Subj : Re: Mystic structures
To   : Manuel Adorni
From : Nick Andre
Date : Wed Mar 23 2022 05:31 pm

On 23 Mar 22  12:35:53, Manuel Adorni said the following to All:

MA> Anyone have an Mystic BBS structures for QBasic?

Likely not, but its easy to do Pascal to Basic. Use my two function calls:

DECLARE FUNCTION Bas$ (text$)
DECLARE FUNCTION Pas$ (text$)
FUNCTION Bas$ (text$)
    IF LEN(text$) > 0 THEN
        Bas$ = MID$(text$, 2, ASC(MID$(text$, 1, 1)))
    END IF
END FUNCTION
FUNCTION Pas$ (text$)
    IF text$ <> "" THEN
        Pas$ = CHR$(LEN(text$)) + text$
    ELSE
        Pas$ = ""
    END IF
END FUNCTION

You use these Qbasic functions when you work to-and-from Pascal strings 
because the first byte is the length of the string.

So if you had this Pascal structure:

type my_structure = record
 something as string[255];
end type;
var my_data = my_structure;

In Qbasic it would be:

TYPE MYSTRUCTURE
 SOMETHING AS STRING * 256
END TYPE
DIM MYDATA AS MYSTRUCTURE

Then in Qbasic you would use this to retrive the value:

BasicText$ = Bas$(MYDATA.SOMETHING)

For storing a Basic string to Pascal, it would be:

MYDATA.SOMETHING = Pas$(BasicText$)

Booleans and Char Pascal-types are one byte, so STRING * 1 in Basic. A boolean
True equals CHR$(1).

When working with records, you must define the length of the structure in the 
Qbasic OPEN call:

THEPOSITION = 1
OPEN "MYSTIC\COWBELL.DAT" FOR RANDOM AS #1 LEN = LEN(MYDATA)
 GET #1, THEPOSITION, MYDATA
CLOSE #1

Hope this helps,

Nick

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