strcpy和strcmp的面试题辩论

strcpy:

   

strcmp:

   

strchr:

   

 

在linux的函数库中这几个函数写法如下：

  strcpy:

        

char *strcpy(char *dest, const char *src)
{
        char *tmp = dest;

        while ((*dest++ = *src++) != '\0')
                /* nothing */;
        return tmp;
}


strcmp:

int strcmp(const char *cs, const char *ct)
{
        signed char __res;

        while (1) {
                if ((__res = *cs - *ct++) != 0 || !*cs++)
                        break;
        }
        return __res;
}


strchr:

char *strchr(const char *s, int c)
{
        for (; *s != (char)c; ++s)
                if (*s == '\0')
                        return NULL;
        return (char *)s;
}


个人建议：在笔试面试中，最好在函数中加个出错判断，如assert(S == NULL )