c50

//50.使用c语言编写函数：unsigned int reverse_bit(unsigned int value);//这个函数的返回值是value的二进制位模式从左到右翻转后的值/*方法一：通过位运算取出25的每一位二进制数，取出第一个数乘以2^31,第二个数乘以2^30，依次取出并计算出总和#include <stdio.h>#include <math.h>#include <stdlib.h>typedef unsigned int unit;int main(){unit reverse_bit(unit value);int value=0;int num=0;scanf("%d",&value);num=reverse_bit(value);printf("%u\n",num);return 0;}unit reverse_bit(unit value){int i=0;unit num=0;for(i=0;i<32;i++){num+=((value>>i)&1)*pow(2,31-i);}return num;}*//*方法二：通过位运算直接将取出的第一位左移31位，第二位左移30位，设置一个变量进行移位运算，经过循环每一位都进行左移#include <stdio.h>int main(){unsigned int reverse_bit(unsigned int value);int value=0;int num=0;scanf("%d",&value);num=reverse_bit(value);printf("%u\n",num);return 0;}unsigned int reverse_bit(unsigned int value){unsigned int ret=0;int i=0;while(i<32){ret<<=1;ret|=(value>>i)&1;i++;}return ret;}*//*49.有一个字符串是"student a am i",现编写代码将字符串转换为"i am a student" 要求：空间复杂度是O(1)//可以先将整个字符串逆序"i ma a tneduts"//再将每个单词逆序"i am a student"#include <stdio.h>#include <stdlib.h>#include <assert.h>#include <string.h>int main(){void reverse_str(char *left,char *right);void reverse(char *str);char str[]="strudent a am i";reverse(str);printf("%s\n",str);return 0;}void reverse_str(char *left,char *right){assert(left);assert(right);while(left<right){char tmp =*left;*left=*right;*right=tmp;left++;right--;}}void reverse(char *str){char *pstart=str;char *pend=str+strlen(str)-1;char *pcur=NULL;if((str==NULL)||(*str=='\0')){return;}reverse_str(pstart,pend);while(*str){pcur=str;while(*str!='\0'&&*str!=' '){str++;}pend=str-1;reverse_str(pcur,pend);if(*str==' ')str++;}}*//*48.实现一个函数可以求任意多个整数的平均值(使用可变参数列表)#include <stdio.h>#include <stdarg.h>float averge(int val,...){va_list arg;int count;float sum=0.0;va_start(arg,val);for(count=0;count<val;count++){sum+=va_arg(arg,int);}va_end(arg);return  sum/ val;}int main(){float ret=averge(5,1,2,3,4,5);printf("%f\n",ret);return 0;}*//*47.1元钱一瓶汽水，喝完后两个空瓶换一瓶汽水，问：你有20元钱，最多可以喝到几瓶汽水？#include <stdio.h>int main(){int money=9;int count=money;while(1){if(money%2!=0){count=count+money;break;}else{money=money/2;count+=money;}}printf("%d\n",count);return 0;}*//*46.将一个数字字符串转换为对应的数字，不考虑溢出。（比如"12.34"转换为数字：12.34）功能类似atof，考虑异常输入#include <stdio.h>#include <stdlib.h>#include <math.h>#include <ctype.h>int main(){double my_atof(char *str);double ret;char arr[100];scanf("%s",arr);ret=my_atof(arr);printf("%f\n",ret);return 0;}double my_atof(char *str){double ret=0.0;int sign=1;char *point;while(*str!='\0'){if(isspace(*str)){str++;}else if(*str=='-'){sign=-1;str++;}else if((*str=='+')){str++;}else if(*str=='.'){point=str;str++;}else if((*str>='0')&&(*str<='9')){ret=ret*10.0+(*str-'0');str++;}}ret=sign*ret/pow(10,str-point-1);return ret;}*//*45.(memset)实现内存的设置，功能类似memset，可以以字节为单位设置内存的值，不能使用任何库函数#include <stdio.h>#include <assert.h>int main(){void *my_memset(void *s,int ch,int n);char s1[10];int i=0;my_memset(s1,7,7);for(i=0;i<10;i++){printf("%d ",s1[i]);}printf("\n");return 0;}void *my_memset(void *s,int ch,int n){assert(s);char *dst=(char*)s;int i=0;for(i=0;i<n;i++){*(dst+i)=ch;}return s;}*//*44.