Yes, You CAN Redim Arrays Via A Ptr To Their Descriptor...

[Eric Cochran]

so as not to have a discussion in the source code forum...

http://www.powerbasic.com/support/pb...ad.php?t=16951

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software: win xp pro sp 2, pb/win 7.04, pb/cc 4.02, win32api.zip v.02-01-05
hardware: amd athlon 64 3200+ (clock speed 2.00 ghz) on a gigabyte k8n pro nforce3-150 mobo, 1 gb pc3200/ddr400 ram, geforce 5 le 128 mb ddr video

[Greg Turgeon]

before anyone makes the mistake of relying on a tactic like this, here are two statements to keep in mind.

from bob:

powerbasic assembler syntax does not support a way to obtain the address of the array descriptor (because the array descriptor contents are not documented, because they may be subject to change in the future).

http://www.powerbasic.com/support/pb...ad.php?t=20142


and lance:

powerbasic has never said that the [internal] array descriptor table would never change, and as discussed above, it is necessary when adding those new features y'all take great care in asking us to build into the language. this is one reason that powerbasic added in the arrayattr() function in pb/win 7.0 and pb/cc 3.0 -- so that arrays could be examined without having to deal with the internal descriptor structure.

http://www.powerbasic.com/support/pb...ead.php?t=7445


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[Eric Cochran]

...and here's how. I looked around for how to do this, before, and couldn't seem to find anything. I was doing some late night tinkering, and somehow managed to figure this out. Hope it helps everybody.

#compile exe
#dim all

type myType
    pString as string ptr     'pString = ptr->string (string array descriptor, here)
end type

sub resizeIt( _               'Just a sub to demonstrate redim'ing...
    byref test() as string, _ ' PB wants a pointer to the descriptor
    newSize as dword )
    
    redim test( newSize )               'Works like a champ.    [img]http://www.powerbasic.com/support/forums/smile.gif[/img]
end sub

function pbmain () as long

    redim stringData ( 5 ) as string
    local this as myType
    this.pString = varptr( stringData() ) 'Normally you'd probably want to point
                                          'to individual elements, but here we
                                          'just want the descriptor's address.
    #if %def(%pb_cc32)
        print ubound( stringData() )
    #else
        MSGBOX ubound( stringData() )
    #endif


    resizeIt( byval this.pString, 10 ) 'It's VERY important that you pass the ptr
                                       'to the descriptor byval in order to dodge
                                       'a parameter mismatch error
    #if %def(%pb_cc32)
        print ubound( stringData() )
    waitkey$
    #else
        MSGBOX ubound( stringData() )
    #endif
end function

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Software: Win XP Pro SP2, PB/Win 7.04, PBCC 4.02, PB Forms 1.5, Win32API.zip v.02-01-05
Hardware: AMD Athlon 64 3200+ (Clock speed 2.00 GHz) on a Gigabyte K8N Pro nForce3-150 mobo, 1 GB PC3200/DDR400 RAM, GeForce 5 LE 128 MB DDR video



[This message has been edited by Eric Cochran (edited November 03, 2005).]