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Variant To Data

LabVIEW 8.5 Help
August 2007

NI Part Number:
371361D-01

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Converts variant data to a LabVIEW data type so LabVIEW can display or process the data. You also can use this function to convert variant data to ActiveX data.

Details  

type is the LabVIEW data type to which you want to convert the variant data. type can be any data type. However, this function returns an error if LabVIEW cannot convert the data wired to variant to the data type you wire to this input. If the data is integers, you can coerce the data to another numeric representation, such as an extended-precision, floating-point number.
variant is the variant data you want to convert to the LabVIEW data type specified in type.
error in describes error conditions that occur before this VI or function runs. The default is no error. If an error occurred before this VI or function runs, the VI or function passes the error in value to error out. This VI or function runs normally only if no error occurred before this VI or function runs. If an error occurs while this VI or function runs, it runs normally and sets its own error status in error out. Use the Simple Error Handler or General Error Handler VIs to display the description of the error code. Use error in and error out to check errors and to specify execution order by wiring error out from one node to error in of the next node.
status is TRUE (X) if an error occurred before this VI or function ran or FALSE (checkmark) to indicate a warning or that no error occurred before this VI or function ran. The default is FALSE.
code is the error or warning code. The default is 0. If status is TRUE, code is a nonzero error code. If status is FALSE, code is 0 or a warning code.
source specifies the origin of the error or warning and is, in most cases, the name of the VI or function that produced the error or warning. The default is an empty string.
data is the variant changed to the data type specified by type. If variant could not be converted to the data type specified, this data returns the default value for the data type.
error out contains error information. If error in indicates that an error occurred before this VI or function ran, error out contains the same error information. Otherwise, it describes the error status that this VI or function produces. Right-click the error out front panel indicator and select Explain Error from the shortcut menu for more information about the error.
status is TRUE (X) if an error occurred or FALSE (checkmark) to indicate a warning or that no error occurred.
code is the error or warning code. If status is TRUE, code is a nonzero error code. If status is FALSE, code is 0 or a warning code.
source describes the origin of the error or warning and is, in most cases, the name of the VI or function that produced the error or warning.

Variant To Data Details

This function also serves as the QueryInterface method of ActiveX. Use the Variant to Data function to switch between interfaces of an ActiveX object.

If you use the To Variant and Variant to Data functions with LabVIEW classes consider the following caveat.

Variants do not recognize inheritance hierarchies. For example, if you have child data traveling on a parent class wire and you then wire the parent wire to a To Variant function, the variant recognizes only the parent data type. If you wire a child data type to the Variant to Data function to extract the child data, LabVIEW returns an error. You must wire the parent to the Variant to Data function. Then use the To More Specific function to retrieve the child class data.


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