Tuesday, November 17, 2020

Range test added to RPG

%range bif added to rpg

The latest Technology Refreshes, IBM i 7.4 TR3 and 7.3 TR9, have added something I have wanted for a long time added to the RPG programming language, the ability to test if a value is within a range. This has been achieved by the introduction of a new Built in Function, %RANGE, and a new operation code, IN.

The syntax is very similar to the Range test I use in SQL:

if <value or variable> in %range(<minimum value or variable> :
                                 <maximum value or variable>) ;

Let me get on with some simple examples. First with a date:

01  **free

02  dcl-s InRange ind ;

06  if %date() in %range(d'2020-11-01' : d'2020-11-30') ;
07    InRange = *on ;
08  endif ;

09  dsply ('Date = ' + %char(InRange)) ;

Line 1: If I am doing things in RPG why would I want to do it in an old version of our favorite programming language?

Line 2: The only purpose for this variable is to know if the Range test was successful or not.

Lines 3 – 5: Will be shown later.

Line 6: Testing the current date, using built in function %DATE() with no parameter, if it is in this month, November 1 – 30, and this year.

Line 7: If the test was successful, today is in this month, then the indicator InRange is turned on.

Line 9: I am using the Display operation code, DSPLY, to see the value of the indicator and whether my test was successful. Which it was:

DSPLY  Date = 1

Now with numbers...

10  if 7 in %range(1 : 10) ;
11    InRange = *on ;
12  else ;
13    InRange = *off ;
14  endif ;

15  dsply ('Number = ' + %char(InRange)) ;

Line 10: Is the number seven in the range of numbers between one and ten?

Line 11: Of course it is.

Line 15: So my indicator will display:

DSPLY  Number = 1

Next character values...

16  if 'ABCD' in %range('A' : 'B') ;
17    InRange = *on ;
18  else ;
19    InRange = *off ;
20  endif ;

21  dsply ('Char 1 = ' + %char(InRange)) ;

Line 16: "ABCD" is between the values of "A" and "B".

Line 21: Therefore, the indicator is on.

DSPLY  Char 1 = 1

What happens if I reverse the values in the Range BiF, and put the higher value in the first parameter and the lower in the second.

22  if 'ABCD' in %range('B' : 'A') ;
23    InRange = *on ;
24  else ;
25    InRange = *off ;
26 endif ;

27  dsply ('Char 2 = ' + %char(InRange)) ;

Line 22: No value can satisfy this range criteria.

Line 27: And the indicator is off.

DSPLY  Char 2 = 0

I have used values above, not variables. Here are a couple examples using variables:

03  dcl-s MinValue char(10) inz('Houston') ;
04  dcl-s MaxValue like(MinValue) inz('Yznaga') ;
05  dcl-s TestValue like(MinValue) inz('Dallas') ;


28  if TestValue in %range(MinValue : MaxValue) ;
29    InRange = *on ;
30  else ;
31    InRange = *off ;
32  endif ;

33  dsply ('City 1 = ' + %char(InRange)) ;

Lines 3 – 5: Here are those missing lines I mentioned before, that define the three variables I will be using.

Line 28: Testing if the city Dallas is within the range of city names of Houston to Yznaga.

Line 33: And it is not so the indicator is off.

DSPLY  City 1 = 0

Let me try that again with another city name.

34  TestValue = 'Round Rock' ;

35  if TestValue in %range(MinValue : MaxValue) ;
36    InRange = *on ;
37  else ;
38    InRange = *off ;
39  endif ;

40  dsply ('City 2 = ' + %char(InRange)) ;

Line 35: The city of Round Rock is in the range.

Line 40: And the indicator shows that.

DSPLY  City 2 = 1

These two are a great addition and I can see me using them a lot. Now what about a %VALUES BiF?

 

You can learn more about the %RANGE Built in Function from the IBM website here.

 

This article was written for IBM i 7.4 TR3 and 7.3 TR9.

16 comments:

  1. Happy to hear about this. Thanks. Also, can tell you're a Texan now!

    ReplyDelete
  2. if 'ABCD' in %range('A' : 'B') ;

    How is this true? Is only the first byte being tested, because the range values are 1 byte?

    ReplyDelete
    Replies
    1. All code I show is tested before I include it in a post. I have to admit I could not find a reference in the documentation stating if it only checks the first byte or whether is checks the entire string.

      Delete
    2. Documentation says those statements are equivalent
      IF x IN %RANGE(y1 : y2);
      IF x >= y1 AND x <= y2;

      I think
      if 'ABCD' in %range('A' : 'B') ; is equivalent to
      if 'ABCD' >= 'A' and 'ABCD' <= 'B'
      and what you have in mind is
      if %subst('ABCD':1:1) in %range('A' : 'B') ;

      Delete
  3. If you compare 'ABCD' with 'A', 'ABCD' is greater then 'A' but if you compare 'ABCD' with 'B, 'ABCD' is lower then 'A' so the result of %range is correct.

    Is like you made

    IF 'ABCD' IN %RANGE('A ' : 'B ');

    ReplyDelete
  4. Try this

    IF 'ABCD' IN %RANGE('A' : 'A'); This is false so you can understand that is not the first byte tested

    ReplyDelete
  5. can you use it to set an indicator field directly:

    TestFldValidInd = testFld in %range(minFld : maxFld);

    ReplyDelete
  6. I am thinking for screen validation routine, flagging all of the errors and redisplaying

    ReplyDelete
  7. Do you prefer the "if" wrapper or write the check in one line like:

    InRange = ( TestValue in %range(MinValue : MaxValue)) ;

    ReplyDelete
    Replies
    1. if the only logic I am going to do is set an indicator based on the results of the if, I prefer to set it directly with comments as to what it is doing.

      Delete
  8. Simon, what do you mean by a %VALUES bif?

    ReplyDelete
    Replies
    1. It is a long held wish of mine where I could have a BiF that I could then compare a variable to a list of values.
      But as you know that is now possible and will be revealed tomorrow.

      Delete
    2. You already have it Simon - it os called %LIST and is in the same set of PTFs.

      Delete
    3. I was using this as a "teaser" for today's post, which gives plenty examples of using %LIST.

      Delete
  9. If Answer in %Values(‘Y’: ‘N’); would be nice, where the values can be any number of parameters.

    ReplyDelete

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