02
Sat, Nov
2 New Articles

Sorting and Searching Arrays Becomes More Manageable in V5R3

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

One of the enhancements IBM introduced in i5/OS V5R3 is the %SUBARR built-in function. This built-in function is helpful to the growing number of programmers who use dynamic array techniques. In addition, %SUBARR is very useful when a traditional array is used and only a portion of the array's elements is needed.

The %SUBARR built-in function allows you to subscript an array by specifying both the starting array element and the number of elements you want to manipulate. You then pass this value to a SORTA, %LOOKUP, %XFOOT, or just about any other operation code or built-in function. The scope of the array elements is limited to what you have specified, rather than the entire array. This is good news for all of us.
For example, if you have an array that contains the sales figures for any period of time up to 10 years, you might have an array with several thousand elements. But what happens when you need to store and sort only a year's worth of data? Some people initialize the arrays to all 0s or all 9s, depending on the sort criteria. With %SUBARR, you simply determine how many array elements you want to sort and then issue the SORTA opcode.

The syntax for %SUBARR is shown below. The first parameter is the name of the array. The second parameter is the starting element. Normally, this is set to 1, but it may be any element in the array. The third and final parameter is the number of elements you want to subscript. This is an optional parameter that, if not specified, defaults to the end of the array.

%SUBARR(array-name : starting-element {: number-of-elements} )

Here's an example:

D DailySales      S              7P 2 Dim(3660)

 //  Populate a year's worth of elements.

 //  Sort the array: Sort a year's worth of data only.
C                   sorta     %subarr(DailySales:1:366)

Notice that the starting array element and the number of elements are specified as the second and third parameters of %SUBARR, respectively.

As I mentioned, in addition to traditional arrays, %SUBARR may be used with dynamic arrays. With the rise in new CGI programs and efficient storage utilization, using an array with a dynamic number of elements is becoming standard practice for RPG IV programmers. One of the shortcomings of dynamic arrays used to be that you could not subscript the array--that is, scope the manipulation of the array elements to those that you have allocated memory for. But now you can.

The same technique used for traditional fixed-element arrays can be used for dynamic arrays. In fact, it was designed in part because of the increase in dynamic array techniques being used by RPG IV developers.

Using %SUBARR with a dynamic array isn't all that different from using it with fixed-element arrays. In fact, it is virtually identical. The code below shows the DailySales array set up as a dynamic array.

D pArr            S               *   Inz
D DailySales      S              7P 2 Dim(3660) BASED(pArr)

 //  First, allocate the memory for 1 year of sales.
C                   eval      pArr = %Alloc(%Size(DailySales)*366)
 //  Populate the 366 elements using traditional techniques.
C**.. TODO: Insert code here to populate the array.

 //  Now sort the array, but only sort a year's worth of data
C                   sorta     %subarr(DailySales:1:366)

In this example, I use the %ALLOC built-in function to allocate the necessary storage for a year's worth of sales data. Then, the program fills in the array with the sales figures and calls the SORTA opcode to order the sales figures in ascending sequence.

The %SUBARR built-in function may be used in an expression on the EVAL and EVALR opcodes, and it will only impact the elements within the scope of the %SUBARR or extract those elements. In addition, the SORTA and RETURN support %SUBARR in the Extended Factor 2.

The %XFOOT built-in function supports a %SUBARR array as its parameter. But %LOOKUPxx does not because %LOOKUPxx already has the capabilities (starting element and element count) as %SUBARR.

One interesting byproduct of %SUBARR is the ability to add the elements of one array to the elements of another array. The %SUBARR built-in function gives you the ability to add elements 4, 5, and 6 to elements 1, 2, and 3. For example:

D ArrA            S              7P 2 Dim(52)
D ArrB            S              7P 2 Dim(104)

 ** Add ArrA(4,5,6) to ArrB(1,2,3)
C                   eval      ArrB += %subarr(ArrA:4:3)

 ** Add ArrA(4,5,6) to ArrB(56,57,58)
C                   eval      %subarr(ArrB:56:3) += %subarr(ArrA:4:3)

In this example, the short-form math operators are used to add the three elements from ARRA to ARRB.

Let your imagination run with this new capability. You'll probably have plenty of time for that, because unfortunately most of us won't be onV5R3 until at least next year.

Bob Cozzi is a programmer/consultant, writer/author, and software developer. His popular RPG xTools add-on subprocedure library for RPG IV is fast becoming a standard with RPG developers. His book The Modern RPG Language has been the most widely used RPG programming book for more than a decade. He, along with others, speaks at and produces the highly popular RPG World conference for RPG programmers.

BOB COZZI

Bob Cozzi is a programmer/consultant, writer/author, and software developer. His popular RPG xTools add-on subprocedure library for RPG IV is fast becoming a standard with RPG developers. His book The Modern RPG Language has been the most widely used RPG programming book for more than a decade. He, along with others, speaks at and produces the highly popular RPG World conference for RPG programmers.


MC Press books written by Robert Cozzi available now on the MC Press Bookstore.

RPG TnT RPG TnT
Get this jam-packed resource of quick, easy-to-implement RPG tips!
List Price $65.00

Now On Sale

The Modern RPG IV Language The Modern RPG IV Language
Cozzi on everything RPG! What more could you want?
List Price $99.95

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: