Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!rochester!uhura.cc.rochester.edu!elmo
From: elmo@uhura.cc.rochester.edu (Eric Cabot)
Newsgroups: comp.lang.pascal
Subject: Re: Can I declare an array using a var in the index?
Keywords: array
Message-ID: <9597@ur-cc.UUCP>
Date: 22 Sep 90 23:29:03 GMT
References: <1994@ac.dal.ca>
Organization: Harry Faversham Memorial Heap Space
Lines: 38

In article <1994@ac.dal.ca> limoges@ac.dal.ca writes:
>I want to write a program which generates 2D arrays of size n x n after n has
>been input from the keyboard by the user running the program. My debugger

If you can stand to have one of the dimensions (either row or col) pre-
defined then why not declare a type of that array size and an 
array of pointers to that type. There isn't really very much overhead
in having that array of pointers.      Addressing the elements
in your matrix isn't particularly messy or difficult. Here are some
program fragments to show you what I mean:

TYPE
    col_arr:record of col: array[1..200] of integer; end;
VAR
    row:array[1..200] of ^col_arr;
    
...

 readln(nrows);
 for i:=1 to nrows do new(row[i]^);
...
  row[5]^.col[5]:=25;  (*sets item at row 5, col 5 to the value 25*)
...

I've used this basic strategy quite a bit for programs that don't
know ahead of time how much memory a given user has on his computer.

You can also further complicate matters by making the col a linked
list, or a linked list of small arrays.

I hope this helps out.


-- 
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Eric Cabot                             |  elmo@{uhura | db1}.cc.rochester.edu
      "insert your face here"          |  elmo@uordbv.bitnet
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