[computer-go] C++ pointer question

[Berk Ozbozkurt]

Peter Drake wrote:

> Okay, I've got this method in my BitBoard class:
>
> void dilate() // Expand to include all adjacent points
> {
>     BitBoard temp;
>     temp.bits[0] = bits[0] | (bits[0] << 1) | (bits[0] >> 1) | bits[1];
>     temp.bits[board_width - 1] = bits[board_width - 1] | (bits 
> [board_width - 1] << 1)
>         | (bits[board_width - 1] >> 1) | bits[board_width - 2];
>     for (unsigned row = 1; row < board_width - 1; row++) {
>         temp.bits[row] = bits[row] | (bits[row] << 1) | (bits[row] >> 
> 1) |  bits[row - 1] | bits[row + 1];
>     }
>     for (unsigned row = 0; row < board_width; row++) {
>         bits[row] = temp.bits[row];
>     }
> }
>
> Is there some way to avoid that second for loop? I tried "this =  
> temp" and "*this = *temp", but the compiler isn't happy with either.
>
It has been quite a while since I used C++, but IIRC (and assuming you 
have not overloaded [, ], << and >> operators) you can store your data 
(bits) in a dynamic array. In that case a simple assignment will work:

class Bitboard{
    bits_type *bits;
    Bitboard()
    {
            bits=new bits_type[ARRAY_SIZE];
           ....
     }
    ~Bitboard()
    {
            delete[] bits;
           ....
     }
void dilate() // Expand to include all adjacent points
{
    bits_type *temp=new bits_type[ARRAY_SIZE];
    temp.bits[0] = bits[0] | (bits[0] << 1) | (bits[0] >> 1) | bits[1];
...
    delete[] bits;
    bits=temp;
   }
}

}