Re: How do I clip a vary length field?

[Vernon Hamberg <vhamberg@xxxxxxxxxxxxxxx>]

Hi Chris

EZDQLSTL is a 4-byte integer, which might look like junk - from the 
looks of the data structure, the actual text is always at the same 
location, after the end of the DS that is defined (note that EZDSQLST00 
is commented out). And coincidentally, the actual is immediately after 
EZDQLSTL, which is why it might work, as Barbara showed.

In another technique, you can set a pointer to the actual text by 
setting a pointer to the start of the DS, then adding the size of the DS 
to the pointer to the start of the DS, in order to get the pointer to 
the actual text, which you might define in any way you want, although 
that will probably not be a varying-length variable in the way I'm 
describing.

Then to get your statement, use the minimum of EZDQLSTL and the length 
of your statement variable. Use that minimum as the length of a 
substring function.

I hope that makes some sense. It is a fairly standard way to get text of 
varying length out of an API, if I am stating it correctly. One thought 
- your DS does not need to have the SQL text in it - you can trust the 
API to allocate the memory need for that statement, so once you have a 
pointer to THAT space, you can get the data at that location in memory.

Vern

On 1/16/2020 11:06 AM, Chris Holko wrote:
> EZDQLSTL appears as junk, using the code sample I posted earlier; it is the simplest way to demo my issue; data_in looks right but I am of the opinion I am making a pointer to the wrong variable.I cannot determine how to put a pointer to what is received on entry to the program as I would have suspected a qualified name for the data structure but that isn’t right.
>
> I am not looking for a gimmick solution and sorry if I implied that earlier. I am trying to receive in the data from the exit point regardless of size and I need to deal with it in more than one size as the program processes the data. Hence the need to move a portion to a much smaller variable. I used 128 because I can easily submit statements larger than that.
>
>
>
> > On Jan 16, 2020, at 10:44 AM, Barbara Morris <bmorris@xxxxxxxxxx> wrote:
> >
> > Vern, in the earlier part of this thread from last year, this technique was
> > discussed (mapping a varying field across an integer followed by a string).
> >
> >    dcl-ds ds;
> >       whatever char(10);
> >       len int(10);
> >       data char(100);
> >       more stuff char(100);
> >    end-ds;
> >
> >    dcl-s varfld varchar(100:4) based(p);
> >    dcl-s p pointer inz(%addr(len));
> >
> > Chris is doing something like that. Whether it's a good idea or not, I
> > think it does work.
> >
> > At least, it works if the length (subfield EZDQLSTL, in Chris's case) is
> > less than or equal to the defined length of the based VARCHAR field.
> >
> > Chris, if you can debug this, what is the value of EZDQLSTL when you do the
> > assignment to Upper?
> >
> > -- Barbara