Re: Procedure parameters

Mike,

The ValFldNum procedure receives a pointer to a memory location and, 
because the procedure interface says this points to a 20A field, 
interprets 20 bytes as a 20A field. OPTIONS(*VARSIZE) tells the compiler 
not to worry when you pass a field of different length, so you get away 
with passing a 5A field. What is missing is a way for the ValFldNum to 
find out the actual length of the parameter. 

Possibilities:
- Use an extra parameter to pass the length ('the API way');
- Use a VARYING parameter; then the parameter itself contains the actual 
length;
- Use operational descriptors; then the procedure can use an API to 
determine the actual length.

For performance choose the extra parameter; for a clean interface use a 
VARYING parameter in combination with CONST.

Joep Beckeringh






"Mike Pantzopoulos - (H/O)" <mpantzopoulos@xxxxxxxxxxxxxxxx>
Sent by: rpg400-l-bounces@xxxxxxxxxxxx
07-09-2005 06:04
Please respond to RPG programming on the AS400 / iSeries
 
        To:     <rpg400-l@xxxxxxxxxxxx>
        cc: 
        Fax to: 
        Subject:        Procedure parameters


I have an EDI aoplication which needs to validate that certain character
fields are actually numeric.

These character fields can all be different lengths and I had some
problems in using the fields directly as parameters until I realized
that the options(*varsize) can be used witht the parameter to tell the
compiler to ignore size differences on the invocation.

I now have a program which invokes a procedure to manage validation that
a character field is in fact numeric.
The prototype is:

     D ValFldNum       PI             1N
     D FldNme                          14A   CONST
     D FldVal                            20A   Options(*Varsize)

I pass in the field name so that I can generate a message indicating
which field is in error if necessary.


This procedure calls another procedure which determines if the character
field is actually a valid numeric:

     D FldIsNum        PR             1N 
     D  String                            20A   Options(*Varsize) 

A typical call from the top level is:

     C                   CALLP     ValFldNum('HDR_KSAID': HDR_KSAID)

Where HDR_KSAID is 5 bytes long.

And the ValFldNum invokes:

    C                     IF        FldIsNum(FldVal)

I expected that the field used by the FldIsNum procedure would contain
just the 5 bytes, but when I debug it, I actually get the 20 bytes
starting from the start of the HDR_KSAID field.

I'm sure I've seen a BIF which returns the actual length of the
parameter at execution time but I can't seem to remember/find it.

Am I completely lost? Or is there a simple answer?

Thanks

Mike Pantzopoulos



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