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  >  Docs Center  >  ENVI API  >  Crop Science  >  ENVIParameterENVIAgCrops::Validate

ENVIParameterENVIAgCrops::Validate

ENVIParameterENVIAgCrops::Validate

This Validate function method returns a Boolean value that indicates whether the VALUE passed to it is valid for the parameter. If the VALUE is invalid, then 0 is returned and the ERROR keyword will be populated with information on why it is invalid. This method allows the user to test the VALUE before setting the parameter’s VALUE and generating an error that must be handled by the user routine.

Syntax


Result = ENVIParameterENVIAgCrops.Validate(Value [, ERROR=variable])

Return Value


The result is a Boolean value indicating if the VALUE is valid for the parameter.

Arguments


Value

The value to test for validity. On successful return, this argument will be typecast to the parameter's TYPE.

Keywords


ERROR (optional)

Set this keyword to a named variable that will contain any error message issued during execution of this routine. If no error occurs, the ERROR variable will be set to a null string (''). If an error occurs and the routine is a function, then the function result will be undefined.

When this keyword is not set and an error occurs, ENVI returns to the caller and execution halts. In this case, the error message is contained within !ERROR_STATE and can be caught using IDL's CATCH routine. See IDL Help for more information on !ERROR_STATE and CATCH.

See the Manage Errors topic in ENVI Help for more information on error handling.

Version History


1.1

Introduced

API Version


3.2

See Also


ENVIParameterENVIAgCrops



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