(a,b);puts(a);}#endif#if 0 //8.6#include<stdio.h>#include<math.h>#include<string.h>int a[20];void main(){void Connect(char a[],char b[]);char b[10];printf("Enter string a value:");gets(a);printf("Enter string b value:");gets(b);Connect(a,b);// puts(a);printf("%s",a);}void Connect(char a[],char b[]) {int i = 0;int j = 0;while(a[i] != '\0'){i++;}while(b[j] != '\0'){a[i++] = b[j++];}// a[i] = '\0';}#endif#if 0//8.7#include<stdio.h>#include<math.h>#include<string.h>char b[100];void main(){void Research_vowel(char a[]);char a[50];printf("Enter string a value:");gets(a);Research_vowel(a);puts(b);}void Research_vowel(char a[]){int i = 0,j = 0;for(; i < strlen(a);i++){if(a[i] == 'a'|| a[i] == 'e' || a[i] == 'i' || a[i] == 'o' || a[i] == 'u'){b[j] = a[i];j++;}}#endif#if 0//8.8#include<stdio.h>#include<math.h>char a[4];void main(){void Divide(int n);int n = 0,i = 0;printf("Enter n value(<10000):");scanf("%d",&n);Divide(n);for(;i<4;i++){printf("%d ",a[i]);}printf("\n");}void Divide(int n)int i = 0,c = 0,b = 0,m = 1000;while(m >= 1){c = n/m;b = n%m;m = m/10;a[i] = c;n = b;i++;}}#endif#if 0//8.9#include<stdio.h>#include<math.h>#include<string.h>int m = 0,n = 0,r = 0,l = 0;void main(){void Research_number(char a[]);char a[50];int i = 0;printf("enter string value:");gets(a);/*for(;i<strlen(a);i++){printf("%c",a[i]);}*/puts(a);puts("");Research_number(a);printf("字母个数是：%d,数字个数是：%d,空格个数是：%d,其它：%d\n",m,n,r,l);}void Research_number(char a[]){int i = 0;for(i = 0;i<strlen(a);i++){if((a[i] >= 'a' && a[i] <= 'z') || (a[i] >= 'A' && a[i] <= 'Z')){m++;}else if(a[i] > 47 && a[i] < 58){n++;}else if(a[i] == 32){r++;}else{l++;}}}#endif#if 0 //8.10#include<stdio.h>#include<math.h>#include<string.h>void main(){void Array(char a[]);char b[20];printf("Enter b string(<20):");gets(b);printf("Longest word is : ");Array(b);}void Array(char a[]){int i = 0,place = 0,point = 0,length = 1; //point表示最长单词的开始位置place表示最长单词最后的一个位置int max = 0,j = 0;int flag = 0; //为0 时是空格为1时是单词max = length;for(i = 0;i<=strlen(a);i++){if(a[i] != ' ' && a[i] != '\0'){if(0 == flag){j = i;flag = 1;}elselength++; //这个题让我做的非常的难过以后要好好的复习}else{flag = 0;if(max < length){max = length;point = j;place = i;}length = 1;}}for(i = point;i <= place;i++){printf("%c",a[i]);}printf("\n");}/*int judge_words(char b[20]){int i = 0,flag = 1;for(i = 0;i < strlen(b); i++){if((a[i] >= 'a' && a[i] <= 'z') || (a[i] >= 'A' && a[i] <= 'Z')){flag = 1;}else{flag = 0;}}}*/#if 0 //8.11#include<stdio.h>#include<math.h>void main(){void bubbling(char a[]);char a[10];printf("enter string a value:");gets(a);bubbling(a);puts(a);}void bubbling(char a[]){int i = 0,j = 0;char temp;for(i = 0;i<strlen(a) - 1;i++){for( j = 