20
Sat, Jul
2 New Articles

MoveA: One Last Time

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

MoveA? Again? Still? Really?

 

Author's note: The subject of the RPG opcode MoveA (as it pertains to free-format RPG) keeps coming up in articles, blogs, and forums throughout our industry. It's time to put it to rest. The following excerpt from the book Free-Format RPG IV should supply all you need to handle the free-format conversion of this opcode.

Solution for the Fixed-Format MoveA Operation

One of the operations that free-format RPG IV doesn't support is MoveA (Move array). You can perform the equivalent function, however, by using various built-in functions.

History

IBM created the MoveA operation for RPG II programmers, to solve a then-current need for character manipulation. At the time, no Scan (Scan string), Subst (Substring), or Cat (Concatenate two strings) operation existed, and built-in functions were still decades away. MoveA's purpose was to move a character field to an array defined as character with length 1 and a number of elements equal to the length of the field. Inside the array, programmers could scan and change the field using array indexes.

 

By converting the field to an array, you could perform character searches (scanning) using the array lookup function. The Lookup operation code returns the location found in the array in an index, allowing modification of the array element.

 

You can use the MoveA operation to load a field starting anywhere in the array, not just in position 1, to imitate a substring function. You can place multiple fields in the array, emulating the concatenation function. Character management is easy if the character locations are available using an index; in this case, the character locations are available in array elements. After performing all character management operations, you can convert the array back to a field, again using the MoveA operation.

 

Another function of MoveA is moving array data to another array. In the implementation of this function, there is no recognition of array boundaries. The sending array can start at any array index, and the receiving array can start at any array index.

The Free-Format Solution

In RPG IV, if you must move a field to an array rather than manage the field using character-string built-in functions, consider the following:

                                           

     D Array        S          1      Dim(30)

     D Field        S         30

     D i            S          2  0 

      /free

       For i = 1 to %len(Field);

         Array(i) = %subst(Field:i:1);

       Endfor;

 

To move the array back to the field:

 

       For i = 1 to %len(Field);

         %subst(Field:i:1) = Array(i);

       Endfor;

 

In most cases, however, you won't need these two routines because RPG IV provides many good character-management built-in functions.

 

The free-format emulation of MoveA begins with the %scan built-in function. Finding a single character or small string within a character string is easy using %scan. As an example, if you are locating the small string "qu" in another string, say 'Albuquerque', just specify:

 

   Location = %scan('qu':'Albuquerque');

 

After this line of code is executed, Location has the value 5. To find the second 'qu', you need some loop logic.

 

To replace one or more characters in a character string, you can use the %subst or %replace built-in function. Here's an example: Say you want to replace all occurrences of "i" in the character string "Mississippi" with "a". You can use the following routine to do so:

 

     D Search_char     S        1        Inz('i')

     D Char_string     S       30        Inz('Mississippi')

     D i               S        2  0        

      /free

       i = 1;

       Dou i = *Zero;

         i = %scan(Search_char:Char_string:i);

         If i > * Zero;

           %subst(Char_string:i:1) = 'a';

           i += 1;

         Endif;

       Enddo;

 

Another way to do the same function is to use the built-in function %xlate.

 

     D Search          S        1        Inz('i')

     D New             S        1        Inz('a')

     D Char_string     S       30        Inz('Mississippi')

      /free

       Char_String = %xlate(Search:New:Char_String);

 

To build a long character string from smaller strings, consider the following example of concatenation:

 

D  F1      S         10     inz ('Now')

D  F2      S         10     inz ('is')

D  F3      S         10     inz ('the')

D  F4      S         10     inz ('time')

D  String  S         50

 

      /free

       String = %trim(F1) + ' '

                + %trim(F2) + ' '

                + %trim(F3) + ' '

                + %trim(F4) + '.';

 

The %Subarr Built-in Function

Moving the data of an array to an array is a bit trickier than some of the operations examined above. V5R3 provides a new built-in function, %subarr, that helps get the job done.

 

Let's look at an example where an element of an array is defined as 100 bytes, and another array is defined as length 1 with 100 elements. We want to move all elements of the 100 element array (Array1) to the element of Array2, whose index is i. The fixed-format scenario would be as follows:

 

     D Array1           s              1    Dim(100)

     D Array2           s            100    Dim(50)

     D i                s              5U 0

     D j                s              5U 0

     D Arx              s                   Dim(100)

     D                                      Like(Array1)

     D                                      Based(Ptr)            

 

     C                   Movea  Array1       Array2(i)

 

To perform the same operation in free-format, you have two alternatives:

 

      /free

       For j = 1 to %elem(Array1); // Loop  1 to 100

         %subst(Array2(i):j:1) = Array1(j); // Move 1 char

       Endfor;

       

       // Another solution using %subarr and a based array

       // template

       

       Ptr = %addr(Array2(i));  // Ptr to Array2 element i 

       Arx = %subarr(Array1:1); // Move array to array

 

JIM MARTIN

Jim Martin holds a BS degree in mathematics and an MS in computer science. For 26 years, he was employed by IBM, where he wrote RPG applications for customers and worked in the programming laboratory as a programmer on portions of CPF and the OS/400 operating system. After leaving IBM, Jim took post-graduate work in computer science and performed RPG training. He is an IBM-certified RPG IV developer and author of multiple bestselling editions of Free-Format RPG IV, which, since the book's initial publication in 2005, have taught thousands of RPG IV programmers how to be successful with the free-format coding style.


MC Press books written by Jim Martin available now on the MC Press Bookstore.

Free-Format RPG IV: Third Edition Free-Format RPG IV: Third Edition
Improve productivity, readability, and program maintenance with the free-format style of programming in RPG IV.
List Price $59.95

Now On Sale

Free-Format RPG IV: Second Edition Free-Format RPG IV: Second Edition
>Make the transition from coding in fixed-format RPG to free format.
List Price $59.95

Now On Sale

Functions in Free-Format RPG IV Functions in Free-Format RPG IV
Here’s the ultimate guide to writing RPG IV programs with functions in the free-format style.
List Price $59.95

Now On Sale

BLOG COMMENTS POWERED BY DISQUS

LATEST COMMENTS

Support MC Press Online

$

Book Reviews

Resource Center

  • SB Profound WC 5536 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. You can find Part 1 here. In Part 2 of our free Node.js Webinar Series, Brian May teaches you the different tooling options available for writing code, debugging, and using Git for version control. Brian will briefly discuss the different tools available, and demonstrate his preferred setup for Node development on IBM i or any platform. Attend this webinar to learn:

  • 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 company are not aligned with the current IT environment.

  • SB HelpSystems ROBOT Generic IBM announced the E1080 servers using the latest Power10 processor in September 2021. The most powerful processor from IBM to date, Power10 is designed to handle the demands of doing business in today’s high-tech atmosphere, including running cloud applications, supporting big data, and managing AI workloads. But what does Power10 mean for your data center? In this recorded webinar, IBMers Dan Sundt and Dylan Boday join IBM Power Champion Tom Huntington for a discussion on why Power10 technology is the right strategic investment if you run IBM i, AIX, or Linux. In this action-packed hour, Tom will share trends from the IBM i and AIX user communities while Dan and Dylan dive into the tech specs for key hardware, including:

  • Magic MarkTRY 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. Make sure your data survives when catastrophe hits. Request your trial now!  Request Now.

  • SB HelpSystems ROBOT GenericForms of ransomware has been around for over 30 years, and with more and more organizations suffering attacks each year, it continues to endure. What has made ransomware such a durable threat and what is the best way to combat it? In order to prevent ransomware, organizations must first understand how it works.

  • SB HelpSystems ROBOT GenericIT security is a top priority for businesses around the world, but most IBM i pros don’t know where to begin—and most cybersecurity experts don’t know IBM i. In this session, Robin Tatam explores the business impact of lax IBM i security, the top vulnerabilities putting IBM i at risk, and the steps you can take to protect your organization. If you’re looking to avoid unexpected downtime or corrupted data, you don’t want to miss this session.

  • SB HelpSystems ROBOT GenericCan you trust all of your users all of the time? A typical end user receives 16 malicious emails each month, but only 17 percent of these phishing campaigns are reported to IT. Once an attack is underway, most organizations won’t discover the breach until six months later. A staggering amount of damage can occur in that time. Despite these risks, 93 percent of organizations are leaving their IBM i systems vulnerable to cybercrime. In this on-demand webinar, IBM i security experts Robin Tatam and Sandi Moore will reveal:

  • FORTRA Disaster protection is vital to every business. Yet, it often consists of patched together procedures that are prone to error. From automatic backups to data encryption to media management, Robot automates the routine (yet often complex) 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:

  • FORTRAManaging messages on your IBM i can be more than a full-time job if you have to do it manually. Messages need a response and resources must be monitored—often over multiple systems and across platforms. 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:

  • FORTRAThe thought of printing, distributing, and storing iSeries reports manually may reduce you to tears. Paper and labor costs associated with report generation can spiral out of control. Mountains of paper threaten to swamp your files. Robot 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:

  • FORTRAFor over 30 years, Robot has been a leader in systems management for IBM i. With batch job creation and scheduling at its core, the Robot Job Scheduling Solution reduces the opportunity for human error and helps you maintain service levels, automating even the biggest, most complex runbooks. Manage your job schedule with the Robot Job Scheduling Solution. Key features include:

  • LANSA Business 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.

  • 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:

  • LANSASupply Chain is becoming increasingly complex and unpredictable. From raw materials for manufacturing to food supply chains, the journey from source to production to delivery to consumers is marred with inefficiencies, manual processes, shortages, recalls, counterfeits, and scandals. In this webinar, we discuss how:

  • The MC Resource Centers bring you the widest selection of white papers, trial software, and on-demand webcasts for you to choose from. >> Review the list of White Papers, Trial Software or On-Demand Webcast at the MC Press Resource Center. >> Add the items to yru Cart and complet he checkout process and submit

  • Profound Logic 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.

  • SB Profound WC 5536Join us for this hour-long webcast that will explore:

  • Fortra IT managers hoping to find new IBM i talent are discovering that the pool of experienced RPG programmers and operators or administrators with intimate knowledge of the operating system and the applications that run on it is small. This begs the question: How will you manage the platform that supports such a big part of your business? 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: