c语言-C程序设计(第四版)谭浩强_课后习题答案第8章.doc

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1、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

2、.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 int main() void swap

3、(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(n1n2) swap(p1,p2); if(n1n3) swap(p1,p3); if(n2n3) swap(p2,p3); printf(Now,the order is:%d,%d,%dn,n1,n2,n3); return 0; void swap(int *p1,int *p2) int p; p=*

4、p1; *p1=*p2; *p2=p; #include #include int main()void swap(char *,char *); char str120,str220,str320; 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

5、order is:n); printf(%sn%sn%sn,str1,str2,str3); return 0; void swap(char *p1,char *p2) char p20; strcpy(p,p1);strcpy(p1,p2);strcpy(p2,p); 8-3#include int main() void input(int *); void max_min_value(int *); void output(int *); int number10; input(number); max_min_value(number); output(number); return

6、 0; void input(int *number) int i; printf(input 10 numbers:); for (i=0;i10;i+) scanf(%d,&numberi); void max_min_value(int *number) int *max,*min,*p,temp; max=min=number; for (p=number+1;p*max) max=p; else if (*p*min) min=p; temp=number0;number0=*min;*min=temp; if(max=number) max=min; temp=number9;nu

7、mber9=*max;*max=temp; void output(int *number) int *p; printf(Now,they are: ); for (p=number;pnumber+10;p+) printf(%d ,*p); printf(n); 8-4#include int main() void move(int 20,int,int); int number20,n,m,i; printf(how many numbers?); scanf(%d,&n); printf(input %d numbers:n,n); for (i=0;in;i+) scanf(%d

8、,&numberi); printf(how many place you want move?); scanf(%d,&m); move(number,n,m); printf(Now,they are:n); for (i=0;iarray;p-) *p=*(p-1); *array=array_end; m-; if (m0) move(array,n,m); 8-5#include int main()int i,k,m,n,num50,*p; printf(ninput number of person: n=); scanf(%d,&n); p=num; for (i=0;in;i

9、+) *(p+i)=i+1; i=0; k=0; m=0; while (mn-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.%dn,*p); return 0;8-6#include int main()int length(char *p);int len;char str20;printf(input string: );scanf(%s,str);len=length(str);printf(The length

10、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 #include int main()void copystr(char *,char *,int); int m; char str120,str220; printf(input string:); gets(str1); printf(which character that begin to copy?); scanf(%d,&m); if (strlen(str1)m)

11、printf(input error!); else copystr(str1,str2,m); printf(result:%sn,str2); return 0;void copystr(char *p1,char *p2,int m) int n; n=0; while (nm-1) n+; p1+; while (*p1!=0) *p2=*p1; p1+; p2+; *p2=0;8-8#include int main()int upper=0,lower=0,digit=0,space=0,other=0,i=0;char *p,s20;printf(input string: );

12、while (si=getchar()!=n) i+;p=&s0;while (*p!=n) if (A=*p) & (*p=Z) +upper; else if (a=*p) & (*p=z) +lower; else if (*p= ) +space; else if (*p=0) +digit; else +other; p+; printf(upper case:%d lower case:%d,upper,lower);printf( space:%d digit:%d other:%dn,space,digit,other);return 0;8-9#include int mai

13、n()void move(int *pointer); int a33,*p,i; printf(input matrix:n); for (i=0;i3;i+) scanf(%d %d %d,&ai0,&ai1,&ai2); p=&a00; move(p); printf(Now,matrix:n); for (i=0;i3;i+) printf(%d %d %dn,ai0,ai1,ai2); return 0; void move(int *pointer) int i,j,t; for (i=0;i3;i+) for (j=i;j3;j+) t=*(pointer+3*i+j); *(p

14、ointer+3*i+j)=*(pointer+3*j+i); *(pointer+3*j+i)=t; 8-10-1#include int main()void change(int *p); int a55,*p,i,j; printf(input matrix:n); for (i=0;i5;i+) for (j=0;j5;j+) scanf(%d,&aij); p=&a00; change(p); printf(Now,matrix:n); for (i=0;i5;i+) for (j=0;j5;j+) printf(%d ,aij); printf(n); return 0;void

15、 change(int *p) int i,j,temp; int *pmax,*pmin; pmax=p; pmin=p; for (i=0;i5;i+) for (j=i;j5;j+) if (*pmax*(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;i5;i+) for (j=0;j*(p+5*i+j) pmin=p+5*i+j; temp=*pmin; *pmin=*(p+4); *(p+4)=temp;

16、 pmin=p+1; for (i=0;i5;i+) for (j=0;j*(p+5*i+j)pmin=p+5*i+j; temp=*pmin; *pmin=*(p+20); *(p+20)=temp; pmin=p+1; for (i=0;i5;i+) for (j=0;j*(p+5*i+j) pmin=p+5*i+j; temp=*pmin; *pmin=*(p+24); *(p+24)=temp; 8-10-2#include int main()void change(int *p); int a55,*p,i,j; printf(input matrix:n); for (i=0;i

