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Wow Larry, what a post. Glad somebody else found the topic as interesting as I did. A quick glance through the post seems to confirm what I found in my testing, though you went at it from a different angle. Hopefully, I'll get a chance to really look at you post a little later. Thanks, Charles Wilt -- iSeries Systems Administrator / Developer Mitsubishi Electric Automotive America ph: 513-573-4343 fax: 513-398-1121 > -----Original Message----- > From: rpg400-l-bounces@xxxxxxxxxxxx > [mailto:rpg400-l-bounces@xxxxxxxxxxxx] On Behalf Of Larry Ducie > Sent: Wednesday, May 10, 2006 1:32 AM > To: rpg400-l@xxxxxxxxxxxx > Subject: RE: CONST Parameter passing, varying and *varsize > > Hi Chaps, > > I have been following this discussion with great interest. To > satisfy my own > curiosity I created a test program (below is the code). This > performs a > series of calls to a couple of procedures, each with a > selection of 10-alpha > parameters defined. The procedures call CEEDOD for each > parameter, to see > what is actually passed. A comparison of these values to the > values declared > in the prototype are listed in a summary table below the code: > > (Apologies if this doesn't format correctly) > ************************************************************** > ******************************** > d proc1 pr opdesc > d parm1 10a const options(*varsize) > d parm2 10a const > d parm3 10a options(*varsize) > d parm4 10a const options(*varsize) varying > d parm5 10a const varying > d parm6 10a options(*varsize) varying > > d proc2 pr opdesc > d parm1 10a const options(*varsize) varying > d parm2 10a const varying > d parm3 10a const options(*varsize) > d parm4 10a const > > d CEEDOD pr > d posn 10i 0 const > d desctype 10i 0 > d datatype 10i 0 > d descinf1 10i 0 > > d descinf2 10i 0 > d datalen 10i 0 > d feedback 12a options(*omit) > ************************************************************** > ******************************** > > d parmvalue1 s 1a inz('1') > d parmvalue10 s 10a inz('1234567890') > d parmvalue100 s 100a inz('1234567890>>>') > > d parmvalue1v s 1a inz('1') varying > d parmvalue10v s 10a inz('1234567890') varying > d parmvalue100v s 100a inz('1234567890>>>') varying > > d desc s 10i 0 > d data s 10i 0 > d inf1 s 10i 0 > d inf2 s 10i 0 > d len s 10i 0 > ************************************************************** > ******************************** > /free > > // Procedure proc1 is called with 6 parameters: > // The first three are fixed length strings. > // The next three are varying length strings. > > // In all cases, the parameters are passed using the > following prototype: > // 10a const options(*varsize) > // 10a const > // 10a options(*varsize) > // 10a const options(*varsize) varying > // 10a const varying > // 10a options(*varsize) varying > > // Pass 1-alpha strings... > dsply (' '); > dsply ('Proc1 called with 1-alpha strings'); > proc1(parmvalue1 :parmvalue1 :parmvalue1 > :parmvalue1v :parmvalue1v :parmvalue1v); > > // Pass 10-alpha strings... > dsply (' '); > dsply ('Proc1 called with 10-alpha strings'); > proc1(parmvalue10 :parmvalue10 :parmvalue10 > :parmvalue10v :parmvalue10v :parmvalue10v); > > // Pass 100-alpha strings... > dsply (' '); > dsply ('Proc1 called with 100-alpha strings'); > proc1(parmvalue100 :parmvalue100 :parmvalue100 > :parmvalue100v :parmvalue100v :parmvalue100v); > > // Procedure proc2 is called with 4 parameters: > // The first two are varying length strings. > // The next two are fixed length strings. > > // In all cases, the parameters are passed using the > following prototype: > // 10a const options(*varsize) varying > // 10a const varying > // 10a const options(*varsize) > // 10a const > > // Pass 1-alpha strings... > dsply (' '); > dsply ('Proc2 called with 1-alpha strings'); > proc2(parmvalue1 :parmvalue1 :parmvalue1v :parmvalue1v); > > // Pass 10-alpha strings... > dsply (' '); > dsply ('Proc2 called with 10-alpha strings'); > proc2(parmvalue10 :parmvalue10 :parmvalue10v :parmvalue10v); > > // Pass 100-alpha strings... > dsply (' '); > dsply ('Proc2 called with 100-alpha strings'); > proc2(parmvalue100 :parmvalue100 :parmvalue100v :parmvalue100v); > > *inLR = *on; > return; > > /end-free > ************************************************************** > ******************************** > p proc1 b > ************************************************************** > ******************************** > d proc1 pi opdesc > d parm1 10a const options(*varsize) > d parm2 10a const > d parm3 10a options(*varsize) > d parm4 10a const options(*varsize) varying > d parm5 10a const varying > d parm6 10a options(*varsize) varying > ************************************************************** > ******************************** > /free > > monitor; > > CEEDOD(1 :desc :data :inf1 :inf2 :len :*OMIT); > dsply ('variable 1 value = ' + parm1); > dsply ('variable 1 length = ' + %char(len)); > > CEEDOD(2 :desc :data :inf1 :inf2 :len :*OMIT); > dsply ('variable 2 value = ' + parm2); > dsply ('variable 2 length = ' + %char(len)); > > CEEDOD(3 :desc :data :inf1 :inf2 :len :*OMIT); > dsply ('variable 3 value = ' + parm3); > dsply ('variable 3 length = ' + %char(len)); > > CEEDOD(4 :desc :data :inf1 :inf2 :len :*OMIT); > dsply ('variable 4 value = ' + parm4); > dsply ('variable 4 length = ' + %char(len)); > > CEEDOD(5 :desc :data :inf1 :inf2 :len :*OMIT); > dsply ('variable 5 value = ' + parm5); > dsply ('variable 5 length = ' + %char(len)); > > CEEDOD(6 :desc :data :inf1 :inf2 :len :*OMIT); > dsply ('variable 6 value = ' + parm6); > dsply ('variable 6 length = ' + %char(len)); > > on-error *program; > dsply ('parameter error calling proc1'); > endmon; > > return; > > /end-free > ************************************************************** > ******************************** > p proc1 e > ************************************************************** > ******************************** > > ************************************************************** > ******************************** > p proc2 b > ************************************************************** > ******************************** > d proc2 pi opdesc > d parm1 10a const options(*varsize) varying > d parm2 10a const varying > d parm3 10a const options(*varsize) > d parm4 10a const > ************************************************************** > ******************************** > /free > > monitor; > > CEEDOD(1 :desc :data :inf1 :inf2 :len :*OMIT); > dsply ('variable 1 value = ' + parm1); > dsply ('variable 1 length = ' + %char(len)); > > CEEDOD(2 :desc :data :inf1 :inf2 :len :*OMIT); > dsply ('variable 2 value = ' + parm2); > dsply ('variable 2 length = ' + %char(len)); > > CEEDOD(3 :desc :data :inf1 :inf2 :len :*OMIT); > dsply ('variable 3 value = ' + parm3); > dsply ('variable 3 length = ' + %char(len)); > > CEEDOD(4 :desc :data :inf1 :inf2 :len :*OMIT); > dsply ('variable 4 value = ' + parm4); > dsply ('variable 4 length = ' + %char(len)); > > on-error *program; > dsply ('parameter error calling proc2'); > endmon; > > return; > > /end-free > ************************************************************** > ******************************** > p proc2 e > ************************************************************** > ******************************** > > > Results: > > Prototype definition Passed variable Op Desc > parameter type and length > 10a const options(*varsize) 1a 1a > 10a const 1a 10a > 10a options(*varsize) 1a 1a > 10a const options(*varsize) varying 1a varying > 1a varying > 10a const varying 1a varying > 10a varying > 10a options(*varsize) varying 1a varying > 1a varying > 10a const options(*varsize) varying 1a > 1a varying > 10a const varying 1a > 10a varying > 10a const options(*varsize) 1a varying 1a > 10a const 1a varying 10a > > 10a const options(*varsize) 10a 10a > 10a const 10a 10a > 10a options(*varsize) 10a 10a > 10a const options(*varsize) varying 10a varying > 10a varying > 10a const varying 10a varying > 10a varying > 10a options(*varsize) varying 10a varying > 10a varying > 10a const options(*varsize) varying 10a > 10a varying > 10a const varying 10a > 10a varying > 10a const options(*varsize) 10a varying 10a > 10a const 10a varying 10a > > 10a const options(*varsize) 100a 10a > 10a const 100a 10a > 10a options(*varsize) 100a 100a > 10a const options(*varsize) varying 100a varying > 10a varying > 10a const varying 100a varying > 10a varying > 10a options(*varsize) varying 100a varying > 100a varying *** > 10a const options(*varsize) varying 100a > 10a varying > 10a const varying 100a > 10a varying > 10a const options(*varsize) 100a varying 10a > 10a const 100a varying 10a > > Notes: > 1) When const is specified the received variable has a length > which never > exceeds the length set on the prototype definition. > 2) When using const and not options(*varsize), if the passed > fixed-length > parameter is smaller than that defined on the prototype, it > is padded with > blanks. > 3) When using const and options(*varsize), if the passed fixed-length > parameter is smaller than that defined on the prototype, it > is not padded > with blanks. > 4) In cases 2) and 3) for received varying-length variables > the length > portion is set appropriately - padding is not required. > 5) When options(*varsize) is specified the received variable > has a length > equal to that passed by the caller - this can cause problems with > varying-length variables. See 6) below. > 6) When varying is specified, with options(*varsize) and > without const, > referencing the variable will cause a runtime error if the > actual length > passed exceeds the prototype definition. > 7) When passing a fixed-length string using a varying-length > prototype > definition the following must be considered: > i) You MUST use const - otherwise a parameter mismatch > will be thrown and > the module will not compile. > ii) Because of the requirement to use const, even when specifying > options(*varsize), any strings passed which are longer than > the prototype > definition will be truncated to the length set by the > prototype definition. > iii) For passed strings with a length exceeding the > prototype definition, > the length portion of the received variable will be set to > the truncated > length. > 8) When passing a varying-length string using a fixed-length > ptototype > definition the following must be considered: > i) You MUST use const - otherwise a parameter mismatch > will be thrown and > the module will not compile. > ii) Because of the requirement to use const, even when specifying > options(*varsize), any strings passed which are longer than > the prototype > definition will be truncated to the length set by the > prototype definition. > > ** In all cases any reference to parameter length is the > length retrieved > from CEEDOD, not the declared prototype length. > > *** Any reference to the variable causes runtime error. This > is due to it > having an invalid length portion. > > > Of course, this does not directly address the question of > temporary variable > use, but it may give an indication of scenarios where > temporary variables > would likely get used. These resulta, or my conclusions may > be incorrect, I > will happily have them corrected for the benefit of the archive. > > > Cheers > > Larry Ducie > > > -- > This is the RPG programming on the AS400 / iSeries (RPG400-L) > mailing list > To post a message email: RPG400-L@xxxxxxxxxxxx > To subscribe, unsubscribe, or change list options, > visit: http://lists.midrange.com/mailman/listinfo/rpg400-l > or email: RPG400-L-request@xxxxxxxxxxxx > Before posting, please take a moment to review the archives > at http://archive.midrange.com/rpg400-l. > >
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