Re: Operational descriptors

["Simon Coulter" <shc@xxxxxxxxxxxxxxxxx>]

Œ
Hello Peter,

You wrote:
>Thanks a bunch, my problem was that I did not specify CONST.
>This appears to mean that it cannot be called using CALLB.

No, all the CEE APIs can be invoked via CALLB.  The CONST just makes it 
easier to use literals and constant values.  The main trick is in the 
OPTIONS(*VARSIZE) which causes the actual length of the parameter to be 
passed thus the API can determine the data type and length.  The API defines 
the timestamp and picture string as a VSTRING which supports VARCHAR (with 
both 2-byte and 4-byte lengths), a fixed-length string (what I used in my 
example), or a null-terminated string.  I don't think RPG IV can handle all 
those different types on a single prototype.  The interesting thing is that 
the C-prototype defines a structure much like the one I used, however I don't 
see how using a structure with a length attribute will appear to the API as a 
true VARCHAR.  Still, it works with fixed length strings and it probably 
works with real VARCHARs so that's fine.

Here is an example (that works) using CALLB:

H DFTACTGRP(*NO)                                                     
                                                                     
D aTimestamp      S             23    INZ('2001-07-26 14:00:23.123') 
D aPictureString  S             23    INZ('YYYY-MM-DD HH:MI:SS.999') 
D theNbrOfSecs    S              8F                                  
                                                                     
C                   CALLB(D)  'CEESECS'                              
C                   PARM                    aTimestamp               
C                   PARM                    aPictureString           
C                   PARM                    theNbrOfSecs             
C                   PARM                    *OMIT                    
                                                                     
C     theNbrOfSecs  DSPLY                                            
                                                                     
C                   SETON                                        LR  
C                   RETURN                                           

>Incidentally, another issue arises when attempting to use the converse API
>CEEDATM to reformat the seconds back to a different picture string. Since
>the picture string doesn't use the % syntax
>that the C runtime time format functions use, then it's not possible to
>include a string like GMT in the picture because it contains one of the
>formatting codes (M). This means I'll either have to insert it afterwards or
>revert using the C functions.

Not really an issue, just a different design goal of the API.  It appears to 
default to returning a timestamp in the default format for the job based on 
the country code.  Simply concatenate the 'GMT' string to the returned 
string.

Regards,
Simon Coulter.

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