17、5;i+) for (j=0;j5;j+) scanf(%d,&aij); p=&a00; change(p); printf(Now,matrix:n); for (i=0;i5;i+) for (j=0;j5;j+) printf(%d ,aij); 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;i5;i+) /找最大值和最小值的地址,并赋给 pmax,pmin for (j=i;j5;j+) if (*pmax*(p+5*i+j)

18、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a01的地址赋给pmin，从该位置开始找最小的元素 for (i=0;i5;i+) /找第二最小值的地址赋给 pmin for (j=0;j *(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;i5;i+

19、) /找第三最小值的地址赋给pmin for (j=0;j*(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;i5;i+) / 找第四最小值的地址赋给pmin for (j=0;j*(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 #include int main()void sort(char s6)

20、; int i; char str106; printf(input 10 strings:n); for (i=0;i10;i+) scanf(%s,stri); sort(str); printf(Now,the sequence is:n); for (i=0;i10;i+) printf(%sn,stri); return 0;void sort(char s106)int i,j; char *p,temp10; p=temp; for (i=0;i9;i+) for (j=0;j0) strcpy(p,sj); strcpy(sj,s+j+1); strcpy(sj+1,p); 8

21、-11-2#include #include int main()void sort(char (*p)6); int i; char str106; char (*p)6; printf(input 10 strings:n); for (i=0;i10;i+) scanf(%s,stri); p=str; sort(p); printf(Now,the sequence is:n); for (i=0;i10;i+) printf(%sn,stri); return 0; void sort(char (*s)6)int i,j; char temp6,*t=temp; for (i=0;

22、i9;i+) for (j=0;j0) strcpy(t,sj); strcpy(sj,s+j+1); strcpy(sj+1,t); 8-12#include #include int main()void sort(char *); int i; char *p10,str1020; for (i=0;i10;i+) pi=stri; printf(input 10 strings:n); for (i=0;i10;i+) scanf(%s,pi); sort(p); printf(Now,the sequence is:n); for (i=0;i10;i+) printf(%sn,pi

23、); return 0; void sort(char *s)int i,j; char *temp; for (i=0;i9;i+) for (j=0;j0) temp=*(s+j); *(s+j)=*(s+j+1); *(s+j+1)=temp; 8-13#include#includeint 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

24、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:%fn,c);p=fcos;c=integral(p,a2,b2,n);printf(The integral

25、of cos(x) is:%fn,c);p=fexp;c=integral(p,a3,b3,n);printf(The integral of exp(x) is:%fn,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) ret

26、urn cos(x); float fexp(float x) return exp(x);8-14#include int main()void sort (char *p,int m); int i,n; char *p,num20; printf(input n:); scanf(%d,&n); printf(please input these numbers:n); for (i=0;in;i+) scanf(%d,&numi); p=&num0; sort(p,n); printf(Now,the sequence is:n); for (i=0;in;i+) printf(%d

27、,numi);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;im/2;i+) p1=p+i; p2=p+(m-1-i); temp=*p1; *p1=*p2; *p2=temp; 8-15#include int main()void avsco(float *,float *); void avcour1(char (*)10,float *); void fali2(char course510,int num,float *pscore,float

28、 aver4); void good(char course510,int num4,float *pscore,float aver4); int i,j,*pnum,num4; float score45,aver4,*pscore,*paver; char course510,(*pcourse)10; printf(input course:n); pcourse=course; for (i=0;i5;i+) scanf(%s,coursei); printf(input NO. and scores:n); printf(NO.); for (i=0;i5;i+) printf(,

29、%s,coursei); printf(n); pscore=&score00; pnum=&num0; for (i=0;i4;i+) scanf(%d,pnum+i); for (j=0;j5;j+) scanf(%f,pscore+5*i+j); paver=&aver0; printf(nn); 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(nn); fali2(pcourse,pnum,pscore,paver); / 找出2门课不及格的学生 printf(nn); g

30、ood(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;i4;i+) sum=0.0; for (j=0;j5;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 *psco

31、re) / 求第一课程的平均成绩的函数 int i; float sum,average1; sum=0.0; for (i=0;i4;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:%7.2fn,*pcourse,average1);void fali2(char course510,int num,float *pscore,float aver4) / 找两门以上课程不及格的学生的函数 int i,j,k,labe1; printf( =Stud

32、ent who is fail in two courses= n); printf(NO. ); for (i=0;i5;i+) printf(%11s,coursei); printf( averagen); for (i=0;i4;i+) labe1=0; for (j=0;j5;j+) if (*(pscore+5*i+j)=2) printf(%d,numi); for (k=0;k5;k+) printf(%11.2f,*(pscore+5*i+k); printf(%11.2fn,averi); void good(char course510,int num4,float *p

33、score,float aver4) / 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;i5;i+) printf(%11s,coursei); printf( averagen); for (i=0;i4;i+) n=0; for (j=0;j85.0) n+; if (n=5)|(averi=90) printf(%d,numi); for (k=0;k5;k+) printf(%11.2f,*(pscore+5*i+k); p

34、rintf(%11.2fn,averi); 8-16#include int main() char str50,*pstr; int i,j,k,m,e10,digit,ndigit,a10,*pa; printf(input a string:n); gets(str); pstr=&str0; /*字符指针pstr置于数组str 首地址*/ pa=&a0; /*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+;