Re: Alternating tables

[boldt@xxxxxxxxxx]

Rob wrote:
>I'm a different Rob, but I'll take a stab.  Let's use a simple table:
>
>While this might be better in a lookup file, for the sake of our example
let's assume we used a >compile time table.
>
>¦   D*Name++++++++++ETDsFrom+++To/L+++IDc.Keywords++++++++++++++++++++

>¦   DTABEMP                          3A 0 DIM(4) PERRCD(1) CTDATA

>¦   DTABPAY                          7S 2 DIM(4) ALT(TABEMP)

>¦
C*0N01Factor1+++++++Opcode(E)+Factor2+++++++Result++++++++Len++D+HiLoEq..

>¦   C* The LOOKUP operation searches TABEMP for an entry that is equal to

>¦   C* the contents of the field named EMPNUM. If an equal entry is

>¦   C* found in TABEMP, indicator 09 is set on, and the TABEMP entry and

>¦   C* its related entry in TABPAY are made the current elements.

>¦   C     EMPNUM        LOOKUP    TABEMP        TABPAY
09
>¦   C* If indicator 09 is set on, the contents of the field named

>¦   C* HRSWKD are multiplied by the value of the current element of

>¦   C* TABPAY.

>¦   C                   IF        *IN09

>¦   C     HRSWKD        MULT(H)   TABPAY        AMT               6 2

>¦   C                   ENDIF

>     ...
>**  Employee table.  First 3 digits are employee #  Rest is rate.
>0010000950
>0020000725
>0030001375
>0040001000

One minor point about alternating tables/arrays:  Alternating
format deals only with the loading of array/table values.  The
two arrays or tables have no relationship to each other other
than that.  In particular, the two tables specified in the
LOOKUP opcode do not have to be tables defined in alternating
format.  (Also, you can even mix arrays and tables using
alternating format.)

Oh by the way, the preferred syntax for compile-time array/table
data is:

**CTDATA TABEMP Employee table.  First 3 digits are employee #  Rest is
rate.
0010000950
0020000725
0030001375
0040001000

This way, you don't have to code the compile-time data in the
same order as the array/table definition.  Note that you can't
mix the two styles of compile-time data definition in the same
module.  Once you use the **CTDATA syntax in a module, you
can't use the ** syntax.  (But then again, when you know about
**CTDATA, why would you even think about using the old syntax?)

(This was actually part of the IBM Corporate Standard for RPG
during the S/38 RPG III days, but was never implemented until
RPG IV!)

Cheers!  Hans

Hans Boldt, ILE RPG Development, IBM Toronto Lab, boldt@ca.ibm.com


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