Unpack an extra byte and ignore the extra digit and sign.
On Tue, Apr 29, 2025 at 6:19 PM Bernd Oppolzer <[email protected]>
wrote:
> Topic drift:
>
> a really useful enhancemant for COBOL and other mainframe language IMO
> would be:
>
> the possibility to define DECIMAL variables, which are REALLY unsigned,
> that is, they don't have a sign nibble.
>
> x'00123456' as an example (8 decimal digits, unsigned).
>
> Because that's what we have all the time in legacy VSAM based systems,
> where clever architects of the past put
> numeric keys in packed decimal format WITHOUT SIGN in legacy datasets.
> Such fields (in key or non-key positions)
> are defined as CHAR fields, like PIC X(4) in the case above, but in
> reality they are something like PIC S9(8) COMP-3 "UNSIGNED".
>
> But because it is impossible to define it like that (at least in "my"
> version of COBOL - on VSE), we have to implement some
> logic to convert such fields to, say, PIC 9(8) USAGE DISPLAY, so that
> they can be shown on CICS screens or on the printer.
>
> Kind regards
>
> Bernd
>
>
> Am 29.04.2025 um 16:16 schrieb Schmitt, Michael:
> > In COBOL "unsigned" really means "not signed", which means that the
> number can only have a positive value or zero.
> >
> > From a practical point of view:
> >
> > * An unsinged binary can hold larger numbers, depending on compile
> options
> >
> > * Unsigned is generally better for zoned decimal ("usage display"). 123
> as a signed zoned decimal (PIC S999) would be stored as x'F1F2C3', while as
> unsigned (PIC 999) it would be F1F2F3. The problem is when you print or
> display it: the signed version would print as 12C. I hate that.
> >
> > On the other hand, singed fields enable more efficient code.
> >
> >
> > Fun fact: CA Easytrieve also has signed and unsigned numbers, but
> there's no obvious way to define it. The way it works is a number with
> decimal positions is signed (aka "quantitative"), a number without is
> unsinged:
> >
> > Field 4 P = 4 byte unsigned packed decimal
> > Field 4 P 2 = 4 byte signed packed decimal with 2 decimal positions
> >
> > So how do you do a signed field with 0 decimals? Easy:
> >
> > Field 4 P 0
> >
> > -----Original Message-----
> > From: IBM Mainframe Discussion List <[email protected]> On
> Behalf Of Andrew Rowley
> > Sent: Monday, April 28, 2025 6:40 PM
> > To: [email protected]
> > Subject: Re: Packed decimal sign nibbles
> >
> > On 29/04/2025 9:32 am, Seymour J Metz wrote:
> >> The decimal instructions treat F zones as positive.
> > That's always been my understanding. But I'm intrigued by the statement
> > that it means unsigned in COBOL. Is there a practical difference? Or is
> > it just a difference e.g. for formatting output?
> >
> > --
> > Andrew Rowley
> > Black Hill Software
> >
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--
Mike A Schwab, Springfield IL USA
Where do Forest Rangers go to get away from it all?
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