Software Design Engineer Questions[评：知名公司笔试]

[stars_625]

1．Write a function that would: sort an integer array in increasing order.

//example: “3 2 5” => “2 3 5”

void sort(int *a, int len)
{
    int i;
    int *tmp;

    for(len--; len>0; len--)
    {
        for(i=0; i<len; i++)
        {
            if(*(a+i)>*(a+i+1))
            {
                *tmp = *(a+i);
                *(a+i) = *(a+i+1);
                *(a+i+1) = *tmp;
            }
        }
    }
}

冒泡排序

2．Write a function that would: remove extra spaces in a string without using buffer. (i.e. only keep one space for multiple contiguous spaces)

//example: “a b c” => “a b c”

void m_remove(char *s)
{
    char *tmp;
    char *spaces = "  ";
    
    tmp = strstr(s, spaces);
    while(tmp)
    {
        strcpy(tmp,tmp+1);
        tmp = strstr(s, spaces);
    }
}

char strstr(const char *s1,const char *s2)
扫描字符串s2,并返回第一次出现s1的位置

char strcpy(char *dest,const char *src)
将字符串src复制到dest

3．Write a function that would: return the number of ones for an integer when it is written in binary format

//example: if a is 5 (101), return 2; if a is 8 (1000), return 1

int count(int a)
{
    int len = 0;
    int one_num = 0;
    
    len = sizeof(a);                /* 求出int字节数，提高系统兼容性 */
    len = len << 3;                 /* 乘八，占用二进制位数 */

    while(len--)
    {
        if(a & 0x01)one_num++;      /* 判a的第0位是否为1 */
        a >>= 1;                    /* a左移一位 */
    }
    return one_num;
}
/* 总体思想是将整形转换成二位制，进行位判断 */