/Free Control Statements, Part 2

  • Smaller Small Medium Big Bigger
  • Default Helvetica Segoe Georgia Times

DO Stuff: There’s an old programmers’ adage: “Where there’s an IF, there’s a DO,” and darned if it isn’t true.

By David Shirey

Editor's Note: This article is excerpted from chapter 5 of 21st Century RPG: /Free, ILE, and MVC, by David Shirey.

Fortunately, most of what we said for IFs is true for DO loops.

The DO itself has been eliminated from /Free (use FOR). And the DOWGT, DOULT, and others of that ilk are out as well.

What you are left with is simpler and more straightforward: DOW and DOU with a conditional statement. The basic syntax is:

/Free Control Statements, Part 2 - Figure 1

Despite the changes in syntax, these two commands operate the same way they do in positional RPG. That is, the difference is the point in the construct where the decision is made whether to continue with the loop or get out. For the DOW, it is done at the start of the loop; for DOU, it is at the end. In both cases, an ENDDO is required.

As with the IF statement, you can use parentheses and logical operators to write more complex conditions, and you can split them up on multiple lines with a semicolon only at the end-of-line group. For example:

/Free Control Statements, Part 2 - Figure 2

Now, please don’t think that I consider the above example a good example of coding. God help you if you end up ever having to duplicate this kind of logic. In reality, I would break this up into a couple of nested IFs, even though I hate those, too. It’s just an example, not my vision of reality.

/Free Control Statements, Part 2 - Figure 3

FOR Loop

To be honest, this is one that I don’t use that much. But strangely enough, right after I switched to /Free, I used it. Haven’t touched it since. For some reason, using it puts me in a FORTRAN sort of mood and makes me want to drink Harvey Wallbangers. Never really liked them when they were popular, so it’s a good reason to try to avoid the FOR. The Galliano bottles were cool, though.

But, sometimes you need to do a loop a given number of times, and that is what the FOR is there for.

FOR i = 1 to 5;

your indented logic statements; ENDFOR

(There is a syntax error in the above statement. Do you see what it is? Hint: have I mentioned the importance of the semicolon before?)

The From and To limits in the FOR can easily be variables.

One important thing to note is that the FOR statement will automatically update the i value each time the loop ends. So don’t do it yourself. That would be sooooo weird.

/Free Control Statements, Part 2 - Figure 4

Leaving a Loop

Sometimes you may be in an IF statement or a loop and decide you just want to get out. It can be a panic situation. You know, you feel the walls beginning to close in, and the longer the loop runs, the tighter and tighter and tighter ..., well, you get the idea. Often what we do is set a flag and fudge the structure of the loop so that when this flag is set, you can exit. Of course, back in the real olden days we would just do a GOTO and get out, but that was abused and has rightfully been banished by the Great Queen who rules Game of War.

Fortunately, /Free supports the LEAVE and ITER opcodes.

LEAVE will take you to the next statement after the end of the loop you are currently in. It truly gets you out of the loop. Ta-dah!

ITER causes you to jump to the ENDDO (or ENDFOR) and perform the normal checking that is done to see if you should get out or do another iteration. You skip any code within the loop but come back in the loop for another go-round.

In other words, LEAVE does just that: it kicks you out of the loop you are in. ITER bypasses all of the logic between you and the end of the loop, but keeps you in the loop and lets it do the normal checking to see if you should be set free or if you have another ticket to ride.

Both of these opcodes work only if you are in a DOx or FOR loop. You can code it inside a DOx or FOR loop that is in an IF or SELECT statement, but if you just put it in a standalone IF or SELECT, you will get a compile error.


The CALL opcode was not moved over to /Free. Instead, you will use the prototyped call, CALLP.

