Correct usage of malloc and free for 2D array

This is a discussion on Correct usage of malloc and free for 2D array within the C Programming forums, part of the General Programming Boards category; I have a program that requires to create and delete a 2D array of variable size, hence the dynamic usage. ...

  1. #1
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    Correct usage of malloc and free for 2D array

    I have a program that requires to create and delete a 2D array of variable size, hence the dynamic usage. However I wish to ask a simple question about the correct or recommended usage. For example, where should I reallocate the memory, should I simply free up the memory and use another allocation of memory i.e. memory allocation double etc should be done once...


    or should be done in the loop


    double **ptrBeadArrayOld = NULL;
    ptrBeadArrayOld = (double **)malloc(BeadTotal * sizeof(double *));
    for (i = 0; i< BeadTotal; i++)
    free_2d(ptrBeadArrayOld);

    or do I simply declare once?

    double **ptrBeadArrayOld = NULL;

    at the beginning of the program?? Thanks
    Last edited by disruptivetech; 10-20-2008 at 05:15 AM.

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    Are you asking about whether you should determine the final size of the array and then allocate once, versus filling up the array and expanding when necessary?
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