Bug in conditional for loop with an empty array

[TrevMrgn]

Here is a VI that demonstrates the error - some cases work, some don't. Just run the VI.

All 'Size' arrays should be the same.

Notice that strings behave differently than numbers or booleans - probably due to different memory allocation.

Trevor

[Thoric]

Aha! Now I see it! Yes, running your vi in 8.5.1 demonstrates this bug. In 8.6 it does not occur.

 

Message Edited by Thoric on 05-06-2009 08:54 AM

[Thoric]

Oh, now this is odd. If I open a blank vi, and drag and drop your entire vi block diagram into it, then run it, I get no bug:

It might be worth you running my vi (attached) to see if you get this error. If not, then something is awry with your LabVIEW! 

Message Edited by Thoric on 05-06-2009 08:59 AM

[TrevMrgn]

If I run your VI I get no error unless I make a trivial change that (I presume) requires recompilation.

i.e. moving things or adding labels has no effect; adding a boolean constant outside the main loop does.

Thoric: Does editing my VI make the error go away?

 I will try a clean reinstallation of LabVIEW.

Trevor

[Thoric]

Trevor,

If I recompile your vi (Hold CTRL and click Run), the error goes away. The problem seems to be with the compilation. I'm running 8.5.1 by the way, are you using 8.5.0?

[TrevMrgn]

I am running 8.5.0.

Could someone with this version try the example please?  So I can determine whether it is my system or a bug in 8.5.0

I have tried both a 'Repair' and uninstall and reinstall without any change.

Thanks, Trevor

[Thoric · Accepted solution]

Trevor,

I justed searched the 8.5.1 bug fixes list (link) and it identifies this behaviour in ID# 4C5BIJV6.

Looks like you need to upgrade, or perhaps the workaround they describe in that document will work for you?

Message Edited by Thoric on 05-07-2009 11:52 AM

[TrevMrgn]

Thanks, Thoric

There is no workaround described in the 8.5.1 bug fixes, and that is the only place I can find where it is referenced.

I can think of two workarounds:

1: Use an if-empty conditional

2: Prefix/append the array with a dummy element so it is never empty.

Is there a link path to this document from the ni.com website? (except the link you just posted in this forum). If so where?

[Thoric]

The workaround is at the bottom of here, which is accessible by selecting the ID# from within the link I provided before. However, on closer inspection, It simply requests the user to recompile their code, which I seem to remember you saying did not work for you now that I think about it.

The patch upgrade from 8.5.0 to 8.5.1 ought to be freely downloadable from NI.com if you haven't got it? Try www.ni.com/downloads, then drivers and updates, then searching for LabVIEW 8.5.1