Re: First C program

The GENCSRC facility allows you to generate C/C++ header files for database
files. That is the mechanism used in the C++ language. You can find a
comparison between #pragma mapinc and GENCSRC in Appendix A of the ILE C/C+
+ Programmer's Guide. Here is a link to the 6.1 version of that document:
http://pic.dhe.ibm.com/infocenter/iseries/v6r1m0/topic/rzaha/sc092712.pdf

Aaron


c400-l-bounces@xxxxxxxxxxxx wrote on 04/03/2014 10:39:56 AM:

From: Steve Richter <stephenrichter@xxxxxxxxx>
To: "Bare Metal Programming IBM i (AS/400 and iSeries)" <c400-
l@xxxxxxxxxxxx>,
Date: 04/03/2014 10:40 AM
Subject: Re: [C400-L] First C program
Sent by: c400-l-bounces@xxxxxxxxxxxx

I notice that C++ does not support the #pragma mapinc statement:

#pragma mapinc("ddhpf","*libl/REL(*ALL)","input"," ",,"")
#include "ddhpf"

I was going to suggest compiling as C++ and using classes to reduce the
complexity of the code. But the CRTCPPMOD command does not support

#pragma

mapinc ?

"QGPL/QRPGLESRC(CSAMPLEC)", line 22.10: CZP0836(30) The #include file
"ddhpf" is not found.

-Steve



On Thu, Apr 3, 2014 at 6:39 AM, Frank Kolmann <fkolmann@xxxxxxxxx> wrote:

Hi Jevgeni



Thank you. You make good points.

That is a good way of trapping the == issue.

I will follow Barbaras advice in the coding of the if.



I like the way you use the #define for the type defs.

It does make the code clearer, I will use that sytle.



Frank

*Subject: Re: First C program

*From: Jevgeni Astanovski <Jevgeni.Astanovski@xxxxxxxxxxxxx>

*Date: Wed, 2 Apr 2014 07:54:34 +0000

Yes. Barbara mentioned the define and I haven't...

Definitely there are lots of this sort of advises to avoid =/==

possible

mistake.

I've never saw the one you referred.

However some use another technique:

Instead of writing

if ((pf = _Ropen(PFILENAME, "rr")) == NULL)

they write

if (NULL == (pf = _Ropen(PFILENAME, "rr")))

In this case if you make a mistake and write

if (NULL = (pf = _Ropen(PFILENAME, "rr")))

you will immediately get a syntax error.

....

On the second issue - this is purely a question of how readable is

your

program.

My personal practice is to use "explicit" way of defining types. For

example:

#pragma mapinc("dspf", "*LIBL/Y80ALD(ADDCHRG)", "both", "_P", "Y80",

"Y80")

#include "dspf"

#define INPUT_T Y80_ADDCHRG_i_t

#define OUTPUT_T Y80_ADDCHRG_o_t

in this case it is (more) clear where these types are derived from....

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