• The Four Hundred
  • Subscribe
  • Media Kit
  • Contributors
  • About Us
  • Contact
Menu
  • The Four Hundred
  • Subscribe
  • Media Kit
  • Contributors
  • About Us
  • Contact
  • Can a Function Return More Than One Value?

    January 20, 2010 Hey, Ted

    Is it possible for an RPG subprocedure to return more than one value? (I assume it isn’t; the RETURN opcode only allows for one argument.) I want to write a function subprocedure that will return a data structure of information taken from various database files. However, the subprocedure will also need to return a status code to indicate whether or not the I/O was successful. Do you have any suggestions?

    –Travis

    What you want to do is something like this:

    eval (MyDataStructure: Status) = GetData (KeyValue)
    

    No, that won’t work. But I can show you two other ways that will.

    Let’s set up a situation like the one you’re describing. Suppose a service program needs a subprocedure GetCustInfo to provide customer data to its caller. It also needs to tell the caller whether the data retrieval succeeded or not.

    One way to handle this is to return both values in parameters. GetCustInfo uses the values in Company and Customer to retrieve the data, then modifies CustRec and FileStatus accordingly. The subprocedure behaves as a subroutine, not as a function, and any RETURN opcodes in the subprocedure do not have arguments.

    P GetCustInfo     b
    D                 pi
    D  inCompany                     3p 0 value
    D  inCustomer                    5p 0 value
    D  ouCustRec                          likeds(CustRec)
    D  ouStatus                      1p 0
    D
    D CustKey         ds                  likerec(Customer: *key)
     /free
         CustKey.CompanyNo = inCompany;
         CustKey.CustomerNo = inCustomer;
         monitor;
            chain %kds(CustKey) Customer ouCustRec;
            if %found();
               ouStatus = *zero;
            else;
               ouStatus = 1;
            endif;
         on-error;
            ouStatus = 2;
         endmon;
         return;
     /end-free
    P                 e
    

    Use CALLP to invoke GetCustInfo.

    D Company         s              3p 0
    D Customer        s              5p 0
    D FileStatus      s              1p 0
    D CustRec         ds                  likerec(Customer: *input) inz
     /free
       callp GetCustInfo (Company: Customer: CustRec: FileStatus);
    

    If you prefer, you can use a function subprocedure that modifies a parameter. The function passes two values–a status code and a data structure–to the caller through two mechanisms, so which mechanism should you pair with which value?

    I prefer to pass data through the modified parameter and let the function return the status.

    P GetCustInfo     b
    D                 pi             1p 0
    D  inCompany                     3p 0 value
    D  inCustomer                    5p 0 value
    D  ouCustRec                          likeds(CustRec)
    D
    D CustKey         ds                  likerec(Customer: *key)
     /free
         CustKey.CompanyNo = inCompany;
         CustKey.CustomerNo = inCustomer;
         monitor;
            chain %kds(CustKey) Customer ouCustRec;
            if %found();
               return *zero;
            else;
               return 1;
            endif;
         on-error;
            return 2;
         endmon;
     /end-free
    P                 e
    

    For one thing, status codes tend to be small and data structures tend to be bigger. But an even greater advantage is that the function calls work well with control structures. For instance:

    dow GetCustInfo(Company: Customer: CustRec) = *zero;
    

    As a rule, functions do not modify parameters. After all, can you think of an RPG built-in function that modifies an argument? But that’s not to say that a function should never modify a parameter. Your application is a good example of that.

    –Ted



                         Post this story to del.icio.us
                   Post this story to Digg
        Post this story to Slashdot

    Share this:

    • Reddit
    • Facebook
    • LinkedIn
    • Twitter
    • Email

    Tags:

    Sponsored by
    VISUAL LANSA 16 WEBINAR

    Trying to balance stability and agility in your IBM i environment?

    Join this webinar and explore Visual LANSA 16 – our enhanced professional low-code platform designed to help organizations running on IBM i evolve seamlessly for what’s next.