0;j<strlen(a)-1-i;j++)if(a[j] > a[j+1]){temp = a[j];a[j] = a[j+1];a[j+1] = temp;}}}}#endif#if 0 //8.12#include<stdio.h>#include<math.h>void main(){float Function(float x);float x = 1.5,x1 = 0.0;x1 = Function(x);printf("%.3f\n",x1);}float Function(float x){float x1;float y,y1;while(fabs(y1)>=1e-6){x = x1;y1 = x*x*x+2*x*x+3*x+4;y = 3*x*x+4*x+3;x1 = x - (y1/y);}return x1;}#endif#if 0//8.13#include<stdio.h>#include<math.h>void main(){float p(float x,int n);float x = 0.0,result = 0.0;int n = 0;printf("Enter x and n value:");scanf("%f,%d",&x,&n);result = p(x,n);printf("p(x) value :%.3f\n",result);}float p(float x,int n){float y = 0.0;if(n == 0){y = 0;}else if(n == 1){y = x;}else{y = ((2*n-1)*x-p(x,n-1)-(n-1)*p(x,n-2))/n;}return y;}#endif#if 0//8.14#include<stdio.h>#include<math.h>int r = 0,l = 0;void main(){float* EStudent_aver(float scores[10][5]);float* EClass_aver(float scores[10][5]);float Maxscore(float scores[10][5]);float variance(float scores[10][5]);float scores[10][5] = {{76,43,46,73,46},{34,67,89,32,47},{31,68,73,16,87},{31,67,31,37,63},{16 ,37,61,67,86},{31,34,60,49,29},{89,89,87,87,98},{97,34,89,42,89},{45,67,34,18,64},{ 32,16,87,42,15}};float *Student_aver,*Class_aver,Student_max = 0.0,aver_variance = 0.0;int i = 0,j = 0,k = 0;/* char Student_name[] = {"Zhanghua Xiaoming Ligang Xiaotao Zhangsan Xiaoqiang CBC Baixu Gongcheng BOBO "};char score_name[] = {"Chinese Math English Chemitry WuLi"};printf("\t");for(i = 0;i < strlen(score_name);i++){printf("%c",score_name[i]);}puts("");for(i = 0;i < strlen(Student_name);i++){printf("%c",Student_name[i]);if(Student_name[i] == 32){for(j = 0;j < 5;j++){printf(" %.0f\t",scores[k][j]);}k++;puts("");}}*//* printf("\n");for(i = 0; i < 10;i++){for(j = 0;j < 5;j++){printf(" %.0f\t",scores[i][j]);}puts("");}*/// float scores[10][5];printf("NO. course1 course2 course3 course4 course5\n");for(i = 0;i < 10;i++){printf("No.%2d\t",i+1);for(j = 0;j < 5;j++){printf("%.2f\t ",scores[i][j]);}puts("");}Student_aver = EStudent_aver(scores);Class_aver = EClass_aver(scores);Student_max = Maxscore(scores);aver_variance = variance(scores);printf("Student_aver:\n");for(i = 0;i < 10;i++){printf("%.2f ",Student_aver[i]);}printf("\nClass_aver:\n");for(i = 0 ;i < 5;i++){printf("%.2f ",Class_aver[i]);}printf("\n");printf("The Max Score:\n %.2f Name: No.%d , Course: course%d\n",Student_max,r,l);printf("Student average Variance: \n %.2f\n",aver_variance);}float * EStudent_aver(float scores[10][5]){static float aver[10],sum = 0.0;int i = 0,j = 0;for(i = 0;i < 10;i++){for(j = 0; j < 5; j++){sum += scores[i][j];}aver[i] = sum/5;sum = 0;}return aver;}float* EClass_aver(float scores[10][5]) {static float aver_1[5],sum = 0.0;int i = 0,j = 0;for(j = 0;j<5;j++){for(i = 0;i<10;i++){sum +=scores[i][j];}aver_1[j] = sum/10;sum = 0;}return aver_1;}float Maxscore(float scores[10][5]) {int i = 0,j = 0;float max = scores[0][0];for(i = 0;i < 10;i++){for(j = 0;j < 5;j++){if(max < scores[i][j]){max = scores[i][j];r = i + 1;l = j + 1;}}}return max;}float variance(float scores[10][5]){float* EStudent_aver(float scores[10][5]);float s = 0.0;float sum_1 = 0.0,sum_2 = 0.0;float number_1 = 0.0,number_2 = 0.0;float* student_aver;int i = 0,j = 0;student_aver = EStudent_aver(scores);for(i = 0;i<10;i++){sum_1 += student_aver[i]*student_aver[i];sum_2 += student_aver[i];}number_1 = sum_1/10;number_2 = (sum_2/10)*(sum_2/10);s = number_1 - number_2;return s;}#endif#if 0 //测试static#include<stdio.h>#include<math.h>static j;void f1(){static i = 0;i++;}void f2(){j = 0;j++;}void main(){int k = 0;for(k = 0;k < 10;k++){f1();f2();}}#endif#if 0//8.16#include<stdio.h>#include<math.h>void main(){void Change(int n);int m = 0;printf("Enter ox number:");scanf("%x",&m);// printf("%d\n",m);Change(m);}void Change(int n){//int m;printf("十进制是: %d\n",n); }#endif#if 0//8.17#include<stdio.h>#include<math.h>void main(){void Function(int n);int m;printf("Input a integer:");scanf("%d",&m);Function(m);}void Function(int n){int i;/* if(n!=0){ch[i] = n%10;temp = n/10;i++;Function(temp);}else{ch[i] = 0;}return ch;*/i = n/10;if(i != 0){Function(i);}putchar(n%10+'0');putchar(32);}#endif#if 0 //今天是今年的多少天#include<stdio.h>#include<math.h>void main(){int i = 1,d = 0,sum = 0;int year,month,day;printf("Enter year and month and day(2012/08/19):");scanf("%d/%d/%d",&year,&month,&day);sum = day;for(;i<month;i++){switch(i){case 1:case 3:case 5:case 7:case 8:case 10:case 12: d = 31; break;case 2:if(year%400 == 0 || year%4 == 0 && year%100!=0){d = 29;}else{d = 28;}break;case 4:case 6:case 9:case 11: d = 30;break;}sum += d;}printf("The %d of The year dates!\n",sum); }#endif#if 0 //8.15#include<stdio.h>#define N 10void main(){void Enter_massage(char staff_name[N][10],int staff_number[N]);void Sort(char staff_name[N][10],int staff_number[N]);int middle_search(int staff_number[N],int number);int number,temp = 0;char staff_name[N][10];int staff_number[N];Enter_massage(staff_name,staff_number);//输入信息Sort(staff_name,staff_number);printf("Enter search staff_number:");scanf("%d",&number);temp = middle_search(staff_number,number);printf("The staff number is : %d\n",staff_number[temp]);printf("The staff name is : %s\n",staff_name[temp]);}void Enter_massage(char staff_name[N][10],int staff_number[N]) {int i;for(i = 0;i < N;i++){printf("Enter Staff number No.:");scanf("%d",&staff_number[i]);fflush(stdin);printf("Input staff