[Coco] APPENDING TO A FILE IN RSDOS ?

[William Astle]

You can't just assign to FIELDed variables. Doing so breaks the 
association with the random file. You have to use LSET or RSET.

Also, just opening a file in "R" or "D" (exactly the same) mode should 
create a file that doesn't exist. There's no need for your seed file or 
a "CREATE" command.

On 2023-03-28 08:51, coco--- via Coco wrote:
> To: All
> 
> I continue to have issues with file manipulation in RS-DOS.
> 
> My current objective is to add a 100 space characters to the end of a 
> data file that consists of single byte fields.
> 
> So that given a file X on drive 0 running this program should create
> a file PADDED.DAT on drive 1 who's contents are the contents of X:0 plus
> 100 blank spaces at the end of the file the following code fails I don't
> understand what I am doing wrong.
> 
> To set things up you need a file "X" with no extension on drive 0 and
> a File called SEED.DAT on drive 1. Then at the OK prompts type
> 
> OK DRIVE 1
> OK RUN "PD.BAS"
> FILE NAME? X
> 
> where the source for PD.BAS is shown below.
> 
> 20 'A ROUTINE TO PAD THE DATA WITH 100's OF SPACES.
> 50 PRINT "FILE NAME";
> 60 INPUT F$
> 70 COPY F$+":0" TO F$+".DAT:1"
> 80 OPEN "R",#1,F$,1
> 90 MX=LOF(1)
> 95 PRINT MX;"BYTES FOUND."
> 98 PRINT"READY";
> 99 INPUT R$
> 100 CLOSE #1
> 101 'since I found no CREATE command I try adding to a single byte file'
> 105 COPY "SEED.DAT:1" TO "PADDED.DAT:1"
> 110 OPEN "D",#2,"PADDED.DAT:1",1
> 120 FIELD #2,1 AS DT$
> 180 OPEN "D",#1,F$,1
> 190 FIELD #1,1 AS ST$
> 200 FOR I=1 TO MX
> 210 :GET #1,I
> 220 :DT$=ST$
> 225 :PUT #2,I
> 230 NEXT I
> 235 J=MX+1
> 238 K=J+100
> 240 FOR I=J TO K
> 245 :DT$=" "
> 250 :PUT #2,I
> 260 NEXT
> 270 CLOSE #2
> 280 CLOSE #1
> 300 END
> 
> If someone knows an easier way that works in RS-DOS or what is wrong with
> my code I would like to hear from you.
> 
> Charlie.
>