public class Grid15
{
    int [][]m_board;
    Grid15()
    {
        m_board=new int[3][3];
    }//Grid15构造方法
   
    //棋盘格线
    private void mb_outputGridRowBoard()
    {
        int i;
        System.out.print("+");
        for(i=0;i<5;i++)
            System.out.print("-");
        System.out.println("+");
    }
   
    //数据
    private void mb_outputGridRowBoard(int i)
    {
        int j;
        for(j=0;j<m_board[i].length;j++)
            System.out.print("|"+m_board[i][j]);
        System.out.println("|");
    }
   
    //棋盘
    public void mb_outputGrid()
    {
        int i;
        mb_outputGridRowBoard();
        for(i=0;i<m_board.length;i++)
        {
            mb_outputGridRowBoard(i);
            mb_outputGridRowBoard();
        }
    }
   
    //初始化数据
    private void mb_dataInit()
    {
        int i,j,k;
        for(i=0,k=1;i<m_board.length;i++)
            for(j=0;j<m_board[i].length;j++,k++)
                m_board[i][j]=k;
    }
//以下略过。。。
......
......
......
m_board.length和m_board[i].length的长度不同吗？是怎么算的啊？

如果我想在c++里表示这个长度该怎么改？还是直接用数字？

求解惑！谢谢大神们！

public class LengthTest {

    public static void main(final String[] args) {
        int[][] m_board = new int[3][3];
        System.out.println("m_board.length:" + m_board.length);
        for (int i = 0; i < 3; i++) {
            System.out.println("m_board[i].length:" + m_board[i].length);
        }
    }
}

执行结果：
m_board.length:3
m_board[i].length:3
m_board[i].length:3
m_board[i].length:3

public class LengthTest {

    private final static int ROW = 2;
    private final static int COL = 3;

    public static void main(final String[] args) {
        int[][] m_board = new int[ROW][COL];
        System.out.println("m_board.length:" + m_board.length);
        System.out.println("m_board[i].length:" + m_board[0].length);
    }
}

执行结果：
m_board.length:2
m_board[i].length:3

或许这个例子能更好的说明问题