Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!unmvax!pprg.unm.edu!hc!lll-winken!uunet!tektronix!percival!bucket!leonard
From: leonard@bucket.UUCP (Leonard Erickson)
Newsgroups: comp.lang.pascal
Subject: Re: Using logical device LST: in TP5
Message-ID: <1381@bucket.UUCP>
Date: 2 May 89 04:48:20 GMT
References: <17691@cup.portal.com>
Reply-To: leonard@bucket.UUCP (Leonard Erickson)
Organization: Rick's Home Grown Unix; Portland, OR
Lines: 61

In article <17691@cup.portal.com> Dex@cup.portal.com (Paul Dex Durden) writes:
<   I've been programming at UAH using TP3.02a and noticed that in TP5 I
<couldn't open a file assigned to the logical device 'LST:' like I could in
<TP3.  I know you can use the variable LST in the write statements to send
<the output to the printer but below is what I had originaly wrote and would
<like to keep, rather than having to double up on code and rewrite it for
<output to disk and printer.

<   In TP3 the below code works but in TP5 I get a 'File not found error'
<   when REWRITing Out when out is assigned to LST:
<
<USES TURBO3,CRT,PRINTER;
<
<VAR
<   I : INTEGER;
<   OUT : TEXT;
<
<
<BEGIN
<   FOR I:=1 TO 2 DO
<      BEGIN
<         IF I = 1 THEN
<            BEGIN
<               ASSIGN(OUT,'LST:');     {Direct output to printer}
<               REWRITE(OUT);
<            END
<         ELSE
<            BEGIN
<               ASSIGN(OUT,'A:FILENAME.TXT'); {Direct output to FILENAME}
<               REWRITE(OUT);
<            END;
<
<         WRITELN(OUT,'DATA HERE');
<         WRITELN(OUT,'More data');
<         IF I = 1 THEN
<            WRITELN(^L);   {Form feed}
<
<         CLOSE(OUT);
<
<      END; {FOR}
<END.

 In TP3 'lst' is an *internal* logical device that the compiler maps to
the DOS device PRN: (or possibly LPT1:).

In TP4 and 5 'lst' is a pre-assigned filename that you get by using the
printer unit. (ie writeln(lst,x,y,z) will write x, y, and z to the 
printer.

TP 4 & 5 use the *DOS* logical devices iin assign statements.
Thus you need to ASSIGN(OUT,'PRN:') (or use LPT1:). Note also that in
TP4 lst was opened in 'cooked' mode instead of 'raw' (ie binary) mode.
This meant that tabs got expanded, many control characters got munged,
and ^Z closed the file.... (oops!) I'm not sure if TP 5 kept this
'feature' or not.

-- 
Leonard Erickson		...!tektronix!reed!percival!bucket!leonard
CIS: [70465,203]
"I'm all in favor of keeping dangerous weapons out of the hands of fools.
Let's start with typewriters." -- Solomon Short