Prototyping printf()

["Simon Coulter" <shc@xxxxxxxxxxxxxxxxx>]

Hello all,

Now here's an interesting exercise that is rapidly becoming one of futility.

printf() is a C function that expects a format string followed by zero or more 
substitution values.  The substitution arguments can be any of C's supported 
data types 
and are passed by value.  Prototypng it for known data types is easy but the 
real point 
is to create a single definition that can handle all data types.  A sample 
prototype of 
the form:

D printf        PR                      10I 0  EXTPROC('printf')
D  formatString                           *    VALUE OPTIONS(*STRING)
D  arg1                                 10I 0  VALUE OPTIONS(*NOPASS)

will allow dynamic printing like:

C               EVAL    rc=printf('The number is %i ' : anInt)

however if I then want to print a string I need a separate prototype with arg1 
defined 
appropriately.

D printf        PR                      10I 0  EXTPROC('printf')
D  formatString                           *    VALUE OPTIONS(*STRING)
D  arg1                                   *    VALUE OPTIONS(*STRING:*NOPASS)

and then I can:

C               EVAL    rc=printf('The string is %s ' : aString)

and so we go on with additional prototypes for each possible variation of 
substitution 
arguments.

My question (to which I think the answer is NO) is:  Is it possible to define 
an RPG 
prototype describing printf() in its native form?

The difficulty seems to hinge on C's requirement for passing by VALUE and RPGs 
requirement for knowing the data type up front.  The closest I can come to 
allowing RPG 
to accept anything is by using a prototype like:

D printf        PR                      10I 0  EXTPROC('printf')
D  formatString                           *    VALUE OPTIONS(*STRING)
D  arg1                                   *    VALUE OPTIONS(*NOPASS)
D  arg2                                   *    VALUE OPTIONS(*NOPASS)
D  arg3                                   *    VALUE OPTIONS(*NOPASS)
D  arg4                                   *    VALUE OPTIONS(*NOPASS)

which allows RPG to successfully compile statements such as:

C               for     count = 0 to 10 by 2
C               EVAL    rc=printf('%s %i' : %addr(string) : %addr(count) )
C               endfor

When it runs the string is printed successfully but the integer is not because 
it is the 
VALUE of the ADDRESS of the integer that is being passed not the VALUE of the 
integer.  
And that leads us back to a prototype like:

D printf        PR                      10I 0  EXTPROC('printf')
D  formatString                           *    VALUE OPTIONS(*STRING)
D  arg1                                   *    VALUE OPTIONS(*STRING:*NOPASS)
D  arg2                                 10I 0  VALUE OPTIONS(*NOPASS)

Aaaarrrrrggghhhh!!!!

Regards,
Simon Coulter.

«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»
«» FlyByNight Software         AS/400 Technical Specialists       «»
«» Eclipse the competition - run your business on an IBM AS/400.  «»
«»                                                                «»
«» Phone: +61 3 9419 0175      Mobile: +61 0411 091 400           «»
«» Fax:   +61 3 9419 0175      mailto: shc@flybynight.com.au      «»
«»                                                                «»
«» Windoze should not be open at Warp speed.                      «»
«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»
+---
| This is the RPG/400 Mailing List!
| To submit a new message, send your mail to RPG400-L@midrange.com.
| To subscribe to this list send email to RPG400-L-SUB@midrange.com.
| To unsubscribe from this list send email to RPG400-L-UNSUB@midrange.com.
| Questions should be directed to the list owner/operator: david@midrange.com
+---