实现字符串中寻找字串

const char * my_strstr(const char *src, const char *sub)
{
    const char *bp;
    const char *sp;
    //入口参数检查
    assert((src != NULL) && (sub != NULL));
    //判断src与sub的有效性
    while (*src)
    {
        bp = src;  //用于src的遍历
        sp = sub;  //用于sub的遍历
        //每次src+1，然后与sub依次比较
        while (*bp++ == *sp++)
        {
            if (!*sp)
            {
                //找到了
                return src;
            }
        }
        src++;
    }
    return NULL;
}


int main()
{
    char p[] = "12345";
    char q[] = "34";

    char *r = my_strstr(p, q);
    printf("r:%s\n",r);

    return 0;
}