declaring 2d arrays

This is a discussion on declaring 2d arrays within the C Programming forums, part of the General Programming Boards category; I am trying to declare a 2d array with a integer as the size the integer is sent from another ...

  1. #1
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    declaring 2d arrays

    I am trying to declare a 2d array with a integer as the size the integer is sent from another function.

    Is this possible?
    because i can't get it to work!

  2. #2
    and the hat of wrongness Salem's Avatar
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    > Is this possible?
    It is in C++
    And will be when your compiler supports the latest C99 standard

    But until then, you need this
    Code:
    #include <stdlib.h>
    void foo ( int size ) {
      int **arr;
      int i;
    
      // allocate a 2D array
      arr = malloc( sizeof(int*) * size );
      for ( i = 0 ; i < size ; i++ ) arr[i] = malloc( sizeof(int) * size );
    
      // use arr as  arr[row][col]
      // as if you had declared int arr[size][size];
    
      // free the allocated array
      for ( i = 0 ; i < size ; i++ ) free( arr[i] );
      free( arr );
    }

  3. #3
    Registered User Zeeshan's Avatar
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    can only be achieved using dynamic allocation

    i.e. using malloc/free for C
    or using new/delete for C++

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