Hey FOLKS

check this out: I can't seem to figure it out

I declare 4, variable size, 2 dimensional arrays as follows

typedef int** BOARD_T;
BOARD_T PlayBoard=NULL;      /* PLAY board */
BOARD_T Libs=NULL;           /* liberty matrix */
BOARD_T ScoreBoard=NULL;     /* Markup Board for ScoreBoard() */
BOARD_T CountBoard=NULL;     /* Markup Board for Count() */

then I intialize each of them when the size is determined, as follows

   *PlayBoard = (int *) calloc(sizeof(int),size);
    for (i=0; i<BoardSize; i++)
      PlayBoard[i] =(int *) calloc(sizeof(int),size);

   *Libs = (int *) calloc(sizeof(int),size);
   for (i=0; i<BoardSize; i++)
      Libs[i] =(int *) calloc(sizeof(int),size);

   *CountBoard = (int *) calloc(sizeof(int),size);
   for (i=0; i<BoardSize; i++)
      CountBoard[i] =(int *) calloc(sizeof(int),size);

   *ScoreBoard = (int *) calloc(sizeof(int),size);
   for (i=0; i<BoardSize; i++)
      ScoreBoard[i] =(int *) calloc(sizeof(int),size);

Now everything works pretty well - but when I modify CountBoard, or Libs
I am also modifying PlayBoard

It is like they are the same piece of memory!!
I thought what I was doing was declaring 4 separate 2d arrays but instead
I get 4 pointers to a single 2d array

Any clues?  What am I doing wrong?
I thought I was right!

Thanx in advance for any help

BTW : I am compiling on a Pentium 160 using DJGPP v2.01
                                (read gcc for DOS)

-----------------------------------------------------------------------------
GREGORY A EISENBERG
Computer Science Undergraduate Society PREZ

                                http://www.*-*-*.com/ ~tele
check out THREE WAY STREET       http://www.*-*-*.com/ ~tele/3way

"Kirk to Enterprise -- beam down yeoman Rand and a six-pack."
Tue Dec 23 03:38:01 EST 1997

--

    PlayBoard = (int **) calloc(sizeof(int*),size);

Make sure you initialize Playboard before you ever use *Playboard
(remember: *ptr dereferences ptr).

You'll also want to make sure you're using sizeof(int*).  A pointer to
int
may have a different size than the size of an int.

I'm surprised you didn't get a run-time error.  

--
Bryan J. Polyak - Senior Programmer Analyst
Raytheon STX - EROS Data Center, Sioux Falls, SD  57198

Fax:   (605)594-6940 | http://edcwww.cr.usgs.gov/
--

OK, here's a clue.  Learn a de{*filter*}, single-step through the code
and check the assigned values.  Merry Christmas.

--
--Pierre Asselin, Westminster, Colorado


--

PlayBoard = (BOARD_T) calloc(sizeof(int *),size);
     for (i=0; i<BoardSize; i++)
       PlayBoard[i] =(int *) calloc(sizeof(int),size);

etc.

I'm curious if the paramaters for calloc are reversed, i.e. calloc(size,
sizeof(...)).

-- Sean

--

--

Chris Volpe                     Phone: (518) 387-7766
GE Corporate R&D            Fax:   (518) 387-6981
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Schenectady, NY 12301           Web:   http://www.*-*-*.com/ ~volpecr
Note: News postings do not constitute a GE Corporate communication
--

Well michael - Thanx for the info - but your reply lacked a solution

Actually about fif{*filter*} minutes after emailling the newsgroups I figured
this bug out
I had been doing:

    PlayBoard = (int **) calloc(sizeof(int *),size);
     for (i=0; i<BoardSize; i++)
       PlayBoard[i] =(int *) calloc(sizeof(int),size);

Now it works great!!

Thanx
-----------------------------------------------------------------------------
GREGORY A EISENBERG
Computer Science Undergraduate Society PREZ

                                http://www.*-*-*.com/ ~tele
check out THREE WAY STREET       http://www.*-*-*.com/ ~tele/3way

Fairy Tale, n.:
        A horror story to prepare children for the newspapers.
Tue Dec 23 22:36:27 EST 1997
--

(posted and mailed)

[snip]

You declare four double pointers, initializing each to NULL, and
never give them any other value.  Hence they all point to the same
location, which is of type pointer to int, and whose address is zero.

Then you assign a series of pointer values to the location to which
they all point, each value overlaying the previous one.  At that
point, *PlayBoard, *Libs, *ScoreBoard and *Board are all the same
variable by four different names, so naturally they all point to the
same place.

In most operating systems you would have crashed and burned by now,
by assigning through a null pointer.

http://home.swbell.net/mck9/cobol/cobol.html
--

(posted and mailed)

[snip]

You declare four double pointers, initializing each to NULL, and
never give them any other value.  Hence they all point to the same
location, which is of type pointer to int, and whose address is zero.

Then you assign a series of pointer values to the location to which
they all point, each value overlaying the previous one.  At that
point, *PlayBoard, *Libs, *ScoreBoard and *Board are all the same
variable by four different names, so naturally they all point to the
same place.

In most operating systems you would have crashed and burned by now,
by assigning through a null pointer.

http://home.swbell.net/mck9/cobol/cobol.html
--