Re: Variable length fields

[Don Brown <DBrown@xxxxxxxxxx>]

I will try that and let you know.





Don Brown
 



From:   "Craig Richards" <craig@xxxxxxxxxxxxxxxx>
To:     "RPG programming on the IBM i (AS/400 and iSeries)" 
<rpg400-l@xxxxxxxxxxxx>
Date:   09/05/2018 03:55 PM
Subject:        Re: Variable length fields
Sent by:        "RPG400-L" <rpg400-l-bounces@xxxxxxxxxxxx>



Hi Don,

Sorry I don't have a lot of time right now but based on what I think you
are doing I'd code it like this:

Dcl-S OutString VarChar( 100000 ) Inz('');

SetLl JrdUnq Issjrdpf;
ReadE JrdUnq Issjrdpf;
DoW Not %Eof();
   If %Len( JrdDta ) = 0;
      rMessage = 'Zero Length Error';
      Leave;
   ElseIf %Len( OutString ) + %Len( JrdDta ) > 100000;
      rMessage = 'Max length exceeded';
      Leave
   Else;
      OutString += JrdDta;
   EndIf;
   ReadE JrdUnq Issjrdpf;
EndDo;

regards,
Craig

On 9 May 2018 at 05:38, Don Brown <DBrown@xxxxxxxxxx> wrote:

> System is V7R3.
>
> I have recently started using variable length fields and a current 
project
> required a large json string.
>
> Can anyone suggest a good resource for examples with using variable 
length
> fields.  Especially where they are used a part of a return from a
> procedure ?
>
>
> While the reasons why are not so important I have a temporary file where
> if have a field defined with a length of 30000 character
>
> JRDDTA     30000          VARLEN
>
> There can be multiple records in this file making up a json string
> currently with a maximum length of 100000 (but this may increase)
>
> My question is how would you read multiple records from my work file and
> construct the json string.
>
> I ended up doing as follows but it seems not the best option ???
>
> I initially set the length of my variable to the maximum and at the end
> reset to the actual trimmed length.
>
>        rJsonString = *blanks ;
>        %len(rJsonString) = 100000 ;
>
>        setll jrdunq issjrdpf ;
>        reade jrdunq issjrdpf ;
>        dow not %eof(issjrdpf) and overflow = *off ;
>          jrdFound = *on ;
>          if %len(jrddta) > *zero ;
>             if start + %len(jrddta) < 100000 ;
>               %subst(rjsonstring : start : %len(jrddta)) =
>                        %subst(jrddta : 1 : %len(jrddta)) ;
>               start += %len(jrddta) + 1 ;
>               reade jrdunq issjrdpf ;
>             else ;
>               overflow = *on ;
>               rSuccess = *off ;
>               rMessage = 'String exceeds 100000 characters' ;
>
>             endif ;
>          else ;
>            rSuccess = *off ;
>            rMessage = 'Unexpected zero length string' ;
>            leave ;    // Should not get a zero length rlddta field !!!
>
>          ENDIF;
>        ENDDO;
>
>
>
> Don Brown
>
>
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