Re: definintion of signed integer?

Thanks Charles and Alan.
I found that the unsigned PositiveValue was indeed causing issues.
Changing PositiveValue to 3i 0 (option 1)
Alleviated the problem. Leaving PositiveValue at 3u 0 and using the
assignment " NegativeValue = %int(PositiveValue) - 21;" (2a)
still threw MCH1216, even with the values in the original example. Hmmm.

(You'd think a business language should be a bit more forgiving in basic
math functionality, but my expectations are often unrealistic)

-Michael


-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx [mailto:rpg400-l-bounces@xxxxxxxxxxxx]
On Behalf Of Charles Wilt
Sent: Monday, September 27, 2010 4:38 PM
To: RPG programming on the IBM i / System i
Subject: Re: definintion of signed integer?

I'm pretty sure you're being bit by eval's handling of intermediate
results...

Since PositiveValue is an unsigned integer, and 21 is a constant that
could also be considered an unsigned integer, eval is treating the
results as an unsigned integer which obviously won't hold a negative
value.

Solution:
1) redefine PositiveValue as a signed integer
2) let eval know you're dealing with signed values
a) NegativeValue = %int(PositiveValue) - 21;
b) NegativeValue = PositiveValue + (-21);

note that 2a) would blow up given a PositiveValue greater than 127.

I'd go with option 1) myself....

HTH,
Charles



On Mon, Sep 27, 2010 at 4:04 PM, Koester, Michael
<mkoester@xxxxxxxxxxxxx> wrote:

I have a variable defined "3i 0", local to a subprocedure that I expect
could be any whole number value from -128 to +127, per my understanding
of a signed integer. When my subprocedure puts what I expect to be a
minus 18 into the field, I get the dreaded "MCH1216 - too small to hold
result" crash & burn.

I'm sure I can fix it instantly by defining packed numerics, but I need
to understand the rules.

D PositiveValue 3u 0
D NegativeValue 3i 0
/free
PositiveValue = 3;
NegativeValue = PositiveValue - 21;
[down in flames we go]
/end-free

What could be so tough about subtracting 3 from 21 and expecting -18?
Please set me straight here. It's an SQLRPGLE program on a 6.1 box.

Many thanks.
Michael Koester

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