Path: utzoo!utgpu!news-server.csri.toronto.edu!qucdn!spraggej
Organization: Queen's University at Kingston
Date: Friday, 19 Apr 1991 23:49:43 EDT
From: John G. Spragge <SPRAGGEJ@QUCDN.QueensU.CA>
Message-ID: <91109.234943SPRAGGEJ@QUCDN.QueensU.CA>
Newsgroups: comp.lang.pascal
Subject: Re: need dynamic array on heap
References: <1991Apr12.234843.9031@ux1.cso.uiuc.edu> <4816@gumby.Altos.COM>
 <7294@vice.ICO.TEK.COM> <91107.174405SPRAGGEJ@QUCDN.QueensU.CA>
 <7309@vice.ICO.TEK.COM>

In article <7309@vice.ICO.TEK.COM>, bobb@vice.ICO.TEK.COM (Bob Beauchaine) says:
>
>>>
>>>  type byte_buf = array[1..64000] of byte;
>>>       byte_buf_ptr = ^byte_buf;
>>>
>>>  var  buffer : pointer;
>>>  .
>>>  .
>>>  getmem(buffer,somesize); { Allocate only as many bytes as you need }
>>>  byte_buf_ptr(buffer)^[2] := somevalue;
>>
>>Actually, since GETMEM takes ANY pointer type, you don't need
>>the typecast. You don't have to allocate enough memory for the
>>structure you're loading; you just have to be sure your code
>>will manage dynamic structures correctly.
>>
>
>  You most certainly do need the typecast.  Notice the getmem call
>  does not use the typecast; it's the reference to the pointer
>  as a pointer to an array of bytes that requires the typecast.

The way I do it is:

TYPE
   pflexb  =   ^flexb;
   flexb   =   ARRAY [1 .. 64000] OF CHAR;

VAR
   fb      :   pflexb;
   c       :   INTEGER;

BEGIN
   GETMEM (fb, 2000);
   FOR c := 1 TO 2000 DO
       fb [c] := 'm';
END.

I think yo'll find that works well enough, withot requiring a
typecast. To anyone who thoght I was saying yo don't need a
typecast the dereference a generic pointer, I apologize.

disclaimer: Queen's University supplies me with computer services, not
            my opinions.

John G. Spragge