(memmove)实现内存的移动，功能类似memmove，实现内存重叠拷贝，不能使用任何库函数//memmove://(1)当源内存的首地址等于目标内存的首地址时，不进行任何拷贝；//(2)当源内存的首地址大于目标内存的首地址时，实行正向拷贝;//(3)当源内存的首地址小于目标内存的首地址时，实行反向拷贝;#include <stdio.h>#include <assert.h>int main(){void *my_memmove(void *dst,const void *src,int count);char p[]="hello-world";char q[10];my_memmove(p+1,p,6);printf("%s\n",p);my_memmove(q,p,6);printf("%s\n",q);return 0;}void *my_memmove(void *dst,const void *src,int n){void *ret=dst;char *p1=(char*)dst;char *p2=(char*)src;assert(dst);assert(src);if((p2<=p1)&&(p1<=p2+n)){p2=p2+n-1;p1=p1+n-1;while(n--){*p1=*p2;p1--;p2--;}}else{while(n--){*p1=*p2;p1++;p2++;}*p1='\0';}return ret;}*//*43.(memcpy)实现内存的拷贝，功能类似memcpy，可以不实现内存重叠拷贝，不能使用任何库函数#include <stdio.h>#include <assert.h>int main(){void *my_memcpy(void *dst,const void *src,int n);char a[]="hello world";char b[10];my_memcpy(b,a,7);printf("%s\n",b);return 0;}void *my_memcpy(void *dst,const void *src,int n){void *ret=dst;char *p1=(char*)dst;char *p2=(char*)src;assert(dst);assert(src);while(n--){*p1++=*p2++;}*p1='\0';return ret;}*//*memcmp#include <stdio.h>#include <assert.h>int main(){int my_memcmp(const void *dst,const void *src,int count);int a[10]={1,2,3,4,5,6,7,8,9,0};int b[]={1,1,3};int ret=my_memcmp(a,b,5);printf("%d\n",ret);return 0;}int my_memcmp(const void *dst,const void *src,int count){assert(dst);assert(src);while(*(char*)dst==*(char*)src){dst=(char*)dst+1;src=(char*)src+1;count--;if(count==0){return 0;}}if(*(char*)dst>*(char*)src){return 1;}else{return -1;}}*//*42.(strcmp)实现字符串的比较，功能类似strcmp，不能使用任何库函数#include <stdio.h>int main(){int my_strcmp(const char *dest,const char *src);char s1[50],s2[50];printf("input s1:");scanf("%s",s1);printf("input s2:");scanf("%s",s2);int ret=my_strcmp(s1,s2);printf("%d\n",ret);return 0;}int my_strcmp(const char *str1,const char *str2){int i=0,j=0;int result;while((str1[i]==str2[j])&&(str1[i]!='\0')){i++;j++;}if(str1[i]=='\0'&&str2[j]=='\0'){result=0;}else{result=str1[i]-str2[j];}return result;}*//*41.(strcat)实现字符串的连接，功能类似strcat，不能使用任何库函数#include <stdio.h>int main(){char *my_strcat(char *dest,const char *src);char s1[50],s2[50];printf("input s1:");scanf("%s",s1);printf("input s2:");scanf("%s",s2);my_strcat(s1,s2);printf("s1:%s\n",s1);return 0;}char *my_strcat(char *dest,const char *src){int i=0,j=0;char *t=dest;while(dest[i]!='\0'){i++;}while(src[j]!='\0'){dest[i++]=src[j++];}dest[i]='\0';return t;}*//*40.(strcpy)实现字符串的拷贝，功能类似strcpy，不能使用任何库函数#include <stdio.h>#include <assert.h>int main(){char *my_strcpy(char *dest,const char *src);char s1[50],s2[50];printf("input s2:");scanf("%s",s2);my_strcpy(s1,s2);printf("s1:%s\n",s1);return 0;}char *my_strcpy(char *dest,const char *src){assert(dest);assert(src);char *t=dest;while((*dest++=*src++)!='\0'){}return t;}*/