The format for this is pretty simple:

CALLP DWS0001(parm1:parm2:parm3);

Like the EVAL opcode, however, the CALLP is optional. So you may see the call to a program set up to look more like a BIF statement:


Some people consider this the only civilized way to set up a call, and they use it frequently. For my money, I prefer the first form. The main issue to me is one of clarity. I like having the CALLP there because that is a very clear visual sign that a call is being made. I suppose I should be smart enough to instantly recognize that the other is a call, but I am not. In this case it is obvious, but if I had named my PR spec AP_CREDIT_CHECK instead of DWS0001 (an obvious program name), it might not be quite so clear. And don’t worry, we will talk about what PR specs are later.

It’s a small thing, but to me it sometimes seems that now that we have a version of RPG that is very easy to read and understand, we are taking steps to make it more cryptic. I agree, it looks more Web-like that way, but I would hardly argue that Web languages are easy to read.

But chose whatever form seems best to you. They both work just fine. And, as we shall see later, sometimes you have to use the format without the CALLP.


While we are talking about control logic statements, I want to say just a final word about indenting your code.

Do it!

Indenting is something RPG programmers generally don’t think about too much (since you can’t do it in fixed-format mode). But indenting is probably the single most powerful structure tool a programmer has. Anyone who has struggled to match up IFs and ENDIFs in a big logic section has to appreciate the ability to be able to indent code and so easily see which ENDIF matches up with which IF.

So get in the habit right now. I like to indent four spaces; some people like more or fewer, but they are crazy. The important point is to start to build indenting into your coding style with /Free right away. You won’t regret it.

What Ya Shoulda Learned

OK, we are a couple of chapters into /Free now, and your feet should be getting pretty wet. You already know enough to do quite a bit of damage, but we are not going to stop here. Before we go on, though, I want to quickly review what we have talked about here.

  • First, you should have a good handle on setting up the IF
  • Second, need I mention that you have to have a semicolon after each statement?
  • Use parentheses as necessary to make the whole thing easier to read and compile (that is, for the compiler to understand what you want).
  • Use the new mathematical comparison operators (versus the old alphabetic abbreviations).
  • If you do use not on an expression, be sure to surround the expression with parenthesis for clarity.
  • In addition, we went over the SELECT/WHEN.
  • And the FOR.
  • Plus the DOW/DOU, which when used in conjunction with a condition statement replace the DOWEQ, operators from positional RPG.
  • And finally, we saw the prototyped call parm, CALLP, and its two
  • But most important, you have not only learned about these things but actually used them in your sample /Free program. You did try each one of these, right? I hope so.

And now we are tired; happy but tired. So let’s rest for just a minute before we move on to /Free I/O.

Want to learn more?  You can pick up Dave Shirey's book, 21st Century RPG: /Free, ILE, and MVC, at the MC Press Bookstore Today!

David Shirey

David Shirey is president of Shirey Consulting Services, providing technical and business consulting services for the IBM i world. Among the services provided are IBM i technical support, including application design and programming services, ERP installation and support, and EDI setup and maintenance. With experience in a wide range of industries (food and beverage to electronics to hard manufacturing to drugs--the legal kind--to medical devices to fulfillment houses) and a wide range of business sizes served (from very large, like Fresh Express, to much smaller, like Labconco), SCS has the knowledge and experience to assist with your technical or business issues. You may contact Dave by email at or by phone at (616) 304-2466.

MC Press books written by David Shirey available now on the MC Press Bookstore.

21st Century RPG: /Free, ILE, and MVC 21st Century RPG: /Free, ILE, and MVC
Boost your productivity, modernize your applications, and upgrade your skills with these powerful coding methods.
List Price $69.95

Now On Sale

More Articles By This Author


Support MC Press Online





  • White Paper: Node.js for Enterprise IBM i Modernization

    SB Profound WP 5539

    If your business is thinking about modernizing your legacy IBM i (also known as AS/400 or iSeries) applications, you will want to read this white paper first!

    Download this paper and learn how Node.js can ensure that you:
    - Modernize on-time and budget - no more lengthy, costly, disruptive app rewrites!
    - Retain your IBM i systems of record
    - Find and hire new development talent
    - Integrate new Node.js applications with your existing RPG, Java, .Net, and PHP apps
    - Extend your IBM i capabilties to include Watson API, Cloud, and Internet of Things

    Read Node.js for Enterprise IBM i Modernization Now!


  • Profound Logic Solution Guide

    SB Profound WP 5539More than ever, there is a demand for IT to deliver innovation.
    Your IBM i has been an essential part of your business operations for years. However, your organization may struggle to maintain the current system and implement new projects.
    The thousands of customers we've worked with and surveyed state that expectations regarding the digital footprint and vision of the companyare not aligned with the current IT environment.

    Get your copy of this important guide today!


  • 2022 IBM i Marketplace Survey Results

    Fortra2022 marks the eighth edition of the IBM i Marketplace Survey Results. Each year, Fortra captures data on how businesses use the IBM i platform and the IT and cybersecurity initiatives it supports.

    Over the years, this survey has become a true industry benchmark, revealing to readers the trends that are shaping and driving the market and providing insight into what the future may bring for this technology.

  • Brunswick bowls a perfect 300 with LANSA!

    FortraBrunswick is the leader in bowling products, services, and industry expertise for the development and renovation of new and existing bowling centers and mixed-use recreation facilities across the entertainment industry. However, the lifeblood of Brunswick’s capital equipment business was running on a 15-year-old software application written in Visual Basic 6 (VB6) with a SQL Server back-end. The application was at the end of its life and needed to be replaced.
    With the help of Visual LANSA, they found an easy-to-use, long-term platform that enabled their team to collaborate, innovate, and integrate with existing systems and databases within a single platform.
    Read the case study to learn how they achieved success and increased the speed of development by 30% with Visual LANSA.


  • Progressive Web Apps: Create a Universal Experience Across All Devices

    LANSAProgressive Web Apps allow you to reach anyone, anywhere, and on any device with a single unified codebase. This means that your applications—regardless of browser, device, or platform—instantly become more reliable and consistent. They are the present and future of application development, and more and more businesses are catching on.
    Download this whitepaper and learn:

    • How PWAs support fast application development and streamline DevOps
    • How to give your business a competitive edge using PWAs
    • What makes progressive web apps so versatile, both online and offline



  • The Power of Coding in a Low-Code Solution

    LANSAWhen it comes to creating your business applications, there are hundreds of coding platforms and programming languages to choose from. These options range from very complex traditional programming languages to Low-Code platforms where sometimes no traditional coding experience is needed.
    Download our whitepaper, The Power of Writing Code in a Low-Code Solution, and:

    • Discover the benefits of Low-code's quick application creation
    • Understand the differences in model-based and language-based Low-Code platforms
    • Explore the strengths of LANSA's Low-Code Solution to Low-Code’s biggest drawbacks



  • Why Migrate When You Can Modernize?

    LANSABusiness users want new applications now. Market and regulatory pressures require faster application updates and delivery into production. Your IBM i developers may be approaching retirement, and you see no sure way to fill their positions with experienced developers. In addition, you may be caught between maintaining your existing applications and the uncertainty of moving to something new.
    In this white paper, you’ll learn how to think of these issues as opportunities rather than problems. We’ll explore motivations to migrate or modernize, their risks and considerations you should be aware of before embarking on a (migration or modernization) project.
    Lastly, we’ll discuss how modernizing IBM i applications with optimized business workflows, integration with other technologies and new mobile and web user interfaces will enable IT – and the business – to experience time-added value and much more.


  • UPDATED: Developer Kit: Making a Business Case for Modernization and Beyond

    Profound Logic Software, Inc.Having trouble getting management approval for modernization projects? The problem may be you're not speaking enough "business" to them.

    This Developer Kit provides you study-backed data and a ready-to-use business case template to help get your very next development project approved!

  • What to Do When Your AS/400 Talent Retires

    FortraIT managers hoping to find new IBM i talent are discovering that the pool of experienced RPG programmers and operators or administrators is small.

