Text or data files?

[Erland Sommarskog]

(This stems from the discussions of VMS and Unix file systems. I've
added comp.lang.misc and directed follow-ups there. It doesn't
belong to comp.os.vms anymore and I don't read comp.unix.wizards.)

Miles O'Neal (meo at stiatl.UUCP) writes:
>If you even have your data files as text files, debugging
>becomes much easier. For instance, would you rather debug
>98764389437034gh307ytfhr398f39
>or
>12/22/88 01:30 10790 100 100 382 -1
>?
>These are not real data, but examples of what data files I've dealt
>with looked like. The processing to do all this is cheap nowdays,
>so why not use text files if there is no OVERWHELMING reason not to?

There are several advantages of using fixed record files for data,
if the data I have fits to that format. Let's say we have: (This is  
Pascal.)

    Data_record = RECORD
                     Date : PACKED ARRAY(.1..8.) OF char;
                     Time : PACKED ARRAY(.1..8.) OF char;
                     Incident       : Incident_type;   (* Enumerated *)
                     No_of_warnings : integer;
                     Alarmed        : boolan;
                     Username       : PACKED ARRAY(.1..12.) OF char;
                  END;

The simplest way to read and write this is to through a FILE OF Data_record,
if no other programs is to read it. If we store the data in a text file, we
have to parse every line we get. (And what a trouble if Username contains
an LF character.) And since the text file is vulnerable to changes from 
e.g. a text editor, we cannot be sure that the file follows the supposed
format throughout.

As for debugging this only applies if you have to look at the file as such.

>Another thing this buys you is that, in my experience, its easier
>to change file formats if you use text files. It requires a little
>plannning, but in general is a lot less work than doing the same
>thing with any other type of data.

Uh? If you have a text file and change the format you have to rewrite
the parsing and the writing-to file parts. With a fixed format you
change the declaration, and that's all. (Well, you may have to write 
a simple program to convert old files, but you have do to that for 
text files too.)
-- 
Erland Sommarskog            ! "Hon ligger med min b{ste v{n, 
ENEA Data, Stockholm         !  jag v}gar inte sova l{ngre", Orup
sommar at enea.UUCP             ! ("She's making love with best friend,
                             !   I dare not to sleep anymore")