fieldnames
List of fields in a given object.
(u)=fieldnames(a)
Inputs
a An object that has fields.
Outputs
u The array of names of fields in the given object.


Example
>> //A struct array.
>>a.x=2
>>a.y=10
>>fieldnames(a)
  x
  y
>> // A java object.
>>a=new Vector()
>>fieldnames(a)
  elementData
  elementCount
  capacityIncrement
  serialVersionUID

>>// A Mathnium class 
>>class MClass
 >var  a, b
 >end
>>a=new MClass()
>>fieldnames(a)
  a
  b
>>// An object that does not have any fields
>>fieldnames(2)
null