February 2007

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« Array vs ArrayList | Main | Power Collections »


Joe G.

So is there a nifty way to do this in reverse? E.g., can I take a LabVIEW array and stuff it into an ArrayList with a similar technique?

Brian Tyler

Yes and no. Using the other VI in that vi.lib library, To Object.vi, you can convert a LV array to a .NET array explicitly. What comes out of that VI, however, is System.Object.

To be able to pass it into the constructor of an ArrayList, you must first cast it to the ICollection interface. This is where the bug in LV 7 bites you - LV 7 doesn't support casting to interfaces in most cases. So you need to either create a helper assembly to do the cast for you or upgrade to Constellation when it ships.

So basically the answer is a qualified yes!

Mark Smith

Is there a general solution to get the elements of a collection? Specifically, I want to use some classes in the System.XML namespace to get and replace some document elements. The method returns a nodeList. So, is this practical to do straight from LabVIEW or should I wrap the functionality in a DLL that returns an array to LabVIEW?


Brian Tyler

I'm assuming you're talking about an XmlNodeList. The problem here is that it only supports the IEnumerable interface. This means converting it to an array in LabVIEW can be expensive if you have a large number of elements. You can always converts an enumerable into a LV array, one element at a time, but you can see the cost as it grows in size.

My recommendation to you and everyone else is

1. If you can write the .NET code, and it's easy to encapsulate into a handy routine that can be reused, then do that and return an array.

2. If you can't, or there would be dozens of these little .NET routines, consider not converting to a LV array. Perhaps you should provide accessor VIs, or create a LabVIEW class (8.20 and on feature).


Hey. New around here and figured that I should post and say hi.

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