memmove()

memcpy()只是memmove()的一个子集

memcpy()在执行内存重叠的情况下时，就会发生错误，而memmove()不会

void *memmove(void *dest, const void *src, size_t count){    assert((dest!=0)&&(src!=0));    unsigned char *pdest =(char * )dest;    unsigned char *psrc = (char * )src;    int i=0;    if ((pdest < psrc) || (pdest > psrc + count)) ///正向拷贝    {        for (i= 0; i < count; i++)         {　　        *pdest ++ = *psrc ++;        }    }    else      /*反向拷贝*/    {       psrc += count;       pdest += count;        for (i= 0; i < count; i++)       {           psrc --;           pdest --;           *pdest = *psrc;       }     }    return dest;}