Re: Please read: Pointer not set for location .....

Date: Thu, 31 May 2001 09:27:11 -0400
From: "Slava Zharichenko" <Slava.Zharichenko@exel.com>
Subject: Please read: Pointer not set for location .....

> ...
>and change return variable definition from 1 *char to 16 *char even RPG
>procedure returns only 1 *char.
>
>Now it works , first byte contain return value and other 15 some none
>displayable characters.
>
>Can anybody explain it?

Slava, you should be sure to use %sst in your CL, so you only use the
first byte of the returned value.  By the way, you don't need to define
it as 16 bytes; you just need more than 1.

What's happening is that RPG and CL disagree on how to handle 1 byte
return values.  CL and C handle them one way; RPG and COBOL handle them
another (CL and C are "right" because they were first, but RPG and COBOL
can't change because of all the existing programs that expect it to be
done "the RPG way").  What's actually happening is that C and CL think
of 1A (at least in return values) as a 1-byte unsigned integer, while
RPG and COBOL think of it as a 1-byte structure (string); unfortunately,
structures are returned using a sort of pointer mechanism under the covers.

In V5R1, you can code a special first parameter for EXTPROC to avoid this
problem.

D rpgproc       pr        1a EXTPROC(*CL : 'RPGPROC')
D calledByC     pr        1a EXTPROC(*CWIDEN : 'calledByC')

Use *CL when you're called by CL; use *CWIDEN (or *CNOWIDEN if the C
is not widening parameters) when calling C or being called by C.  *CWIDEN
avoids problems with several parameter types passed by value (char(1a),
short (5i 0), unsigned short (5u 0), float(4f), wchar (1C or 1G)).

Barbara Morris

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