    🎙️VISUAL LANSA 16 WEBINAR

    Break Monolithic IBM i Applications and Unlock New Value

    Explore modernization without rewriting. Decouple monolithic applications and extend their value through integration with modern services, web frameworks, and cloud technologies.

    🗓️ July 10, 2025

    ⏰ 9 AM – 10 AM CDT (4 PM to 5 PM CEST)

    See the webinar schedule in your time zone

    Register to join the webinar now

    What to Expect

    • Get to know Visual LANSA 16, its core features, latest enhancements, and use cases
    • Understand how you can transition to a MACH-aligned architecture to enable faster innovation
    • Discover native REST APIs, WebView2 support, cloud-ready Azure licensing, and more to help transform and scale your IBM i applications

    Read more about V16 here.

    Share this:

    • Reddit
    • Facebook
    • LinkedIn
    • Twitter
    • Email

    Sponsored Links

    PowerTech:  Strengthen your security. Get a FREE Compliance Assessment today
    Profound Logic Software:  FREE Webinar, Jan 27. Learn how to integrate your i apps and save big
    COMMON:  Join us at the annual 2010 conference, May 3 - 6, in Orlando, Florida

    IT Jungle Store Top Book Picks

    Easy Steps to Internet Programming for AS/400, iSeries, and System i: List Price, $49.95
    The iSeries Express Web Implementer's Guide: List Price, $49.95
    The System i RPG & RPG IV Tutorial and Lab Exercises: List Price, $59.95
    The System i Pocket RPG & RPG IV Guide: List Price, $69.95
    The iSeries Pocket Database Guide: List Price, $59.00
    The iSeries Pocket SQL Guide: List Price, $59.00
    The iSeries Pocket Query Guide: List Price, $49.00
    The iSeries Pocket WebFacing Primer: List Price, $39.00
    Migrating to WebSphere Express for iSeries: List Price, $49.00
    Getting Started With WebSphere Development Studio Client for iSeries: List Price, $89.00
    Getting Started with WebSphere Express for iSeries: List Price, $49.00
    Can the AS/400 Survive IBM?: List Price, $49.00
    Chip Wars: List Price, $29.95

    Hybrid Cloud Adoption Rates to Exceed 60 Percent This Year, EDC Says IBM Preps Power7 Launch For February

    Leave a Reply Cancel reply

Volume 10, Number 3 -- January 20, 2010
THIS ISSUE SPONSORED BY:

SEQUEL Software
WorksRight Software
COMMON

Table of Contents

  • Run SQL Scripts: Use Temporary JDBC Settings
  • Can a Function Return More Than One Value?
  • Admin Alert: Erasing i5/OS Disk for Fun and Compliance

Content archive

  • The Four Hundred
  • Four Hundred Stuff
  • Four Hundred Guru

Recent Posts

  • Liam Allan Shares What’s Coming Next With Code For IBM i
  • From Stable To Scalable: Visual LANSA 16 Powers IBM i Growth – Launching July 8
  • VS Code Will Be The Heart Of The Modern IBM i Platform
  • The AS/400: A 37-Year-Old Dog That Loves To Learn New Tricks
  • IBM i PTF Guide, Volume 27, Number 25
  • Meet The Next Gen Of IBMers Helping To Build IBM i
  • Looks Like IBM Is Building A Linux-Like PASE For IBM i After All
  • Will Independent IBM i Clouds Survive PowerVS?
  • Now, IBM Is Jacking Up Hardware Maintenance Prices
  • IBM i PTF Guide, Volume 27, Number 24

Subscribe

To get news from IT Jungle sent to your inbox every week, subscribe to our newsletter.

Pages

  • About Us
  • Contact
  • Contributors
  • Four Hundred Monitor
  • IBM i PTF Guide
  • Media Kit
  • Subscribe

Search

Copyright © 2025 IT Jungle