嵌入式工程师笔试题一

1、将一个字符串逆序 

 

#include<stdio.h>
#include<string.h>
#include<malloc.h>


char *mystrrev(char *const dest,const char *const src)
{
    if( dest==NULL && src==NULL )
        return NULL;

    int val_len = strlen(src);

    dest[val_len] = '';
    int i;
    for( i=0; i<val_len; i++ ){
    *(dest+i) = *(src+val_len-1-i);
    }
    return dest;

}
int main( )
{
    char *str="asdfa";
    char *str1=NULL;
    str1 = (char *)malloc(20);
    if( str1 == NULL )
    {
        printf("molloc failed!
");
    }
    printf("%s
", mystrrev(str1,str));
    free(str1);
    str1=NULL;
    return 0;
}

 

2、将一个链表逆序 

 

#include<stdio.h>
#include<malloc.h>

typedef struct List{
    int data;
    struct List *next;
}List;

List *list_create( void )
{
    List *head,*tail,*p;
    int e;
    head = (List *)malloc(sizeof(List));
    tail = head;
    printf("
List Create,input number(end of 0):");
    scanf("%d",&e);
    while( e )
    {
        p = (List *)malloc(sizeof(List));
        p->data = e;
        tail->next = p;
        tail = p;
        scanf("%d",&e);
    }
    tail->next=NULL;
    return head;
}

List *list_reverse(List *head)
{
    List *p,*q,*r;
    p = head;
    q = p->next;
    while(q!=NULL)
    {
        r=q->next;
        q->next=p;
        p=q;
        q=r;
    }
    head->next = NULL;
    head = p;

    return head;
}

void main( )
{
    List *head,*p;
    int d;
    head = list_create( );
    printf("
");
    for( p=head->next; p; p=p->next )
    {
        printf("--%d--",p->data);
    }
    head = list_reverse(head);
    printf("
");
    for( p=head; p->next; p=p->next )
        printf("--%d--",p->data);

}

 

3、计算一个字节里（byte）里面有多少bit被置1 

 

#include<stdio.h>

#define N 10
#ifndef BYTE
typedef unsigned char BYTE;
#endif

int comb(BYTE b[ ],int n)
{
    int count=0;
    int bi,bj;
    BYTE cc=1,tt;

    for( bi=0; bi<n; bi++ )
    {
        tt=b[bi];
        for( bj=0; bj<8; bj++ )
        {
            if( (tt&cc) == 1 )
            {
                count++;
            }
            tt = tt/2;
        }
    }
    return count;
}

int main( )
{
    BYTE b[10] = {3,3,3,11,1,1,1,1,1,1};
    printf("%d
",comb(b,N));
    return 0;
}

 

4、在一个字符串中找到可能的最长的子字符串，

该函数在一个字符串中找到可能的最长的子字符串，且该字符串是由同一字符组成的。

 

#include<stdio.h>
#include<stdlib.h>
#include<string.h>

char * search( char *cpsource, char ch )
{
    char *cpTemp=NULL,*cpDest=NULL;
    int iTemp,iCount=0;
    while( *cpsource )
    {
        if( *cpsource == ch )
        {
            iTemp = 0;
            cpTemp = cpsource;
            while( *cpsource == ch )
            {
                ++iTemp;
                ++cpsource;
            }
            if( iTemp > iCount )
            {
                iCount = iTemp;
                cpDest = cpTemp;
            }
            if( !*cpsource )
                break;
        }
        ++cpsource;
    }
    return cpDest;
}

int main( )
{
    char s[200];
    char ch;
    printf("请输入您要处理的字符串:
");
    while( gets(s) )
    {
          printf("请输入匹配字符：
");

          scanf("%c",&ch);
          getchar( );
          printf("%c
",ch);
          printf("%s
",search(s,ch));
          printf("请输入您要处理的字符串:
");
    }
    return 0;
}

 

5、整数转换为字符串

 

#include<stdio.h>
#include<string.h>

void reverse( char s[ ] )
{
    char c;
    int i=0;
    int j;
    for( j=strlen(s)-1; i<j; j-- )
    {
        c = s[i];
        s[i] = s[j];
        s[j] = c;
        i++;
    }
}

void IntegerToString( char s[ ],int n )
{
    int i=0;
    int sign;
    if( (sign=n)<0 )
        n=-n;
    do
    {
        s[i++] = n%10+'0';
    }while( (n=n/10)>0 );
    if( sign < 0 )
        s[i++] = '-';
    s[i] = '';
    reverse(s);
}
int main( )
{
    int m;
    char c[100];
    printf("请输入整数m:");
    scanf("%d",&m);
    IntegerToString(c,m);
    printf("integer = %d string = %s
",m,c);
}

 6、字符串转换为整数 

#include<stdio.h>
#include<string.h>

int MyAtoI( char str[] )
{
    int i;
    int weight = 1;
    int rtn = 0;

    for( i=strlen(str)-1; i>=0; i-- )
    {
        rtn += (str[i]-'0')*weight;
        weight *= 10;
    }
    return rtn;
}

void main( )
{
    char str[32];

    printf("Input a string:");
    gets(str);
    printf("%d
",MyAtoI(str));
}