继承类同时为友元类

　　昨天看到有人在说这个，确实比较有意思。既不违反语法，又比较出乎意料。就像C里面那种switch里嵌套一层do while语句一样。

void cpy(char* to, char* from, size_t count)
{

    register n = (count + 7) / 8;
    switch (count % 8)
    {
        case 0:
        do
        {
            *to = *from++;
        case 7:
            *to = *from++;
        case 6:
            *to = *from++;
        case 5:
            *to = *from++;
        case 4:
            *to = *from++;
        case 3:
            *to = *from++;
        case 2:
            *to = *from++;
        case 1:
            *to = *from++;
        }
        while (--n > 0);
    }
}