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Write to Binary File Cluster Size [x-post to ni forums]


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Edit: found this in context help: Arrays and strings in hierarchical data types such as clusters always include size information.

 

http://forums.ni.com/t5/LabVIEW/Write-to-Binary-File-Cluster-Size/td-p/3199224

 

I have a cluster of data I am writing to a file (all different types of numerics, and some U8 arrays). I write the cluster to the binary file with prepend array size set to false. It seems, however, that there is some additional data included (probably so LabVIEW can unflatten back to a cluster). I have proven this by unbundling every element and type casting each one, then getting string lengths for the individual elements and summing them all. The result is the correct number of bytes. But, if I flatten the cluster to string and get that length, it's 48 bytes larger and matches the file size. Am I correct in assuming that LabVIEW is adding some additional metadata for unflattening the binary file back to a cluster, and is there any way to get LabVIEW to not do this?

Edited by GregFreeman
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Edit: found this in context help: Arrays and strings in hierarchical data types such as clusters always include size information.

 

http://forums.ni.com/t5/LabVIEW/Write-to-Binary-File-Cluster-Size/td-p/3199224

 

I have a cluster of data I am writing to a file (all different types of numerics, and some U8 arrays). I write the cluster to the binary file with prepend array size set to false. It seems, however, that there is some additional data included (probably so LabVIEW can unflatten back to a cluster). I have proven this by unbundling every element and type casting each one, then getting string lengths for the individual elements and summing them all. The result is the correct number of bytes. But, if I flatten the cluster to string and get that length, it's 48 bytes larger and matches the file size. Am I correct in assuming that LabVIEW is adding some additional metadata for unflattening the binary file back to a cluster, and is there any way to get LabVIEW to not do this?

 

Yes. If you use the Variant To Flattened String instead you will see the type info on the separate terminal. That won't get rid of the length byte that is prepended to strings though. You will have to process the flattened string and remove that manually.

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