name:");gets(staff_name[i]);}}void Sort(char staff_name[N][10],int staff_number[N]) {int i,j;int temp1;char temp[N][10];for(i = 0;i < N - 1; i++){for(j = 0;j < N - 1 - i; j++){if(staff_number[j]>staff_number[j+1]){temp1 = staff_number[j];strcpy(temp[j],staff_name[j]);staff_number[j] = staff_number[j+1];strcpy(staff_name[j],staff_name[j+1]);staff_number[j+1] = temp1;strcpy(staff_name[j+1],temp[j]);}}/*if(staff_number[i]<staff_number[i+1]){temp1 = staff_number[i];staff_number[i] = staff_number[i+1];staff_number[i+1] = temp1;}*/}for(i = 0;i < N;i++){printf("staff number is : %d\n",staff_number[i]);printf("staff name is %s\n",staff_name[i]);}}int middle_search(int staff_number[N],int number) //折半查找法！{int min = 0,high = 0,mid = 0;int i = 0;min = 0;high = N - 1;while(min <= high){mid = (min+high)/2;if(staff_number[mid] > number){high = mid - 1;}else if(staff_number[mid] < number){min = mid + 1;}else{return mid;}}}#endif/*fasdfa the world helloint flag=0;flag=1;//letterflag=0;//space*/#if 0 //有问题输出的是不对的！为什么指针值temp+1的值不是指向的name[1]这一行的首地址而是++后指向的是name[0]下一列的地址呢？#include<stdio.h>void main(){char name[5][10];char temp[5][10];int i = 0;// temp = &name[0];for(i = 0;i < 5;i++){gets(name[i]);strcpy(temp[i],name[i]);}for(i = 0;i < 5;i++){//puts(name[i]);puts(temp[i]);}}#endif#if 0 //看不懂的程序8.15 #define N 10find(a,b)int a[],b[];{int i,j,s,t,c[N][2];for(i=0;i<N;i++){c[i][1]=a[i];c[i][1]=i;} for(i=0;i<N;i++)for(j=0;j<N-i-1;j++)if(c[i][0]>c[i+1][0]){t=c[i][0];c[i][0]=c[i+1][0];c[i+1][0]=t;s=c[i][1];c[i][1]=c[i+1][1];c[i+1][1]=s;}for(i=0;i<N;i++)b[i]=c[i][1];return;}lookfor(h,k)int h[],k;{int i,j;for(i=0;i<N;i++)if(h[i]-k==0) j=i;return j;}main(){int number[N],x[N],i,j,u,p;char name[N][20];for(i=0;i<N;i++){gets(name[i]);scanf("%d",&number[i]);} scanf("%d",&p);find(number,x);u=lookfor(number,p);for(i=0;i<N;i++){printf("%d",number[i]);puts(name[x[i]]);}puts(name[x[u]]);}#endif#if 1 //16进制转换成10进制#include<stdio.h>#include<math.h>#define N 10int flag = 1;void main(){extern int sum;int convert(char str[],int n);char str[N];int s = 0,n = 0;puts("Enter 16 OX number:");gets(str);n = strlen(str);s = convert(str,n);if(1 == flag){printf("10 d number is : %d\n",s);}else{printf("The number isn't OX \n");}}int convert(char str[],int n){int i,j = 0;int sum = 0;for(i = n - 1;i > -1;i--,j++){if(str[i] > 47 && str[i] < 58){sum = sum + (str[i] - 48) * (int)pow(16,j);}else if(str[i] > 64 && str[i] < 71){sum = sum + (str[i] - 55)* (int)pow(16,j);}else if(str[i] > 96 && str[i] < 103){sum = sum + (str[i] - 87) * (int)pow(16,j);}else{flag = 0;}}return sum;}#endif#if 0#include<stdio.h>#include<math.h>void main(){printf("%d\n",(int)pow(2,0)); }#endif。
C语言程序设计课件源程序及习题答案第8章结构体和共用体及其应用
1
Y 调用函数fnGetKey() iKey=fnGetKey();
N iKey==LEFT||iKey==RIGHT
Y 输出left&right
iKey==UPPER||iKey==DOWN N
Y
输出up&down
iKey==ESC N
Y 结束
小结：
1．C最初引入共用体的目的，一是节省存储空间，另外是可以 将一种类型的数据不通过显式类型转换而作为另一种类型数据 使用，如问题8.9的解决方法。
试一试 问题8.5：
修改问题8.2，要求在函数中实现计算、 比较平均分并且显示平均分数较高的学 生信息的功能。
问题8.6：
修改问题8.4，在函数中将N个学生的数据输 入并统计总分和求出最高分的学生并显示。
主函数流程图
想一想
在问题8.3的代码中，如果要求对输入 数据对输入的年、月、日进行合法性校 验，比如年是在1989－2019年之间， 月是在1－12之间，日是1－30之间， 怎么解决？如果进一步要求根据月份而 确定每月的天数，又该怎么办呢
一般的引用形式为：
数组名[下标].成员名
问题8.4：试一试
一个学习小组有N名学生，学生的信息 包含学号、姓名、语文、数学、英语三 门课的成绩，从键盘上输入N名学生的 信息，要求统计总成绩并显示总分最高 的学生信息。
解题步骤
1. 以学生的信息数据项为成员，定义结 构体类型和相应的结构体数组
2. 循环输入每个学生的信息，统计总成 绩，存储在结构体数组中
练一练
尝试编写学生管理系统，定义学生信息 的结构体类型，分别用函数实现数据输 入、数据输出、计算每个人的平均分， 进行排序和成绩插入等操作。
C语言 2版 课后答案 八章
else strcat(c,q);
puts(c);
}
2、以下程序从键盘输入 10 个不相同的数到数组 a 中，再输入一个数到 x 中，在 a 中查 找与 x 值相同的元素所在的位置，填空完善该程序。。 #include <stdio.h>
void main( )
{
int a[11],x,i;
printf("Input 10 integers:\n");
院 学
}
范
int fun(char *p) {
int flag=1;
师 阳
绵 while(*p!='\0')
{
if(*p==' ')flag=1;
if(*p>='a'&&*p<='z'&&flag==1){*p-=32;flag=0;}
p++;
}
}
【解法二】 #include"stdio.h" main( ) {
char ch,str[80];
ww printf("Input string end by.: \n") ;
while((ch=getchar())!='.') str[i++]=ch;
str[i++]='.'; str[i]='\0';
坛 论
fun(str); puts(str); getch();
int flag=1;
char ch;
printf("Input string end by.: \n") ;
第八章 C语言习题及答案(第八章)
8-1 编写程序，将10个数34，3，29，63，70，16，85，82，90，93存放于一组数组中，求出这十个数的和及平均值。
解：#include "stdio.h"void main(){int a[10]={34,3,29,63,70,16,85.82,90,93};int i ,sum=0;float average ;for(i=0;i<10;i++){sum=sum+a[i] ;}average=sum/10.0;printf("sum=%d,average=%f\n",sum,average);}运行结果：sum=565,average=56.5000思考：数组有何特点？此问题如果不用数组进行处理将会怎样？8-2 编写程序，求存放于上题数组中10个数的最大值，最小值及所在的位置。
解：#include "stdio.h"void main(){int a[10]={34,3,29,63,70,16,85,82,90,93};int i,sum,max,min,d_max,d_min;max=min=a[0];d_max=d_min=0;for(i=1;i<10;i++){if(a[i]>max) {max=a[i];d_max=i;}if(a[i]<min) {min=a[i];d_min=i;}}printf("max=%d,a[%d]\n",max,d_max);printf("min=%d,a[%d]\n",min,d_min);}运行结果:max=93,a[9]Min=3,a[1]思考：数组a[i]中i的变化意味着什么？8-3 编写程序，从键盘读入50个数存放于一数组中，求出该数组中最大值、最小值及所在位置。
解：#include "stdio.h"void main(){float a[50],max,min;int i,d_max,d_min;for(i=0;i<50;i++)scanf("%f",&a[i]);max=min=a[0];d_max=d_min=0;for(i=1;i<50;i++){if(a[i]>max) {max=a[i];d_max=i;}if(a[i]<min) {min=a[i];d_min=i;}}printf("max=%d,a[%d]\n",max,d_max);printf("min=%d,a[%d]\n",min,d_min);}思考：此题中不用数组也可以处理吗?如果可以，区别之处在哪里？8-4将存放于上题数组中的50个数分别按升序，降序排序。
第8章习题参考答案
