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When you omit the VALUE keyword when passing a parameter, are you passing a
pointer to a pointer? And in this case a pointer to a pointer to a data
structure?
Patrick Conner
www.ConnecTown.com
(828) 244-0822
jpcarr@TREDEGAR.C
OM To: RPG400-L@midrange.com
Sent by: cc:
owner-rpg400-l@mi Subject: RE: Passing pointers
as parms
drange.com
11/28/00 01:49 PM
Please respond to
RPG400-L
Joel
ReRead my earlier post about passing by Reference on a dynamic call.
Since you didn't use the VALUE keyword on your pointer parm, You are
still (like the dynamic call)
passing by Reference.
John
Joel Fritz
<JFritz@sharperim To:
"'RPG400-L@midrange.com'"
age.com> <RPG400-L@midrange.com>
Sent by: cc:
owner-rpg400-l@mi Subject: RE: Passing
pointers as parms
drange.com
11/28/2000 01:06
PM
Please respond to
RPG400-L
Maybe it was something like this:
You have a data structure in your calling program you want to update in the
called program. If you pass a pointer, which appears to be legal and well
behaved in the very limited test I just ran, all you do is copy the data
structure definition into the called program and base it on the pointer
that's passed in. It's the same thing you're doing with slightly and maybe
even inconseqentially fewer lines of code. You are absolutely right that
passing by reference is passing by reference and that's the default in RPG.
Here's my test:
Calling program:
Fqsysprt o f 80 printer
D ptrtst2 pr extpgm('PTRTST2')
D pointer *
D
D datastruct ds
D packed 5p 0 inz(99999)
D char 5 inz('five')
D
D ptrparm * inz(%addr(datastruct))
C
C except before
C callp ptrtst2(ptrparm)
C except after
C eval *inlr = *on
Oqsysprt e before
O 'Before--packed = '
O packed j
O +1 'char = '
O char
O e after
O 'After--packed = '
O packed j
O +1 'char = '
O char
Called program:
D ptrtst2 pr
D pointer *
D
D ptrtst2 pi
D pointer *
D
D datastruct ds based(pointer)
D packed 5p 0
D char 5
D
C eval packed = 11111
C eval char = 'after'
C eval *inlr = *on
> -----Original Message-----
> From: Scott Klement [mailto:klemscot@klements.com]
> Sent: Tuesday, November 28, 2000 9:08 AM
> To: RPG400-L@midrange.com
> Subject: Re: Passing pointers as parms
>
>
>
> If this is a program calling a program (within the same job)
> the program
> _is_ (implicitly) passing a pointer... Thats the way
> parameters work,
> they're passed by "reference" (i.e. a reference to an address in main
> storage)
>
> The exception to this, of course, is when using something
> like QCMDEXC or
> SBMJOB...
>
> So I'm a bit confused as to why you want to pass a pointer
> instead of the
> buffer directly? if you really want to just pass the
> pointer, you could
> do something like this:
>
> Program 1:
>
> D MyBuffer S 32766A
> D pointer S * inz(%addr(MyBuffer))
> D MyField S 1A based(pointer)
> C CALL 'PROGRAM2'
> C PARM MyField
>
>
> Program 2:
>
> D pointer S *
> D MyField S 1A
> D MyBuffer S 32766A based(pointer)
> C *ENTRY PLIST
> C PARM MyField
> C eval pointer = %addr(MyField)
>
>
> But this would yield the same exact results as just passing "MyBuffer"
> directly... so why would you bother??
>
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