12
Fri, Jul
4 New Articles

RPG Academy: BIF Up Your Code! Use BIFs to Perform Time Operations

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

You've learned how to use BIFs to handle the Date data type and perform a variety of operations with it. It's now time to do the same for the Time data type. I'll show you what RPG has to offer and present a funny function as an example.

 

Now that you mastered Date data type operations thanks to the last two TechTips (1 and 2), let's do the same for the Time data type. As you'll see, there are a lot of similarities between the two: the way the BIFs work is the same, in some cases you can actually use the same BIF, and so on.

 

It's %TIME

The %TIME BIF is similar to %DATE in every way: it converts character, numeric, or timestamp data expressions to type Time. The converted value remains unchanged but is returned as a Time type value.

 

The first parameter is the value to be converted. If you do not specify a value, %TIME() returns the current system time, just like %DATE() returns the system date. The second, optional, parameter is the time format for numeric or character input. Regardless of the input format, the output is returned in *ISO format (HH.MM.SS).

 

But the resemblances don't end here: you can perform Time operations with the plus (+) and minus (–) operators, as long as the operands are of the Time data type or are "Time-type-operation-compatible." And what is that, you ask? Well, just like the %DAYS, %MONTHS, and %YEARS BIFs I explained previously turned numeric data into "Date-type-operation-compatible" format, there are a few BIFs that do the same for Time: %MSECONDS, %SECONDS, %MINUTES, and %HOURS. So if you want to know what the time will be in an hour (or in other words, the current time plus 1 hour), you can code it like this:

 

D W_TIME         S               T   INZ

(…)

C                   EVAL     W_TIME = %TIME() + %HOURS(1)

 

W_Time is defined as a Time data type variable (notice the T on the right side). The %TIME() is used to retrieve the system's current time, and finally + %HOURS(1) is used to add an hour to it. This is just a simple example, but you can do all sorts of things with Time variables: convert, compare, extract parts (using %SUBDT, just like you'd do with a Date variable), and so on.

 

Let's write a funny (or depressing, depends on how much you love your work) function to illustrate some of the possibilities.

 

Do You Know How Long You Have to Work Until the Weekend?

The HowLongUntilWE function calculates how many days and hours you still have to work until a (certainly) much-deserved weekend break. It assumes a couple of things, just to keep the example simple:

  • You work from Monday to Friday;
  • When calculating how long you still have to work today, the break time/lunch time/whatever you call it, is ignored because the function doesn't know at what time it occurs;
  • It ignores the minutes you still have left to work today.

 

Naturally, I could add a few more input parameters and some logic to overcome all of these limitations, but this intends to be a simple example. Having said that, let's code! Here's the first part of the function, from the header to the end of the input parameter validations:

 

*------------------------------------------------------------------------*

*   How long until the weekend (returns the days and hours until the w-e)*

*------------------------------------------------------------------------*

P HowLongUntilWE B                   Export                              

D HowLongUntilWE PI           200A                                      

* Input parameters                                                        

D P_WDStart                     T   VALUE                              

D P_WDEnd                       T   VALUE                              

D P_BreakTime                   2P 0 VALUE                                

                                                                          

* Work variables                                                        

D W_Return       S           200A   INZ(*Blanks)                        

D W_Date         S               D   INZ                                

D W_WDLeft       S             1P 0 INZ                                

D W_WDHours       S             3P 0 INZ                                

D W_WorkTimeLeft S             3P 0 INZ                            

D W_HoursLeftToday...                                                

D                 S             3P 0 INZ                            

D W_TotalLeft     S             3P 0 INZ                              

                                                                      

* Check input parms                                                  

* P_WDStart                                                          

C                   TEST(E)                 P_WDStart                

C                   IF       %Error                                  

C                   EVAL     W_Return = 'Invalid Work Day Start Time!'

C                   RETURN   W_Return                                

C                   ENDIF                                            

* P_WDEnd                                                            

C                   TEST(E)                 P_WDEnd                  

C                   IF       %Error                                  

C                   EVAL     W_Return = 'Invalid Work Day End Time!'

C                   RETURN   W_Return                                

C                   ENDIF                                              

 

Notice how TEST is used to check whether the input parameters contain valid times. I could also check whether the start time is lower than the end time, with a simple comparison: IF P_WDEnd < P_WDStart. The next step is retrieving relevant information for our function. In this case, we'll start by figuring out how many work days are left this week:

 

* If the input parms are ok,                                      

* 1 - Calculate how many work days are left;                      

* (Assuming that you work from Monday to Friday. Day 5 is Friday)  

C                   EVAL     W_WDLeft = 5 - Clc_DayOfWeek(%DATE())

* If this returns a negative number, it means that you still have to

* work the entire week                                            

C                   IF       W_WDLeft < *ZEROS                    

C                   EVAL     W_WDLeft = 5                          

C                   ENDIF                                          

 

Then all I need to do is determine how long a work day is by subtracting the P_WDStart from P_WDEnd using %DIFF and also take into account the break time:

 

* 2.1 - Then calculate how long is a work day, in hours            

C                   EVAL     W_WDHours = %DIFF(P_WDEnd : P_WDStart :

C                                               *HOURS) - P_BreakTime

 

This will be used to calculate the total hours left to work this week:

 

* 2.2 - and multiply by the days;                                

C                   EVAL     W_WorkTimeLeft = W_WDLeft * W_WDHours

 

The math here is simple: assume that today is Wednesday and that you work from 9:00 a.m. to 6:00 p.m., with a one-hour break for lunch. W_WDLeft will be 5 – 3 = 2, because the Clc_DayOfWeek(%DATE()) call will return 3 (the "numeric value" assigned to Wednesday by the Clc_DayOfWeek function). Then the time difference between the start and end times will be 18 – 9 – 1 (P_WDEnd P_WDStart P_BreakTime) = 8, and finally W_WorkTimeLeft will be 8 * 2 = 16. Let's continue and calculate the time left today. This is where things get a little more complicated:

 

* 3 - Finally, calculate and add today's work time left.  

