RE: MOVE vs. EVAL

["Bob Cozzi" <cozzi@xxxxxxxxx>]

Douglas,
I have 4 daughters so I feel your pain. Two got married this year alone...
so I'm back working again having gone nearly broke on those weddings!!
Yikes! :)

EVAL is "copy left-justified" whereas MOVEL is copy left-justified. EVALR is
copy right-justified, whereas MOVE is copy right-justified.
EVAL does not implicitly convert data types between character/numeric or
date fields and non-date fields. You need to use built-in functions for
those.
EVAL is an assignment statement not a copy statement. This means the target
is always replaced with EVAL.
EVALR can only be used with non-numeric, non-mathematical expressions. Don't
know why, but that's the way it is.

EVAL is typically slower than the MOVEL opcode at runtime because IBM often
generates temporary variables and does multiple copies depending on what
you're doing.

For character fields & Data Structures, MOVE and MOVEL effectively utilize a
built-in %SUBST function. That is the target (Result field) of a MOVE is
only impacted by the number of bytes in the source (Factor 2). If Factor 2
is shorter than the Result, not all of the result is overlaid.
If Factor 2 is longer than the Result, all the bytes in the Result are
replaced.
If you include the P (Pad) operation extender as in MOVEL(P) then any bytes
in the Result field beyond the length of Factor 2 are cleared.

For Numeric values, the MOVE opcode is converted into a cpynv (copy numeric
value) MI instruction (typically) and the data in Factor 1 is copied to the
Result field.

For a mix of character source and numeric target, the data is converted to
numeric and copied. General errors occur when the data doesn't convert
correctly.
For a mix of numeric source and character target, the data is converted to
character and (if MOVE is used) copied to the target right-justified and
zero filled.

-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx [mailto:rpg400-l-bounces@xxxxxxxxxxxx]
On Behalf Of Douglas W. Palme
Sent: Thursday, January 13, 2005 8:28 AM
To: RPG programming on the AS400 / iSeries
Subject: MOVE vs. EVAL

Is there any real difference between the keywords MOVE and EVAL? If so, 
would someone mind explaining them to me.

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