8.1#include<stdio.h>hcf(int u,int v) //求最大公约数{int a,b,t,r;if(u>v){t=u;u=v;v=t;}a=u;b=v;while((r=b%a)!=0){b=a;a=r;}return(a);}lcd(int u,int v,int h) //求最小公倍数{return(u*v/h);}void main(){int u,v,h,l;scanf("%d,%d",&u,&v);h=hcf(u,v);printf("H.C.F=%d\n",h); //输出最大公约数l=lcd(u,v,h);printf("L.C.D=%d\n",l);}8.3#include<stdio.h>#include<math.h>void main(){ int prime(int); //函数声明int number;scanf("%d",&number);if(prime(number)) printf("yes\n");else printf("no\n");}int prime(int number) //求素数的函数，注意返回值{ int flag=1,n,k;k=sqrt(number);for(n=2;n<k&&flag==1;n++)if(number%n==0)flag=0;return(flag);}8.5#include<stdio.h>#include<string.h>void main(){ void inverse(char str[]); //函数声明char str[100];scanf("%s",str);inverse(str);printf("%s\n",str);}void inverse(char str[]) //将字符串逆序存放{ char t; int i,j;for(i=0,j=strlen(str);i<strlen(str)/2;i++,j--){t=str[i]; str[i]=str[j-1]; str[j-1]=t;}}8.7#include<stdio.h>#include<string.h>void cpy(char s[],char c[]) //复制元音字母的函数{int i,j;for(i=0,j=0;s[i]!='\0';i++)if(s[i]=='a'||s[i]=='A'||s[i]=='e'||s[i]=='E'||s[i]=='i'|| s[i]=='I'||s[i]=='o'||s[i]=='O'||s[i]=='u'||s[i]=='U'){c[j]=s[i];j++;}c[j]='\0';}void main(){char str[80],c[80];gets(str);cpy(str,c);printf("\n%s\n",c);}8.8#include<stdio.h>#include<string.h>void insert(char str[]){int i;for(i=strlen(str);i>0;i--){str[i*2]=str[i];str[i*2-1]=' '; //插入空格}printf("%s\n",str);}void main(){char str[80];scanf("%s",str);insert(str);}8.9#include<stdio.h>#include<string.h>int alph,digit,space,others; //定义全局变量void count(char str[]){int i;for(i=0;str[i]!='\0';i++)if((str[i]>='a'&&str[i]<='z')||(str[i]>='A'&&str[i]<='Z'))alph++;else if(str[i]>='0'&&str[i]<='9')digit++;else if(str[i]==' ') space++;else others++;}void main(){char text[80];gets(text);alph=0,digit=0,space=0,others=0;count(text);printf("\nalph=%d,digit=%d,space=%d,others=%d\n",alph,digit,space,others); }8.16#include<stdio.h>#define MAX 1000void main(){ int htoi(char s[]); //函数声明int c,i=0,flag=0; char t[MAX];while((c=getchar())!='\0'&&i<MAX){if(c>='0'&&c<='9'||c>='A'&&c<='F'||c>='a'&&c<='f'){ flag=1; t[i++]=c;}else if(flag){t[i]='\0';printf("\nnumber=%d\n",htoi(t));break;}}}int htoi(char s[]) //十六进制转换成十进制{ int i,n=0;for(i=0;s[i]!='\0';i++){ if(s[i]>='0'&&s[i]<='9')n=n*16+s[i]-'0';if(s[i]>='a'&&s[i]<='f')n=n*16+s[i]-'a'+10;if(s[i]>='A'&&s[i]<='F')n=n*16+s[i]-'A'+10;}return(n);}8.18#include<stdio.h>static int day_tab[13]={0,31,28,31,30,31,30,31,31,30,31,30,31}; int sum_day(int month,int day) //累计天数{int i;for(i=1;i<month;i++)day+=day_tab[i];return(day);}int leap(int year) //判断是否闰年{int leap;leap=year%4==0&&year%100!=0||year%400==0;return(leap);}void main(){int year,month,day,days;scanf("\n%d,%d,%d",&year,&month,&day);days=sum_day(month,day);if(leap(year)&&(month>=3))days+=1;printf("days=%d\n",days);}。
C语言课后习题答案第八章
作业八：函数程序设计答案〔一〕选择题〔30分〕1．以下正确的函数定义形式是A__。
A）double fun(int x,int y)B）double fun(int x;int y)C）double fun(int x,int y);D）double fun(int x,y);2．以下正确的函数形式是D__。
