Re: dynamic arrays

[Marcus G. Daniels]

>>>>> "JM" == James Marshall <address@hidden> writes:

JM> I want to create an array of integers at runtime... in C++ I'd do 
JM> the following:

int *array, xsize, ysize;
xsize=10;
ysize=10;
array=new int[xsize][ysize];

JM> How do I do this with Swarm and objective C? From my fiddlings it 
JM> seems alloc is replaced by create... can you use the create message 
JM> with the default types? 

Also, since Objective C is based on GNU C, you can have dynamically
sized arrays, and closure over variables (e.g. xsize)...

#include <stdlib.h>
#include <stddef.h>
#include <stdio.h>

main (int argc, char **argv)
{
  size_t xsize, ysize, xi, yi;
  int *permanent_array;

  {
    void print (size_t xi, size_t yi, int array[][xsize])
    {
      printf (" %d", array[yi][xi]);
    }
    
    if (argc < 3)
      {
        fprintf (stderr, "Specify X and Y dimensions\n");
        exit (1);
      }
    xsize = atoi (argv[1]);
    ysize = atoi (argv[2]);
    {
      int temporary_array[ysize][xsize];
      
      for (yi = 0; yi < ysize; yi++)
        for (xi = 0; xi < xsize; xi++)
          temporary_array[yi][xi] = xi * yi;
      
      permanent_array = malloc (sizeof (temporary_array)); 
      if (permanent_array == NULL)
        abort ();
      memcpy (permanent_array, temporary_array, sizeof (temporary_array));
    }
    for (yi = 0; yi < ysize; yi++)
      {
        for (xi = 0; xi < xsize; xi++)
          print (xi, yi, (void *)permanent_array);
        putchar ('\n');
      }
  }
} 

                  ==================================
   Swarm-Support is for discussion of the technical details of the day
   to day usage of Swarm.  For list administration needs (esp.
   [un]subscribing), please send a message to <address@hidden>
   with "help" in the body of the message.
                  ==================================