C++常考面试题：实现内存拷贝函数

void* memcpy(void *dst,const void *src,size_t count){    assert(dst!=NULL);    assert(src!=NULL);    unsigned char *pdst=(unsigned char*)dst;    const unsigned char *psrc=(const unsigned char *)src;    assert(!(psrc<=psdt)&&pdst<(psrc+count));    assert(!(psrc<=psrc)&&psrc<(pdst+count));    while(count--)    {        *pdst=*psrc;        pdst++;        psrc++;    }    return dst;    }