[fpc-pascal] WORD (2 bytes) to String conversion

[Paul Nicholls]

----- Original Message ----- 
From: "Graeme Geldenhuys" <graemeg.lists at gmail.com>
To: "FPC-Pascal users discussions" <fpc-pascal at lists.freepascal.org>
Sent: Friday, October 23, 2009 11:10 PM
Subject: [fpc-pascal] WORD (2 bytes) to String conversion


> Hi,
>
> I'm reading in a WORD (2 bytes) from a binary file. I can display the
> Hex format of that value without a problem, but I would also like to
> display the String value of that WORD variable. It's the first 2 bytes
> of a file, which contains the "magic number" of the file.
>
> I would like my program to output the following:
>
> -----------------
> Header Section
>  header.ID    (5348h = "HS")
>  ...
> -----------------

Hi Graeme,
    What about something like this (variant records, similar to C unions)? 
(untested, ie. from memory, but shoud work)

TMyHeader = Packed Record
    Case Integer Of
        0 : (ID     : Word);
        1 : (IDStr : String[2]);
End;

You should then be able to file read/write it identically, and also do this:

Var
    Header : TMyHeader;
Begin
    WriteLn(Header.ID) ;// as a word
    WriteLn(Header.IDStr); // as a 2 byte string
End;

cheers,
Paul