====== Unassigned function  ======


 
==== Description ====
 
Tests if a variable has been assigned.  Returns True (1) if the variable is unassigned and False (0) if the variable is assigned - the opposite result from the [[assigned|assigned()]] function.
 
==== Syntax ====
 
//truefalse// = Una**ssigned**(//variable//)
 
==== Parameters ====
 
The unassigned() function  is used to determine whether a value has been assigned to a variable. You can avoid "variable not assigned a value" (VNAV) errors, by making sure that any variable you reference in your code has, at minimum, a null value.

Note:  A null value is different from an unassigned value.  A null value is a known, assigned value of %%''%% .  If a variable is unassigned it has an unknown value.

Note:  The unassigned() function requires a function declaration.  The [[assigned|assigned()]] function does not require a function declaration.
 

 
==== Returns ====
 
True (1) if variable is unassigned; false (0) if variable is assigned.
 
==== See Also ====
 
[[assigned|assigned()]]
 
==== Example ====
 
<code>
function RowExists(Table, Key)
declare function unassigned
$insert Logical
Exists = FALSE$
if not(unassigned(Table)) and not(unassigned(Key)) then
  open Table to Handle then
    read Row from Handle, Key then
      Exists = TRUE$
    end
  end
end
return Exists
</code>