Case Selector range Notation

[Taylorh140]

I noticed something inconsistent today with case selector, specifically the inclusion of the sequence terminators.

Guess the outputs for Q1-4.

The purpose of this post is mostly to help others not make this (seemly easy) mistake. Also to ask how is this discrepancy useful? 

[ensegre]

you mean "String ranges: A range of a..c includes all strings beginning with a or b, but not c." which is known and stated? I read time ago a discussion about its rationale, but I don't remember where.

[Taylorh140]

Absolutely, I find it weird. It doesn't match the Integer notation and even more so it includes the first item but not the last. I was using to match numeric 0-9 which yes you could use a regex but its a range 0-9 simple case statement should work. its weird to put "0"..":" I had to reference my ASCII table just to know which one to use. And I do agree it is stated in the reference above, but I generally dislike inconsistency especially with logical concepts that should be transferable; just because something is known doesn't mean it cannot be incorrectly inferred or forgotten. That being said, I would really like to know the rationale, however if there has to be a discussion it doesn't bode well for the "feature".

[drjdpowell]

With integers you can do ranges like <=3 and >=4, and there is no gaps.  But with non-integers you cant: <=3 and >=4 misses out all numbers between 3 and 4.  But you also can't do <=4 and >=4, since then 4 falls in both ranges.  So you have to do <4 and >=4, and thus have a range (<4) which does not include its endpoint, confusingly.

Strings are actually more like floats, than like integers; between "c" and "d" is "ca", "cz", "czzzzzzzzzzzzzzzzzz", etc.  Even if "a..c" included "c", it would not include "ca".  There is no way to do non-overlapping-but-complete ranges with strings without not including one endpoint.  Unfortunately, people intuitively think of "a..c" as anything starting with "a" to "c", but it isn't.

[Darren]

rolf's explanation is the best discussion of the string range rationale I've seen:

https://forums.ni.com/t5/LabVIEW/Darren-s-Weekly-Nugget-03-09-2009/m-p/867644#M392955

 

[ShaunR]

I've been doing C++ recently after a very long time. I'd almost forgotten how much pain is circumvented with LabVIEW case structures.

With no multi-line literals (can't just paste a key into a page). No "switch" [case statement] with strings.....period. Case sensitive whether you like it or not. Thank god it's almost over and then I can control it with LabVIEW.

[Taylorh140]

I see what your saying now. When looking at a single ASCII character it would make sense to include the last point just like they do with integers. however there is not a character type only a character array type (string), and in an effort to make the case statement ranges more useful in the string realm they made a notation that is essentially a begins with function. (regex would probably be more useful/but slightly slower). This does explain it a bit though.

@ShaunR I am also glad it is not C++.