29
Fri, Nov
0 New Articles

Tips and Techniques: Converting Date to Decimal to Date

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

In my experience, most people have standardized on eight-digit zoned numeric fields in their database files for date fields. The format is typically YYYYMMDD.

This standard obviously came from the Y2K era and supports RPG III as well as RPG IV. RPG III does not recognize date data type values in database files, so using true date data types would not have been a viable alternative. RPG III only allows you to convert date fields to character, which is pretty useless.

But in RPG IV, we can take advantage of the date arithmetic operation codes, such as ADDDUR, SUBDUR, and EXTRCT. But these opcodes only work with true date data type fields. Therefore, we have to convert any eight-digit field that contains date information into a true date data type variable.

RPG IV supports this type of conversion via the MOVE opcode. For example, if our database file contains an eight-digit zoned numeric field named ORDDTE, we can convert that field's value into a real date field using the following RPG IV syntax:







D OrderDate       S               D   DatFmt(*ISO)
D DueDate         S               D   DatFmt(*ISO)

C     *ISO          MOVE      ORDDTE        ORDERDATE
C                   ADDDUR    30:*DAYS      DUEDATE
C     *ISO          MOVE      DUEDATE       DUEDTE

In this example, the ORDDTE field is moved into the ORDERDATE field. The MOVE opcode does the conversion for us. The value in Factor 1 identifies the format of the ORDDTE field. Then, 30 days are added to the ORDERDATE, calculating the DUEDATE. Then, DUEDATE is converted into an eight-digit zoned numeric value in YYYYMMDD format. The *ISO in Factor 1 of the second MOVE opcode controls the target date format of the numeric field.

The MOVE opcode is a powerful tool. The EVAL opcode, which supplants the MOVE in free-format, does not offer nearly the capabilities of MOVE. For example, you cannot copy a date field to a numeric or character target variable using EVAL.

This restriction causes programmers to use certain built-in functions to perform the conversion. For example, to convert a date field to character format, %CHAR would be used as follows:

D DueDate         S               D   DatFmt(*ISO)
D szDUE           S             10A   
C                   eval      szDue = %char(DueDate:*USA)

 

This example converts the date field DUEDATE into MM/DD/YYYY format and copies it to the szDUE field. Again, a date field in a character field is rarely needed (except for output purposes).
 

To convert a date field into a numeric field, other built-in functions are needed--particularly, %INT.


D DueDate         S               D   DatFmt(*ISO)
D DUEDTE          S              8S 0  
C                   eval      DueDte = %int(%char(DueDate:*ISO0))

In this example, the %INT built-in function converts the character value to numeric. In order for the date to appear as a character string without the embedded date edit symbols, the %CHAR built-in function is used with the optional second parameter specified as %ISO0. This date formatting code has a trailing zero, which indicates that date separators will not be inserted into the result. So, for example, instead of a value of 2004-09-30, the result is 20040930.

If you are on i5/OS V5R3, you can use the %DEC built-in function to accomplish the same thing:

D DueDate         S               D   DatFmt(*ISO)
D DUEDTE          S              8S 0  
C                   eval      DueDte = %dec(DueDate:*ISO)

To convert the value back to a date field, use the %DATE built-in function:

D DueDate         S               D   DatFmt(*ISO)
D DUEDTE          S              8S 0  
C                   eval      DueDate = %date(DueDte:*ISO)

 

If you have the RPG xTools, you can use the DateToDec() and DecToDate() procedures to accomplish the same task. The benefits of the xTools in this situation is that they work on OS/400 V4R5 and later, whereas some other techniques work only on V5R1 and some work only on V5R2, while the %DEC example doesn't work until V5R3. We get to try to keep it straight.
 

If you have the xTools, here is what you would need to do:


 /INCLUDE XTOOLS,QCPYSRC,DATES
D DueDate         S               D   DatFmt(*ISO)
D DUEDTE          S              8S 0  
 **  Convert Date to Decimal
C                   eval      DueDte = DateToDec(DueDate:*ISO)
 **  Convert Decimal to Date
C                   eval      DueDate = DecToDate(DueDate:*ISO)

The syntax is marginally cleaner, and as I said, it works on V4R5 and later, whereas the %int(%char()) technique requires V5R2 or later.

Also note that the date format code does not need the trailing zero because you're converting to decimal, and the procedure is smart enough to know you don't need the separators.

Use any of these techniques to convert between date fields and decimal fields: Read from your database, convert to date, do the date math, and then convert the results back to numeric fields and write them to your database files. It ain't rocket science.

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: