[Info-vax] DEC BASIC: How to read a sequential

[Hein RMS van den Heuvel]

On Friday, April 13, 2012 8:41:23 AM UTC-4, StGallen wrote:
> All,
> DEC Basic 1.3. VMS 7.3.2
> 
> I need to open a sequential file with variable record length.

Input or output?

> How can I do this, especially since I cannot define the size of the STRINGS in
> the MAP file?

Other have explained alternatives.

You can still use a MAP if you like. 
Just declare a large enough string ( STRING my_data = 200 ) 
Don't make it too large because the record will be zero-filled on each GET
Process taking the actual count into consideration (RECOUNT and LEFT$)
The silly program below shows that the record cleared beyond recount.
There will not be a CR-LF unless explcit in the record,
and no 'see through' of prior longer reads.
 
Hein

1       OPTION TYPE = EXPLICIT
        on error go to hell!
!
        DECLARE INTEGER I, L
        MAP (buf) string my_record = 2000
        MAP (buf) string x=20, y=20, z=20
        OPEN "login.com" FOR INPUT AS FILE #1, RECORDTYPE ANY, MAP buf
        FOR i = 1 to 5 step 1
                GET #1
                L = RECOUNT
                PRINT I,L, "<"; X; ">", "<"; Y; ">", "<"; Z; ">"
        NEXT I
        GOTO 2

 hell:  PRINT ERT$(ERR) UNLESS ERR = 11
        RESUME 2
 2       END