RE: RE: RPG/400 pgm strange behavior

Thanks for kicking my brain into gear.  The magic phrase here is "command
line".  If, on a command line, you type:

call x parm(a b)

then the command analyzer will

allocate two 32-byte fields - lets call them p1 and p2,
create a space pointer to p1 and a space pointer to p2 - lets call them @p1
and @p2
the copy the value a into p1 and the value b into p2,
then call program x passing @p1 and @p2

If you type

call x parm('a' and 'b')

Then everything is the same except the field allocation.  In this instance,
the fields will be one byte long.

If you type:

call x parm(1 2)

then the allocations will be for a packed number 15 digits with 5 decimals.
I never discovered a way to change the allocation for numbers.

If you type:

call x parm('a                                        ')

(that should be the letter a followed by 40 blanks enclosed in single
quotes) the command analyzer will allocate a field of 41 bytes, copy the
letter a into the first position, then call program X passing a space
pointer to the first character of the 41 byte field.

In other words, the default length for a character value when calling from
the command line is 32 bytes.  You can make the actual length shorter by
using a shorter quoted character string.  You can make it longer by using a
longer quoted character string or by passing a longer unquoted string if
that string contains no blanks or stop characters (such as a single quote or
double quote).  If you use a command, the command analyzer can be instructed
to tell the called program the length of the parameter value.

When calling from program to program, the parameters are usually passed as
space pointers to the first byte in the parameter.  It is up to the programs
to agree on the type and length of the parameters, data type semantics and
so forth.  A good development process using prototypes can assist the
programs to use the same type and length but it is not a guarantee - an
unruly program can still do the wrong thing and break something.

I haven't had to face this problem for some time so this explanation might
be obsolete.

Richard Jackson
mailto:richardjackson@richardjackson.net
www.richardjacksonltd.com
Voice: 1 (303) 808-8058
Fax:   1 (303) 663-4325

-----Original Message-----
From: owner-rpg400-l@midrange.com [mailto:owner-rpg400-l@midrange.com]On
Behalf Of Marcin Sagan
Sent: Thursday, July 13, 2000 1:36 AM
To: RPG400-L@midrange.com
Subject: Odp: RE: RPG/400 pgm strange behaviour


Danny

I couldn't repeat this bug when program to program was called no mater what
kind of program or call I used but maybe I missed something.
It looks like command line parameter passing problem.
So you don't need to worry about calling from program.

Best regards


Marcin Sagan

!
   !

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