What is the de-facto method for handling typed files where the
record lengths and variables are unpredictable (i.e. dependent on
the content)?

For example, you can't define something like this.........

   TMyFileData = record
      header1 : integer;
      header2 : (( anywhere from 3 to 9 integers, specified by header1)) ;
      header3 : string[40];
      header4 : (( 2 real numbers ));
      etc...
   var MyFileData = TMyFileData;
   read(infile,MyFileData);

However I don't know of any way to just go in and do.........
     read(infile,header1);
     for n := 1 to header1 do read(infile,header2[n]);
     read(infile,header3);
     read(infile,header4);

as Delphi always wants a fixed structure of some kind.

Do I have to just read one byte at a time and assemble my variables
on-the-fly?

This seems a bit stupid as Perl is not fussy over reading whatever
type I want out of any file at any time.

MJ

just create a  FILE ..
Var
  F:FILE:
Begin
 AssignFile(F,'asdsda');
 Reset(F, 1); // Set record size to 1 byte.
 //
  now use the BlockWRite, BlockRead, Seek etc..

In article <59b1f153.0304101048.77c15...@posting.google.com>,

Use a TStream descendant (TMemoryStream, TFileStream etc)  like (untested) ...

type
  THeader3 = string[40];
  THeader4 = array[0..1] of double;
var
  MS : TMemoryStream;
  MyFileData : TMyFileData;
  H1 : integer;
  H2 : array[0..8] of integer;
  H3 : string[40];
  H4 : THeader4;
  PtrMyFileData : PMyFileData;
  // etc
begin
  MS := TMemoryStream.Create;
  with MS Do begin
    LoadFromFile('MyFileOfData.dat');
    Read(H1, SizeOf(integer));
    Read(H2, SizeOf(integer) * H1);
    Read(H3[1], SizeOf(THeader3));
    Read(H4, SizeOf(THeader4);
    // etc
  end;
  PtrMyFileData := AllocMem(SizeOf(TMyFileData));
  with PtrMyFileData^ do begin
    Header1 := H1;
    Header2 := H2;
    Header3 := H3;
    Header4 := H4;
    // etc

  // finally
  MS.Free;
end;

You can also write small functions which read and return the appropriate stuff.
I use that a lot of the time to store and load data from strings, integers,
doubles, records etc.

There is a small help file I wrote on streams, which is available on the FAQ
site for this NG. Can't remember where it is but someone will post the site I'm
sure.

Alan Lloyd
alangll...@aol.com

None. Typed files are defined as a lineair sequence of constant records.

So you'll have to go untyped, don't forget to set the 2nd parameter of reset to 1.

Streams are built on top of these.