    This guide offers strategies and software suggestions to help you plan IT staffing and resources and smooth the transition after your AS/400 talent retires. Read on to learn:

    • Why IBM i skills depletion is a top concern
    • How leading organizations are coping
    • Where automation will make the biggest impact


  • Node.js on IBM i Webinar Series Pt. 2: Setting Up Your Development Tools

    Profound Logic Software, Inc.Have you been wondering about Node.js? Our free Node.js Webinar Series takes you from total beginner to creating a fully-functional IBM i Node.js business application. In Part 2, Brian May teaches you the different tooling options available for writing code, debugging, and using Git for version control. Attend this webinar to learn:

    • Different tools to develop Node.js applications on IBM i
    • Debugging Node.js
    • The basics of Git and tools to help those new to it
    • Using as a pre-built development environment



  • Expert Tips for IBM i Security: Beyond the Basics

    SB PowerTech WC GenericIn this session, IBM i security expert Robin Tatam provides a quick recap of IBM i security basics and guides you through some advanced cybersecurity techniques that can help you take data protection to the next level. Robin will cover:

    • Reducing the risk posed by special authorities
    • Establishing object-level security
    • Overseeing user actions and data access

    Don't miss this chance to take your knowledge of IBM i security beyond the basics.



  • 5 IBM i Security Quick Wins

    SB PowerTech WC GenericIn today’s threat landscape, upper management is laser-focused on cybersecurity. You need to make progress in securing your systems—and make it fast.
    There’s no shortage of actions you could take, but what tactics will actually deliver the results you need? And how can you find a security strategy that fits your budget and time constraints?
    Join top IBM i security expert Robin Tatam as he outlines the five fastest and most impactful changes you can make to strengthen IBM i security this year.
    Your system didn’t become unsecure overnight and you won’t be able to turn it around overnight either. But quick wins are possible with IBM i security, and Robin Tatam will show you how to achieve them.

  • Security Bulletin: Malware Infection Discovered on IBM i Server!

    SB PowerTech WC GenericMalicious programs can bring entire businesses to their knees—and IBM i shops are not immune. It’s critical to grasp the true impact malware can have on IBM i and the network that connects to it. Attend this webinar to gain a thorough understanding of the relationships between:

    • Viruses, native objects, and the integrated file system (IFS)
    • Power Systems and Windows-based viruses and malware
    • PC-based anti-virus scanning versus native IBM i scanning

    There are a number of ways you can minimize your exposure to viruses. IBM i security expert Sandi Moore explains the facts, including how to ensure you're fully protected and compliant with regulations such as PCI.



  • Encryption on IBM i Simplified

    SB PowerTech WC GenericDB2 Field Procedures (FieldProcs) were introduced in IBM i 7.1 and have greatly simplified encryption, often without requiring any application changes. Now you can quickly encrypt sensitive data on the IBM i including PII, PCI, PHI data in your physical files and tables.
    Watch this webinar to learn how you can quickly implement encryption on the IBM i. During the webinar, security expert Robin Tatam will show you how to:

    • Use Field Procedures to automate encryption and decryption
    • Restrict and mask field level access by user or group
    • Meet compliance requirements with effective key management and audit trails


  • Lessons Learned from IBM i Cyber Attacks

    SB PowerTech WC GenericDespite the many options IBM has provided to protect your systems and data, many organizations still struggle to apply appropriate security controls.
    In this webinar, you'll get insight into how the criminals accessed these systems, the fallout from these attacks, and how the incidents could have been avoided by following security best practices.

    • Learn which security gaps cyber criminals love most
    • Find out how other IBM i organizations have fallen victim
    • Get the details on policies and processes you can implement to protect your organization, even when staff works from home

    You will learn the steps you can take to avoid the mistakes made in these examples, as well as other inadequate and misconfigured settings that put businesses at risk.