A）double fun(int x,int y){ z=x+y; return z; }B）fun(int x,y){ int z; return z; }C）fun(x,y){ int x,y; double z; z=x+y; return z; }D）double fun(int x,int y){ double z; z=x+y; return z; }〔重要〕3．以下正确的说法是A__。
在C语言中A〕实参和及其对应的形参各占用独立的存储单元B〕实参和及其对应的形参共占用一个存储单元C〕只有当实参和及其对应的形参同名时才共占用存储单元D〕形参是虚拟的，不占用存储单元4．假设调用一个函数，且此函数中没有return语句，那么正确的说法是D__。
该函数A〕没有返回值B〕返回假设干个系统默认值C〕能返回一个用户所希望的函数值D〕返回一个不确定的值〔重要〕5．以下不正确的说法是B__。
C语言规定A〕实参可以是常量、变量或表达式B〕形参可以是常量、变量或表达式C〕实参可以为任意类型D〕形参应及其对应的实参类型一致6．C语言规定，简单变量做实参时，它和对应形参之间的数据传递方式是B__。
A）地址传递B）单向值传递C）由实参传给形参，再由形参传回给实参D）由用户指定传递方式7．以下程序有语法性错误，有关错误原因的正确说法是C__。
main()int G=5,k;void Prt_char();k=Prt_char(G);A）语句void prt_char();有错，它是函数调用语句，不能用void说明B）变量名不能使用大写字母C）函数说明和函数调用语句之间有矛盾D）函数名不能使用下划线8．C语言允许函数值类型缺省定义，此时该函数值隐含的类型是B__。
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8-1 编写程序，将10个数34，3，29，63，70，16，85，82，90，93存放于一组数组中，求出这十个数的和及平均值。
解：#include "stdio.h"void main(){int a[10]={34,3,29,63,70,16,85.82,90,93};int i ,sum=0;float average ;for(i=0;i<10;i++){sum=sum+a[i] ;}average=sum/10.0;printf("sum=%d,average=%f\n",sum,average);}运行结果：sum=565,average=56.5000思考：数组有何特点？此问题如果不用数组进行处理将会怎样？8-2 编写程序，求存放于上题数组中10个数的最大值，最小值及所在的位置。
解：#include "stdio.h"void main(){int a[10]={34,3,29,63,70,16,85,82,90,93};int i,sum,max,min,d_max,d_min;max=min=a[0];d_max=d_min=0;for(i=1;i<10;i++){if(a[i]>max) {max=a[i];d_max=i;}if(a[i]<min) {min=a[i];d_min=i;}}printf("max=%d,a[%d]\n",max,d_max);printf("min=%d,a[%d]\n",min,d_min);}运行结果:max=93,a[9]Min=3,a[1]思考：数组a[i]中i的变化意味着什么？8-3 编写程序，从键盘读入50个数存放于一数组中，求出该数组中最大值、最小值及所在位置。
解：#include "stdio.h"void main(){float a[50],max,min;int i,d_max,d_min;for(i=0;i<50;i++)scanf("%f",&a[i]);max=min=a[0];d_max=d_min=0;for(i=1;i<50;i++){if(a[i]>max) {max=a[i];d_max=i;}if(a[i]<min) {min=a[i];d_min=i;}}printf("max=%d,a[%d]\n",max,d_max);printf("min=%d,a[%d]\n",min,d_min);}思考：此题中不用数组也可以处理吗?如果可以，区别之处在哪里？8-4将存放于上题数组中的50个数分别按升序，降序排序。
解：#include "stdio.h"#define N 50void main(){float a[N] ,t;int i,j;for(i=0;i<N;i++)scanf("%f",&a[i]);/*按升序排序*/for(i=0;i<N;i++){for(j=i;j<N;j++)if(a[i]>a[j]) {t=a[i];a[i]=a[j];a[j]=t;}printf("%8.2f",a[i]);}printf("\n");/*按降序排序*/for(i=0;i<N;i++){for(j=i;j<N;j++)if(a[i]<a[j]) {t=a[i];a[i]=a[j];a[j]=t;}printf("%8.2f",a[i]);}printf("\n");}思考：此题中可以不用数组进行处理吗？（进一步理解数组的特点。
）8-5 编写程序，从键盘输入某班学生C语言课程考试成绩，评定每个学生C语言成绩等级。
如果高于平均分10分，则等级为优秀；如果低于平均分10分，则等级为一般；否则等级为中等。
解：#include "stdio.h"#define N 3void main(){int i ,j;float average,a[N],sum=0;for(i=0;i<N;i++){scanf("%f",&a[i]) ;sum=sum+a[i];}average=sum/N;for(i=0;i<N;i++){if(a[i]>average+10) printf("a[%d]优秀\n",i);else if(a[i]<average-10) p rintf("a[%d]一般\n",i);else printf("a[%d]中等\n",i);}}思考：表示数组元素的a[i]一般称为什么变量？它与一般变量有何区别？8-6 某班期终考试有六门课程，编写程序计算每门课程的平均成绩。
进一步考虑全年级10个班的情况。