*     There are two options: either your work day hasn't started,    

*     and we'll count the complete work day                          

C                   IF       %TIME() < P_WDStart                    

C                   EVAL     W_WDLeft = W_WDLeft + 1                

C                   ELSE                                              

*     Or it has. The code will calculate how many hours you still have

*     left today, ignoring the break time, because it doesn't know at  

*     what time it would occur                                          

C                   EVAL     W_HoursLeftToday = %DIFF(P_WDEnd : %TIME() :

C                                               *HOURS)                  

C                  ENDIF                                                

C                   EVAL     W_TotalLeft = W_HoursLeftToday            

C                                           + W_WorkTimeLeft            

 

Notice the use of %TIME() to check if you are within your normal work schedule. It's here as a reminder that date and time operations require careful planning and executing to avoid incongruous and unexpected results. The final step is returning the results to the calling program by composing a human-readable string:

 

C                   EVAL     W_Return = 'You have to work '              

C                                         + %Char(W_WDLeft) + ' days and '

C                                         + %Char(W_HoursLeftToday)      

C                                         + ' hours until the weekend!'  

C                                         + ' Or a total of '            

C                                         + %Char(W_TotalLeft) + ' hours!'

* Return the string                                                      

C                   RETURN   W_Return                                    

                                                                          

P HowLongUntilWE E                                                      

 

This string will include the results in two formats: total days plus today's hours left and total hours left. This could be made more complex by including the minutes, but I chose not do to it. However, if you want to try, let me suggest a way to do it: use %DIFF to calculate the difference in minutes instead of hours and then resort to %REM to transform the minutes into hours. For instance, 1 hour and 30 minutes will be returned as 90. The expression %REM(90 : 60) will return 30.

 

Here's How to Find Out!

Let's end this TechTip with a simple example of HowLongUntilWE's usage:

 

*------------------------------------------------------------------------*

*   Variables                                                           *

*------------------------------------------------------------------------*

D W_HowLong     S          200A   INZ(*Blanks)                        

                                                                          

*------------------------------------------------------------------------*

*   Copy Statements                                                      *

*------------------------------------------------------------------------*

* Time Operations                                                        

/Copy QCPYLESRC,TIM_OPS_PR                                              

                                                                          

* Test HowLongUntilWE                                                    

C                   EVAL     W_HowLong = HowLongUntilWE(T'09.00.00' :    

C                                                      T'18.00.00' :    

C                                                       1)              

                                                                          

C                   EVAL     *INLR = *On    

 

Just a quick note regarding the function's parameters: I'm using time literals in this example, again just to keep things simple. In a real-life scenario, you'd use Time data type variables or expressions in their place.

 

That's all for time operations. You can download the source code for the time functions service program and test program here.

 

This TechTip ends the "BIF Up Your Code!" subseries of RPG Academy. I hope that you enjoyed reading it and that, somehow, it helped you solve those "real-life" problems in a more readable and maintainable way. I know I left out quite a few BIFs. Some address more advanced scenarios or very particular situations that are out of the scope of this series. The RPG Academy series will continue with another important aspect of "modern" RPG: code structuring and organization. Until then, let me know what you think about this TechTip and this series in the Comments section below and/or the usual LinkedIn groups.                  

Rafael Victoria-Pereira

Rafael Victória-Pereira has more than 20 years of IBM i experience as a programmer, analyst, and manager. Over that period, he has been an active voice in the IBM i community, encouraging and helping programmers transition to ILE and free-format RPG. Rafael has written more than 100 technical articles about topics ranging from interfaces (the topic for his first book, Flexible Input, Dazzling Output with IBM i) to modern RPG and SQL in his popular RPG Academy and SQL 101 series on mcpressonline.com and in his books Evolve Your RPG Coding and SQL for IBM i: A Database Modernization Guide. Rafael writes in an easy-to-read, practical style that is highly popular with his audience of IBM technology professionals.

Rafael is the Deputy IT Director - Infrastructures and Services at the Luis Simões Group in Portugal. His areas of expertise include programming in the IBM i native languages (RPG, CL, and DB2 SQL) and in "modern" programming languages, such as Java, C#, and Python, as well as project management and consultancy.


MC Press books written by Rafael Victória-Pereira available now on the MC Press Bookstore.

Evolve Your RPG Coding: Move from OPM to ILE...and Beyond Evolve Your RPG Coding: Move from OPM to ILE...and Beyond
Transition to modern RPG programming with this step-by-step guide through ILE and free-format RPG, SQL, and modernization techniques.
List Price $79.95

Now On Sale

Flexible Input, Dazzling Output with IBM i Flexible Input, Dazzling Output with IBM i
Uncover easier, more flexible ways to get data into your system, plus some methods for exporting and presenting the vital business data it contains.
List Price $79.95

Now On Sale

SQL for IBM i: A Database Modernization Guide SQL for IBM i: A Database Modernization Guide
Learn how to use SQL’s capabilities to modernize and enhance your IBM i database.
List Price $79.95

Now On Sale

BLOG COMMENTS POWERED BY DISQUS

LATEST COMMENTS

Support MC Press Online

$0.00 Raised:
$

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: