Variable length fields

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