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  1. #1
    Jonotron is offline Member
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    Default [SOLVED] Explanation of Nested Loop (very strange)

    Hey, I've been programming for a long time, but I'm new to java (I know it's still very similar to others). I'm having a strange result from a board(like chess) I'm making:

    Here is the variable init.
    Java Code:
        //Board Dimensions
        public static final int WIDTH = 20;
        public static final int HEIGHT = 10;
        
        //I'm using boolean because it's either a dot or an asterisk... 
        public static boolean[][] board = new boolean[WIDTH][HEIGHT];

    When I drew the board, the x and y flipped positions for some reason.
    Originally I had this code:
    Java Code:
    static void drawBoard()
        {
          for (int x = 0; x < WIDTH; x++)
          {
              for (int y = 0; y < HEIGHT; y++)
              {
                  if (board[x][y] == true)
                  {
                      System.out.print( '*' );
                  }
                  else
                  {
                      System.out.print( '.' );
                  }   
              }
              System.out.println();
          }
        }
    I was able to correct the problem by just reversing it like this:
    Java Code:
    static void drawBoard()
        {
            //HAVE TO START WITH COLUMN AND INVERSE THE X Y
          for (int x = 0; x < HEIGHT; x++)
          {
              for (int y = 0; y < WIDTH; y++)
              {
                  if (board[y][x] == true) //NEED TO INVERT X AND Y TO MAKE WORK
                  {
                      System.out.print( '*' );
                  }
                  else
                  {
                      System.out.print( '.' );
                  }   
              }
              System.out.println();
          }
        }
    And the desired output should be similar to "Conway's Game of Life" as this is supposed to be a replica.
    Last edited by Jonotron; 11-25-2009 at 02:36 AM. Reason: Solved

  2. #2
    collin389 is offline Senior Member
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    Hello, in your first for loop, you print the heights and then make a new line, and then print the next column, I think what you want to do is print the entire width then make a newline, and then print the next widths. Like this:
    Java Code:
     static void drawBoard()
        {
          for (int y = 0; y < HEIGHT; y++)
          {
              for (int x = 0; x < WIDTH; x++)
              {
                  if (board[x][y] == true)
                  {
                      System.out.print( '*' );
                  }
                  else
                  {
                      System.out.print( '.' );
                  }   
              }
              System.out.println();
          }
        }

  3. #3
    Jonotron is offline Member
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    Default

    Oh wow, now that I think about it, that makes so much more sense. Thanks a lot!

  4. #4
    collin389 is offline Senior Member
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    Default

    Glad I could help.:)

  5. #5
    Singing Boyo is offline Senior Member
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    Default

    I'm really starting to get annoyed by these ad posts... reported.
    If the above doesn't make sense to you, ignore it, but remember it - might be useful!
    And if you just randomly taught yourself to program, well... you're just like me!

  6. #6
    Fubarable's Avatar
    Fubarable is offline Moderator
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