Re: First C program

One more thing.
You write:
		memcpy (sfrcd.S01FUNC  , "          ", 2  );
            memcpy (sfrcd.S01APFILE, "          ", 10 );
            memcpy (sfrcd.S01APLIB , "          ", 10 );
            memcpy (sfrcd.S01APACCP, "          ", 1  );
            memcpy (sfrcd.S01APUNIQ, "          ", 1  );
            memcpy (sfrcd.S01APSELO, "          ", 1  );
            memcpy (sfrcd.S01APFTYP, "          ", 1  );
            memcpy (sfrcd.S01APJOIN, "          ", 1  );
            memcpy (sfrcd.S01APKEYO, "          ", 1  );
            memcpy (sfrcd.S01APKSEQ, pfrcd.APKSEQ, 1  );
            memcpy (sfrcd.S01APKSIN, pfrcd.APKSIN, 1  );
            memcpy (sfrcd.S01APKEYF, pfrcd.APKEYF, 10 );

My advise is to do it another way:
	memset(&sfrcd, ' ', sizeof(sfrcd)) ;
      memcpy (sfrcd.S01APKSEQ, pfrcd.APKSEQ, 1  );
      memcpy (sfrcd.S01APKSIN, pfrcd.APKSIN, 1  );
      memcpy (sfrcd.S01APKEYF, pfrcd.APKEYF, 10 );

C differs from other languages - it does not initialize variables on declarations in general, and structures - in particular.
So by setting full structure to spaces and then assigning/initializing only specific fields you make your program at least shorter. But also more reliable.
Of course you must take care of numeric fields - you have to explicitly assign valid numeric values to them before accessing.


-----Original Message-----
From: c400-l-bounces-Zwy7GipZuJhWk0Htik3J/[email protected] [mailto:c400-l-bounces-Zwy7GipZuJhWk0Htik3J/[email protected]] On Behalf Of Frank Kolmann
Sent: Thursday, April 03, 2014 1:39 PM
To: c400-l
Subject: [C400-L] First C program

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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