嵌入式软件工程师面试题

转自 http://www.cnblogs.com/lzjsky/archive/2011/01/15/1936404.html

1、将一个链表逆序

LinkList *reverse(LinkList *head) {   LinkList *p1,*p2 = NULL,*p3 = NULL;   if(head == NULL || head->next == NULL)     return head;   p1 = head->next;   while(p1!=NULL)   {     p3 = p1->next;     p1->next = p2;     p2 = p1;     p1 = p3;  }  head->next = p2;   // head = p2;   return head; }

2、计算一个字节里（byte）里面有多少bit被置1 

#include <</span>stdio.h> int comb(const int c) { int count = 0; int i = 0; int cc = c; while(i++<</span>8) {     if((cc&1)==1)     {         count++;     }     cc = cc>>1; } return count; } int main() { const int c = 0xcf; printf("%d\n",comb(c)); return 1; }

3、在一个字符串中找到可能的最长的子字符串

#include <</span>stdio.h> #include <</span>stdlib.h> #include <</span>string.h> char *commanstring(char shortstring[],char longstring[]) {   int i,j;   char *substring = malloc(256);   if(strstr(longstring,shortstring)!=NULL)     return shortstring;   for(i=strlen(shortstring)-1;i>0;i--)   {     for(j=0;j<</span>=strlen(shortstring)-i;j++)     {       memcpy(substring,&shortstring[j],i);     substring[i]='\0';     if(strstr(longstring,substring)!=NULL)       return substring;     }   }   return NULL; } void main(void) {   char *str1 = "aocdfe";   char *str2 = "pmcdfa";   char *comman = NULL;   if(strlen(str1)>strlen(str2))     comman= commanstring(str2,str1);   else     comman = commanstring(str1,str2);   printf("the longest comman string is:%s\n",comman);     }

4、字符串转换为整数 

#include <</span>stdio.h> #include <</span>string.h> void reverse(char s[]) { //字符串反转     int c, i=0, j;     for(j=strlen(s)-1;i<</span>j;j--)     { c=s[i];         s[i]=s[j];         s[j]=c;         i++;     } } void IntegerToString(char s[],int n) { int i=0,sign;     if((sign=n)<</span>0)//如果是负数，先转成正数         n=-n;     do //从个位开始变成字符,直到最高位,最后应该反转     { s[i++]=n%10+'0';     }while((n=n/10)>0);     //如果是负数，补上负号     if(sign<</span>0)         s[i++]='-';     s[i]='\0';//字符串结束     reverse(s); } void main() { int m;     char c[100];     m =215;     IntegerToString(c,m);     printf("integer = %d string = %s\n", m, c); }

5、整数转换为字符串

#include <</span>stdio.h> #include <</span>string.h> int Atoi(char str[]) { int i; int weight = 1; // 权重 int rtn = 0; // 用作返回 for(i = strlen(str) - 1; i >= 0; i--) {    rtn += (str[i] - '0')* weight; //    weight *= 10; // 增重 } return rtn; } void main() { char str[32]; printf("Input a string :"); gets(str); printf("%d\n", Atoi(str)); }

6、将一个字符串逆序

 

#include <</span>stdio.h> #include <</span>string.h> char *strconv(char *p) {     int length = strlen(p); char *ptr = p; char *ptr_1 = p + length -1; while(ptr <</span> ptr_1) { char c = *ptr; *ptr = *ptr_1; *ptr_1 = c; ++ptr; --ptr_1; } return p; } int main() { char str[]="abcdef1234"; char *p; p = strconv(str); printf("%s",p); return 1; }