Re: C macros

Frank,
I think that your reference to K&R is a joke.
K&R book is a book for learning language. It is not for learning style.
They used "forever" as an example what CAN BE done using #define but they never said that it SHOULD BE done.
Feel the difference.

I personally hate this sort of macros because they make program unreadable for others - exactly what Barbara told you earlier.
So: think of the people who will read your code, use clear constructions!

Next thing - do not overestimate the meaning of programming style.
I am reading the thread and sometimes do not agree.

Mark advises to format this way:
    if (f EQ NULL) {
       printf("can't open file %s\n", PFILENAME);
       exit(rc);
       }

I personally prefer to write it another way:
if (f == NULL) 
{
	printf("can't open file %s\n", PFILENAME) ;
      exit(rc) ;
}

But there was one sentence in Mark's mail that impressed me really much an with which I agree 100%.
This is the last sentence about the style:

"Whatever you decide to do, strive for consistency."

Now on ability to interprete code with macros. Don't be so sure.
There are even contests on who will write the most difficult for understanding C code - google it and try to understand.

I once had a collegue who was a big fan of macros.
Here's a part of his real code:
-----------------------------------------------------------------------
#define readacc(a) ( rfb =_Rreadk( sc20lf, &buf, sizeof( buf ), ( a )\
, gfcus, 6 ))                                                         
#define bytes ( rfb->num_bytes )                                      
#define buflen ( sizeof( buf ))                                       
  int both = 0 ;                                                      
                                                                      
  readacc ( __KEY_EQ );                                               
  for ( ; ( bytes == buflen ) && both < 2 ; readacc ( __KEY_NEXTEQ ))
-----------------------------------------------------------------------
It was a little too much for me....

Jevgeni.


-----Original Message-----
From: c400-l-bounces-Zwy7GipZuJhWk0Htik3J/[email protected] [mailto:c400-l-bounces-Zwy7GipZuJhWk0Htik3J/[email protected]] On Behalf Of Frank Kolmann
Sent: Friday, April 04, 2014 11:24 AM
To: c400-l
Subject: [C400-L] C macros

Hi Barbara



Thank you for your comments. I am happy to start a discussion on macros.

Please understand I value and appreciate your comments.

Couple of points.



I found the 'forever' macro in this book. pp97



                The C programming Language

                By Brian W. Kernighan and Dennis M. Ritchie.

                Published by Prentice-Hall in 1988

                ISBN 0-13-110362-8 (paperback)

                ISBN 0-13-110370-9

--  exerpt --

                Any name may be defined with any replacement text. For example

                #define forever for (;;) /* infinite loop */

                defines a new word, forever, for an infinite loop.



Do you mean to say that the C gods K&R themselves published weird code?



Also if C programmers cannot cope with macros does not that imply they

are not truly C programmers.



Why does C have the ability to have such marco substitution if it is

not to be used.

Particularly if it helps avoid a potential bug that the compiler

does not report and only manifests at execution time (= for ==).



I believe I will have no problem interpreting the standard C

code or other C code with macros.



Frank





>*Subject: Re: First C Program

> *From: Barbara Morris <bmorris@xxxxxxxxxx>

> *Date: Thu, 03 Apr 2014 13:42:13 -0400

>

>Hi Frank, I have been thinking about the use of macros such as

>EQ, forever, NE etc, and I think you are doing yourself a disservice

>by using these macros as a beginner C programmer. Here are some of the
reasons:

>

>You will find it less easy to read "normal" C code if you don't get

>used to seeing *and quickly interpreting* things like != == for(;;)

>

>You will find it more difficult to incorporate code that you find on 
>the
web.

>You will have to either change all the == and != to use your macros,

>or perhaps even worse, you will have a mixture of EQ and ==.

>

>You will not be able to post snippets of code to forums without

>replacing your macros. I wouldn't post weird code like that to any 
>forum

>even with an explanation for what the macros mean.

>The discussion would almost certainly be more about the use of the 
>macros than about whatever question you were trying to ask.
--
This is the Bare Metal Programming IBM i (AS/400 and iSeries) (C400-L) mailing list To post a message email: C400-L-Zwy7GipZuJhWk0Htik3J/[email protected] To subscribe, unsubscribe, or change list options,
visit: http://lists.midrange.com/mailman/listinfo/c400-l
or email: C400-L-request-Zwy7GipZuJhWk0Htik3J/[email protected]
Before posting, please take a moment to review the archives at http://archive.midrange.com/c400-l.

-- 
This is the Bare Metal Programming IBM i (AS/400 and iSeries) (C400-L) mailing list
To post a message email: C400-L-Zwy7GipZuJhWk0Htik3J/[email protected]
To subscribe, unsubscribe, or change list options,
visit: http://lists.midrange.com/mailman/listinfo/c400-l
or email: C400-L-request-Zwy7GipZuJhWk0Htik3J/[email protected]
Before posting, please take a moment to review the archives
at http://archive.midrange.com/c400-l.