Hi Nilesh,
Your "dglsed1" field is only 10 bytes long. Your $current array is 120
bytes long -- therefore, the first 10 bytes of the $current array (which
is one element) is overlaying dglsed1. The remaining 110 bytes will
contain whatever happens to (by chance) come after dglsed1 in the
computer's memory.
They MIGHT be the values of dglsed2, dglsed3, dglsed4, etc. But they
might not. it all depends on luck! You haven't done anything (at
least, in the code you posted) that forces them to be contiguous, and
therefore your program won't work consistently.
You see, when RPG reads data from a database, it doesn't read the entire
record all into memory at once as one big contiguous chunk of data.
Instead, it reads one field at a time, copies it into an RPG variable
(and does conversion if necessary), then reads the next field, and does
conversion, etc. The program variables do not necessarily have to be
right next to each other in memory -- and in fact, they frequently
aren't. Therefore, you can't just assume they'll be contiguous.
To solve your problem, you need to FORCE them to be contiguous, and you
do that by putting them into a data structure. For example:
D MyDS ds
D dglsed1
D dglsed2
D dglsed3
D dglsed4
D dglsed5
D dglsed6
D dglsed7
D dglsed8
D dglsed9
D dglsed10
D dglsed11
D dglsed12
When fields are in a data structure, they have a fixed from/to position
within the data structure. Since a data structure is one object in
memory, and since RPG is documented to assign the from/to positions to
be contiguous, you know that the dglsed fields will be contiguous in
memory -- so now you can set your basing pointer to the address of
dglsed1 with confidence.
Having said that... Why even bother with pointer logic? Why not just
do the following? It's much safer, and it's much easier for the next
programmer to understand:
D MyDS ds
D dglsed1
D dglsed2
D dglsed3
D dglsed4
D dglsed5
D dglsed6
D dglsed7
D dglsed8
D dglsed9
D dglsed10
D dglsed11
D dglsed12
D $current like(dglsed1) dim(12)
D overlay(myDS:1)
The only time I'd use pointer logic like you've used is if I'm reading
the whole record into a data structure for some reason. (For example,
so I could take advantage of a qualified name.) In that case, I'd use
pointer logic -- but, in that case, the fields are already in a DS, so I
wouldn't have to worry about the data being contiguous -- it'd be
contiguous already.
Hope that helps.
Butala, Nilesh wrote:
Hi
See following code, it compiles file but when I run it gives different results. Any ideas?
*****************************************************************
* current year array *
*****************************************************************
d $current s based($curptr)
d like(dglsed1) dim(12)
d ascend
d $curptr s * inz(%addr(dglsed1))
c dglscmpny chain(n) dbifgls1
*
The array value is not correct
EVAL $current
$CURRENT(1) = '2007-10-31'
$CURRENT(2) = ' 2008'
$CURRENT(3) = '-07-31 '
$CURRENT(4) = ' 2008-08-'
$CURRENT(5) = '31 20'
$CURRENT(6) = '08-09-30 '
$CURRENT(7) = ' 0001-0'
$CURRENT(8) = '1-01 '
$CURRENT(9) = '2006-10-31'
$CURRENT(10) = ' 2006'
$CURRENT(11) = '-11-30 '
$CURRENT(12) = ' 2006-12-'
In file
DGLSCMPNY B B 1 COMPANY 1 4 0
DGLSED1 L B PER_END_DATE_01 56 10
DGLSED2 L B PER_END_DATE_02 66 10
DGLSED3 L B PER_END_DATE_03 76 10
DGLSED4 L B PER_END_DATE_04 86 10
DGLSED5 L B PER_END_DATE_05 96 10
DGLSED6 L B PER_END_DATE_06 106 10
DGLSED7 L B PER_END_DATE_07 116 10
DGLSED8 L B PER_END_DATE_08 126 10
DGLSED9 L B PER_END_DATE_09 136 10
DGLSED10 L B PER_END_DATE_10 146 10
DGLSED11 L B PER_END_DATE_11 156 10
DGLSED12 L B PER_END_DATE_12 166 10
This file is created using create table and logical is created using create index. Company is key index.
Thanks
Nilesh
midrange.com
