Re: newbie questions

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  • Posted by ghaberek (admin) Jul 01, 2013
  • 1092 views
DerekParnell said...

There is a difference between an EMPTY sequence and an UNASSIGNED sequence. When a variable is declared, and if there is no initial assignment on the declaration statement, the variable has NO VALUE. It is unassigned. A sequence is not assigned by default to 'empty' when it is declared, but it is in a state called 'unassigned'. 

sequence S_One 
sequence S_Two = {} 
sequence S_Three = {1,2,3} 
 
? S_Three --> {1,2,3} 
? S_Two   --> {} 
? S_One   --> ** CRASH Sequence has not been assigned anything yet.

Also, you can also use object() to determine if a value is assigned or not. 

sequence S_One 
sequence S_Two = {} 
? object( S_One ) -- false 
? object( S_Two ) -- true

-Greg

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