Dissappearing data in array...

Posted on 2001-06-20
Last Modified: 2010-04-02
I am using MS Dev C++ 6.0 under Win2k.  The program is a simple console program to split up a data set into 12 frames and will rearrange the data.  The problem is as follows.  Where I know stuff is ok I have summarized.  The problem is that depending where I do the cout statement the data I dumped into the array is printed.  The values are read from a file where some characters have to be skipped.  That is fine.  The output should be values like 1.0013 and so on.

main() ...
char *arrIJK[40][54][54];
open file...
for loops for k < 40 and j < 54 with k++ and j++
  for(int i=0; i < 54; i++)
    fgets(tmp_buffer, 3, r_file);
    fgets(tmp_buffer, 7, r_file);
    arrIJK[k][j][i] = tmp_buffer;
    cout << arrIJK[k][j][i];      // prints ok
    fgets(tmp_buffer, 3, r_file);
    cout << arrIJK[k][j][i];      // prints blank
Question by:ancient1
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Accepted Solution

MDarling earned 300 total points
ID: 6209734
Are you using the tmp_bufrer over and over again and expecting the data to persist?

You have a 3 dimensional array of char pointers.

All you seem to be doing is setting each element in turn to point to the same buffer.

Is this what you want?

I'm guessing it's printing blank because it's read blank.

Try this...

cout << "tmp_buffer is " << tmp_buffer << endl
     << "arrIJK[k][j][i] is " << arrIJK[k][j][i] << endl;

and see if you don't get blanks for both.

Fundamentally, though, your use of the pointer array looks flawed.  You need to dynamically allocate a tmp_buffer for each element.

LVL 30

Expert Comment

ID: 6210055
Please post the comple code for main(), even if you think it's unrelated to the problem.
LVL 14

Expert Comment

ID: 6210226
>>arrIJK[k][j][i] = tmp_buffer;
error, becouse you change tmp_buffer all time (and
change arrIJK[k][j][i] in parallel.
Right code is:
arrIJK[k][j][i] = strdup(tmp_buffer);
and after end of function you must free data:

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LVL 14

Expert Comment

ID: 6240613
ancient1, I hope , you use my way to store data.
LVL 11

Expert Comment

ID: 7014548
Dear ancient1

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Expert Comment

ID: 7030983
Force accepted

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