::: Area #157 (comp.sys.acorn.programmer)
Message: #39995 (Read 4 times, has 0 replies, 1508 bytes)
Date   : Thu Feb 18 01:45:42 1999
From   : Jonathan Graham Harston of fidonet#2:254/27
Subject: BBC BASIC float size (reply to #39936)

> Message-ID: <19990216.000103.13@cheesey.demon.co.uk>

Markus Huber wrote:
> How can I get the information of the BBC BASIC float variable size? (5
> or 8 bytes) I am in hope for an official solution.

I presume you mean how can a running program find out the size of the
floats it is using, and 'look in the manual' is not the required answer...
8)

Rik Griffin wrote:
> Here's a nasty idea:
> DIM a% 8
> FOR l%=0 TO 7 STEP4:a%!l%=-1:NEXT

Very nasty, as by the time l% is 6, it will overwrite memory past the end
of the reserved space, filling a%?6, a%?7, a%?8 and a%?9.

Try:

REM FNSizeOfReal
REM ------------
REM Returns the size of real variables being used by the program
REM Currently only knows about 5-byte and 8-byte reals
REM Causes 8-byte memory leak on every call
REM Basic V onwards only (use of |)
:
DEFFNSizeOfReal
  LOCAL A%
  DIM A% 7         :REM Reserve 8 bytes of memory
  A%!0=-1          :REM Fill all 8 bytes with &FF
  A%!4=-1
  |A%=0            :REM Fill either first 5 bytes or 8 bytes with &00
IFA%?5=0:=8 ELSE =5

--
J.G.Harston (JGH BBC PD Library) 70 Camm Street, Walkley, SHEFFIELD S6 3TR
jgh@arcade.demon.co.uk - Running on BBCs & Masters with SJ MDFS FileServer
Z80+6502/CoPro+Tubes/Econet+SJ -- http://www.libdems.force9.co.uk/usr/jgh/
--- ARCbbs RISC OS [1.64á32c]
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