Bsave/Bload Arrays

 BBS: Inland Empire Archive
Date: 06-21-92 (12:19)             Number: 1083
From: JEAN CREPEAU                 Refer#: NONE
  To: MARK REIF                     Recvd: NO  
Subj: Bsave/Bload Arrays             Conf: (2) Quik_Bas

In a message to ALL, MARK REIF wrote:
MR=>  I  seem  to  have  a  problem  BSAVEing  and  then BLOADing back to a
    variable. I  did a  program to  read a  .PCX file,  read a mouse button
    push, then GET the  area of screen asked  for to an array.  The I BSAVE
    the array. In another progran I want  to BLOAD the array, so I can  PUT
    the graphic back to the screen. But it seems something is not right. It
    has a  tendency to  make you  use the  CNTL-ALT-DEL keys  quit often. I
    guess maybe possibly it is a  VARPTR or VARSEG problem? The arrays  are
    DIM'd the same, and of the same type (integer).  I am using Quick Basic
    4.5

        Be  sure  you  use  VARPTR  and  VARSEG at the last moment, because
QuickBASIC can move the pointers between instructions. This is incorrect:

DIM X(1000) AS INTEGER
XO=VARPTR(X(0))
XS=VARSEG(X(0))
        [...]
DEF SEG=XS
BLOAD "...",XO

        This is correct:
DIM X(1000) AS INTEGER
        [...]
DEF SEG=VARSEG(X(0))
BLOAD "...",VARPTR(X(0))

        Because every time  you have a  sentence that creates  a new string
like  X$=A$  or  PRINT  LEFT$(X$,1)  or  any  other  string transformation,
QuickBASIC can  change all  the pointers  to be  sure all  the strings  and
arrays will occupy contiguous memory. Also using the FRE() function changes
all the pointers also.
                Jean
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