arr_count()
Returns the number of rows entered during
an INPUT ARRAY statement.
Syntax
FUNCTION arr_count()
  RETURNS INTEGERUsage
Use arr_count() to determine the number of program records
 that are currently stored in a static program array used by the
 INPUT ARRAY instruction.
This function is typically called inside or after INPUT ARRAY 
 or DISPLAY ARRAY statement.
arr_count() returns
 a positive integer, corresponding to the  index of the furthest record
 within the static program array that the user accessed.  Not all the
 rows counted by arr_count() necessarily contain data
 (for example, if the user presses the Down key more times than there
 are rows of data.
This function is not required when using
 dynamic arrays. In such case, the total  number of rows in defined
 by the  array.getLength() method
 after the dialog, or by the  ui.Dialog.getArrayLength() 
 method during the dialog execution.