解：#include "stdio.h"#define N 30#define M 6void main(){int i,j;float average[M],a[N][M],sum=0;for(i=0;i<N;i++)for(j=0;j<M;j++)scanf("%f",&a[i][j]);for(j=0;j<M;j++){sum=0;for(i=0;i<N;i++)sum=sum+s[i][j] ;average[j]=sum/N;}printf("6门课程的平均成绩分别为：\n");for(i=0;i<M;i++){printf("%f ",average[i]);}printf("\n") ;}思考：在此题中定义的数组a[N][M]中，N表示什么？M 表示什么？若考虑全年级10个班的情况，程序应做哪些改进？8-7 编写程序，将一个一维数组进行逆制。
例如，原来顺序为1，3，5，7，则逆置后的顺序为7，5，3，1.解：#include "stdio.h"#define N 4void fun(int a[]){int i,t ;for(i=0;i<N/2;i++){t=a[i] ;a[i]=a[N-1-i];a[N-1-i]=t;}for(i=0;i<N;i++){printf("%d",a[i]) ;}}void main(){int i ,a[N] ;printf("请输入一维数组各元素的值：\n");for(i=0;i<N;i++)scanf("%d",&a[i]);fun(a);printf("\n");}思考：如果要对7个元素的数组进行逆置操作，只需要修改什么地方？数组的元素的可以是算术表达式吗？有何要求？8-8 编写程序，打印如下的杨辉三角形。
11 11 2 11 3 3 11 4 6 4 1解：#include "stdio.h"#define N 6void main(){int i,j,a[N][N]={1},k;for(i=1;i<N;i++){for(j=1;j<N;j++)if(j==1||i==j) a[i][j]=a[0][0] ;else a[i][j]=a[i-1][j-1]+a[i-1][j] ;}for(i=1;i<N;i++){for(k=1;k<=N-i;k++) /* 每行前面的空格*/printf(" ") ;for(j=1;j<=i;j++)printf("%4d",a[i][j]) ;printf("\n") ;}}思考：在此题中定义一个a[N][N]的方阵数组显然有些浪费（有些元素闲置，却占用存储空间），可否考虑用一维数组进行处理？8-9 编写程序，用筛选法求100-1000之间的素数。
解：#include "stdio.h"#define N 1000void main(){int i,a[N],n=0,db ;for(i=1;i<N;i++)a[i]=1 ;for(i=2;i<N/2;i++){if(a[i]==0) continue ;db=i*2;while(db<N){a[db] =0;db=db+1;}}for(i=100;i<N;i++)if(a[i==1]){printf("%d",i);n++ ;if(n%18==0) printf("\n") ;}printf("\n") ;}思考：在程序实际已求出了什么范围之间的所有素数？在while循环中的“a[db]=0;”语句的作用是什么了？8-10 编写程序，利用数组实现大整数的加减运算。
假定大整数不超过10位数字。
解：#include "stdio.h"#include "string.h"#define N 10int a[N],b[N],c[N],d[N],jw=0;int flag=1 ;/*标志两个大整数的大小关系*/void chag0(int a[],int n)void main(){for(int i=0;i<=n;i++)a[i]=0;}void add() /*求两个大整数的和*/{int i ;for(i=0;i<N;i++){c[i]=(a[i]+b[i]+jw)%10 ;jw=(a[i]+b[i]+jw)/10 ;//计算进位}jw=0 ;printf("两数和为：")；for(i=N-1;i>=0;i--)if(!c[i]&&!jw)continue ;else{printf("%d",c[i]);jw=1 ;}printf("\n") ;}void mus() /*求两个大整数的差*/ {int i ;jw=0;for(i=0;i<N;i++){if(a[i]-jw>=b[i]){d[i]=a[i]-b[i]-jw ;jw=0 ;//表示无借位}else{d[i]=a[i]-b[i]-jw ;jw=1 ;//表示有借位}}jw=0;printf("两数差为：")；if(!flag) printf("-") ;for(i=N-1;i>=0;i--)if(!d[i]&&!jw) continue ;else {printf("%d",d[i]);jw=1;}}void main(){int i,n1,n2;chg0(a,N);chg0(b,N);chg0(c,N);chg0(d,N);chars1[N]，s2[N];printf("请输入加数（减数）：\n") ;scanf("%s",s1) ;printf("请输入被加数（被减数）：\n") ; scanf("%s",s2) ;n=strlen(s1);n=strlen(s2);if(n1>n2||(n1==n2&&strcmp(s1,s2)>=0)) {for(i=0;i<=n1;i++)a[i]=s1[n1-i-1]-48 ;for(i=0;i<=n2;i++)a[i]=s2[n2-i-1]-48 ;}else{for(i=0;i<=n1;i++)b[i]=s1[n1-i-1]-48 ;for(i=0;i<=n2;i++)b[i]=s2[n2-i-1]-48 ;flag=0;}add();mus();printf("\n") ;}思考：此程序中变量的jw的作用什么？他在函数add()与mus()中的作用一样吗？判断式“if(!d[i]&&!jw)”为真时是什么情况？将大整数以字符串的形式进行输入的好处是什么？8-11 编写程序，从键盘输入两个4x4的矩阵A和B，求出它们的和、差、积，并按矩阵的形式输出。