  • The Power of Coding in a Low-Code Solution

    SB PowerTech WC GenericWhen it comes to creating your business applications, there are hundreds of coding platforms and programming languages to choose from. These options range from very complex traditional programming languages to Low-Code platforms where sometimes no traditional coding experience is needed.
    Download our whitepaper, The Power of Writing Code in a Low-Code Solution, and:

    • Discover the benefits of Low-code's quick application creation
    • Understand the differences in model-based and language-based Low-Code platforms
    • Explore the strengths of LANSA's Low-Code Solution to Low-Code’s biggest drawbacks



  • Node Webinar Series Pt. 1: The World of Node.js on IBM i

    SB Profound WC GenericHave you been wondering about Node.js? Our free Node.js Webinar Series takes you from total beginner to creating a fully-functional IBM i Node.js business application.
    Part 1 will teach you what Node.js is, why it's a great option for IBM i shops, and how to take advantage of the ecosystem surrounding Node.
    In addition to background information, our Director of Product Development Scott Klement will demonstrate applications that take advantage of the Node Package Manager (npm).
    Watch Now.

  • The Biggest Mistakes in IBM i Security

    SB Profound WC Generic The Biggest Mistakes in IBM i Security
    Here’s the harsh reality: cybersecurity pros have to get their jobs right every single day, while an attacker only has to succeed once to do incredible damage.
    Whether that’s thousands of exposed records, millions of dollars in fines and legal fees, or diminished share value, it’s easy to judge organizations that fall victim. IBM i enjoys an enviable reputation for security, but no system is impervious to mistakes.
    Join this webinar to learn about the biggest errors made when securing a Power Systems server.
    This knowledge is critical for ensuring integrity of your application data and preventing you from becoming the next Equifax. It’s also essential for complying with all formal regulations, including SOX, PCI, GDPR, and HIPAA
    Watch Now.

  • Comply in 5! Well, actually UNDER 5 minutes!!

    SB CYBRA PPL 5382

    TRY the one package that solves all your document design and printing challenges on all your platforms.

    Produce bar code labels, electronic forms, ad hoc reports, and RFID tags – without programming! MarkMagic is the only document design and print solution that combines report writing, WYSIWYG label and forms design, and conditional printing in one integrated product.

    Request your trial now!

  • Backup and Recovery on IBM i: Your Strategy for the Unexpected

    FortraRobot automates the routine tasks of iSeries backup and recovery, saving you time and money and making the process safer and more reliable. Automate your backups with the Robot Backup and Recovery Solution. Key features include:
    - Simplified backup procedures
    - Easy data encryption
    - Save media management
    - Guided restoration
    - Seamless product integration
    Make sure your data survives when catastrophe hits. Try the Robot Backup and Recovery Solution FREE for 30 days.

  • Manage IBM i Messages by Exception with Robot

    SB HelpSystems SC 5413Managing messages on your IBM i can be more than a full-time job if you have to do it manually. How can you be sure you won’t miss important system events?
    Automate your message center with the Robot Message Management Solution. Key features include:
    - Automated message management
    - Tailored notifications and automatic escalation
    - System-wide control of your IBM i partitions
    - Two-way system notifications from your mobile device
    - Seamless product integration
    Try the Robot Message Management Solution FREE for 30 days.

  • Easiest Way to Save Money? Stop Printing IBM i Reports

    FortraRobot automates report bursting, distribution, bundling, and archiving, and offers secure, selective online report viewing.
    Manage your reports with the Robot Report Management Solution. Key features include:

    - Automated report distribution
    - View online without delay
    - Browser interface to make notes
    - Custom retention capabilities
    - Seamless product integration
    Rerun another report? Never again. Try the Robot Report Management Solution FREE for 30 days.

  • Hassle-Free IBM i Operations around the Clock

    SB HelpSystems SC 5413For over 30 years, Robot has been a leader in systems management for IBM i.
    Manage your job schedule with the Robot Job Scheduling Solution. Key features include:
    - Automated batch, interactive, and cross-platform scheduling
    - Event-driven dependency processing
    - Centralized monitoring and reporting
    - Audit log and ready-to-use reports
    - Seamless product integration
    Scale your software, not your staff. Try the Robot Job Scheduling Solution FREE for 30 days.