C++ - Chess Bishop MoveCode Error?

Question

So i'm making a chess game, however i can't get the bishop piece moving correctly.

This is my chessboard:

string board[8][8] = {

{"_" , "_", "_" , "_" ,"_", "_" , "_" , "_"},
{"_" , "_", "_" , "_" ,"_", "_" , "_" , "_"},
{"_" , "_", "_" , "_" ,"_", "B" , "_" , "_"},
{"_" , "_", "_" , "_" ,"_", "_" , "_" , "_"},
{"_" , "_", "_" , "_" ,"_", "_" , "_" , "_"},
{"_" , "_", "_" , "_" ,"_", "_" , "_" , "_"},
{"_" , "_", "_" , "_" ,"_", "_" , "_" , "_"},
{"_" , "_", "_" , "_" ,"_", "_" , "_" , "_"} };

Here is the Draw function to draw board.

void Draw()
{
for( int i = 0; i < 8; i++ )
{
    for( int j = 0; j < 8; j++ )
        std::cout << board[ i ][ j ] << ' ';

    std::cout << '\n';
}
cout<<"\n";
}

Bishop Movement Code so far.

 if (board[x][y] == "B")
 {      //Highlight the users chosen piece
     board[x][y] = "\033[0;31mB\033[0m";
     //Now showing available moves the chosen bishop can move to
     for(int counter=1; counter <=7; counter++) {
         if(board[x+counter][y+counter] == "_") {  //if there is an empty space, then place X to show peice can move there
             board[x+counter][y+counter] = "X";
         }
         else {  //if cannot move their ,then break
             break;
         }
     }
}

Here is my problem. It shows the X spaces the piece is able to move to to the user in some places on the board. however when the piece is in certain places of the array like the the place it is in the board code. It overlaps and shows Xs on different side of the board, instead of stopping drawing the Xs when their is no "_" available.

Answer 1

You need to check if x + counter and y + counter fall within the board.

if (board[x][y] == "B")
{      //Highlight the users chosen piece
    board[x][y] = "\033[0;31mB\033[0m";
    //Now showing available moves the chosen bishop can move to
    for(int counter = 1; (x + counter) <= 7 && (y + counter) <= 7; counter++){
        if(board[x + counter][y + counter] == "_") {  
            //if there is an empty space, then place X to show peice can move there
            board[x + counter][y + counter] = "X";
        }
        else {   //if cannot move their ,then break
            break;
        }
    }
}

Of course, this marks only one direction, while the bishop can actually move in four directions.

Also, this does not check if there are any pieces in between the path.

To consider all four directions, you can create a direction matrix, which stores the change in x and y for each of the directions.

// 4 directions in which bishop can move
int dx[4] = {-1, -1, 1, 1};
int dy[4] = {-1, 1, -1, 1};


if (board[x][y] == "B")
{
    // for each direction
    for(int dir = 0; dir < 4; dir++) {

        // the bishop can move to a maximum of 7 squares
        for(int counter = 1; counter < 8; counter++) {

            // calculate where the bishop will be 
            // after moving "counter" number of squares
            int new_x, new_y;
            new_x = x + dx[dir] * counter;
            new_y = y + dy[dir] * counter;

            // check if the square lies within the board
            if(new_x >= 0 && new_x < 8 && new_y >= 0 && new_y < 8) {

                // if there is an empty space, then place X to show peice can move there
                if(board[cur_x][cur_y] == "_") {  
                    board[cur_x][cur_y] = "X";
                }

                // if there is any other piece in between, the bishop can't move further
                else {
                    break;
                }
            }

            // break if the square is outside the board
            else {
                break;
            }
        }
    }
}