29
Fri, Nov
0 New Articles

Trimming Multiple Characters

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

I've often needed the capability to delete the trailing character within a character field. With RPG IV, IBM provides this capability with the %TRIMx built-in functions, which strip off the trailing and leading blanks from a character field.

  • %TRIML (Trim Left) strips off the blank characters at the beginning a field and returns the content of the field without those leading blanks.
  • %TRIMR (Trim Right) strips off the blank characters at the end of a field and returns the content of the field without those trailing blanks.
  • %TRIM (Trim Both) strips off the blank characters at the beginning and end of a field and returns the content of the field without trailing or leading blanks.

These three built-in functions are a good first try at a function that is sorely needed in manipulating character values. I constantly use %TRIML (Trim Left) to left-justify data within a field. Here's an example:

  compname = %triml(compname)

This statement will strip off the leading blanks from the COMPNAME field and then copy the data to the COMPNAME field. Effectively, this left-justifies the value within the COMPNAME field.

I tend to use this type of statement right after an EXTFMT opcode within RPG IV. Often, the end-user will inadvertently hit the space bar and type the data into a field with an unintentional leading blank. The %TRIML statement thus avoids those types of data integrity issues.

In addition, with the huge boom in CGI RPG IV applications (RPG IV applications with a browser user interface), %TRIML can help eliminate a lot of common problems associated with entering data into a GUI.

As we move deeper into RPG IV, however, I find that what I really need in the %TRIM built-in functions is the ability to specify a character or characters that I want trimmed off my data. For example, suppose I want trailing blanks and trailing periods deleted. What can I do? Would this work?

   compname = %trimr(compname) 

It would not work because only the blanks are eliminated. I cannot specify periods or any other character to be trimmed. This is a problem.

Today, the CHECKR opcode can be used to search a field from the end-point (rightmost character) toward the left. CHECKR searches for the first character in the field that does not match a set of characters. It does not delete characters; it only pinpoints the position in the field where it locates a character that is not like those you've specified. For example:

     C     '. '          CheckR    COMPNAME    nEndPos

In this example, the period and blank characters are used, and the COMPNAME field is searched. CHECKR is supposed to ensure that every character in the COMPNAME field matches the character or characters specified in Factor 1. If it finds a character that does not match, it stops and reports the rogue character's position in the Result field (nEndPos in our example).

So the end position field (nEndPos) contains the location of the first character that is not the same as the character or characters specified in Factor 1.

Knowing that this is what is returned, you now have the ability do something with that information, such as truncate the data in the COMPNAME field. To do this, use the %SUBST built-in function as follows:

     C                   eval      CompName = %subst(CompName:1:nEnd)

If you use both operations immediately following one another, you can mimic a %TRIMR built-in function that supports multiple trim characters, as follows:

     C     '. '          CheckR    COMPNAME    nEndPos
     C                   eval      CompName = %subst(CompName:1:nEnd)

Roll Your Own TRIM Function

Wouldn't it be better to wrap those two tasks into one easy-to-use function? I think so, so I did. Listed in Figure 1 is the source code for the TRIMR procedure. This procedure accepts two parameters: the input string and the trim pattern. Essentially, this procedure has the same syntax as %TRIMR plus an additional, second parameter that allows you to indicate one or more characters that you want trimmed.

P trimR           B                   Export
D trimR           PI          4096A   Varying
D  szInString                 4096A   Value Varying
D  szTrimVal                   256A   Const Varying
D nEnd            S             10I 0

C     szTrimVal     CheckR    szInString    nEnd
 **  If nothing is returned, we return an empty string.
C                   if        NOT %Found()
C                   eval      szInString = ''
C                   else
C                   eval      szInString = %subst(szInString:1:nEnd)
C                   endif
C                   return    szInString
P trimR           E

Figure 1: The TRIMR procedure allows you to indicate characters that you want to trim from the end of a field.

The TRIMR procedure accepts a character field up to 4096 bytes in length. If you need a longer field, simply change the field lengths (wherever you see 4096, change it to the new maximum length that you need).

The first parameter is the original field. Its value will be searched, starting on the right side, for a character that is not specified on the second parameter. The second parameter may be one or more characters. These characters are to be deleted from the original input string.

The procedure works by using the CHECKR opcodes. If a position is returned, it uses the %SUBST built-in function to substring the original input value, and then that new value is returned to the caller.

Please note that the data passed into the procedure is passed by value. This means that a copy of the input parameter is made, and that copy is what is trimmed and substringed. The original field specified on the parameter is not modified--unless, of course, it is the target of the EVAL opcode, as follows:

     C                   eval      CompName = trimR(CompName:' .')

In this example, all blanks and periods are deleted from the right side of the COMPNAME field.

Since it may be useful to also have a similar capability for a %TRIML-like function, I've included the source for the TRIML procedure in Figure 2.

P trimL           B                   Export
D trimL           PI          4096A   Varying
D  szInString                 4096A   VALUE Varying
D  szTrimPattern               256A   Const Varying
D nStart          S             10I 0

C                   if        %Len(szTrimPattern) > 0
C     szTrimPattern CHECK     szInString    nStart
 **  If nothing is returned, we return an empty string.
C                   if        NOT %Found
C                   eval      szInString = ''
C                   else
C                   eval      szInString = %subst(szInString:nStart)
C                   endif
C                   endif
C                   return    szInString
P trimL            E

Figure 2: The TRIML procedure works like the TRIMR procedure, but it trims characters from the beginning of a field.

You'll note that the TRIML procedure uses the CHECK opcode instead of CHECKR. In addition, it uses the return position as the starting value for the %SUBST built-in function. This is because we want to eliminate any leading characters and continue through to the end of the field.

TRIMR and TRIML procedures offer a level of functionality not currently available with %TRIML and %TRIMR. The ability to specify the character or characters that are being trimmed is beneficial and is consistent with most other programming languages. Perhaps someday soon, RPG IV will support this capability natively.

Bob Cozzi has been programming in RPG since 1978. Since then, he has written many articles and several books, including The Modern RPG Language--the most widely used RPG reference manual in the world. Bob is also a very popular speaker at industry events such as RPG World and is the author of his own Web site and of the RPG ToolKit, an add-on library for RPG IV 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: