Re: Using Pointers

[Pete Hall <peteh@xxxxxxxxxx>]

At 09:43 12/17/1998 -0500, Michael Franchino wrote:
>this.. I have created a procedure that accepts parameters. This 
>procedure will fetch a record in a file by key. This file contains
>3 fields of 256 bytes (Flat file structure). After finding the
>record I asked for, I need to load that field data into a Data Structure 
>in my main program. The data structure breaks out all of the fields
>for me. The problem is that depending upon what record I fetch from
>a file points to a different data structure. 
>
>I thought that I could use a pointer to point to a data structure and
>pass that to my procedure and have the fields read in moved to that
>pointer. My problem is that I don't uderstand how to use RPG/IV pointers
>that well and am really confused. My only other choice is to pass back
>the data in a field and have the main program move it into a data 
>structure, but I would prefer to have my procedure do it.

Here are a couple of possibilities:

  D DS1       DS 
  D  Field1 
  D  Field2
  D  Field3

  C                   eval      DS1 = Proc1(aa:bb:cc)

 or:

  D @DS1      S               *          Inz(*NULL)
  D DS1       DS                         Based(@DS1)
  D  Field1 
  D  Field2
  D  Field3

  C                   callp     Proc1(aa:bb:cc:dd)
  C                   eval      @DS1 = %Addr(dd)

In reality, what you are passing when you pass parameters by reference, is
a pointer.
Pete Hall
peteh@inwave.com
http://www.inwave.com/~peteh
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