From Clomosy Docs
function Assigned (var P ):Boolean;
The assigned function checks if a reference is null. Returns True if non-zero, False if zero. Using a Nil reference will result in an exception.
Example
var
myValue : Integer;
myValue2 :Integer;
valueStr : String;
{
myValue = 10;
if (Assigned(myValue))
ShowMessage('myValue is not nil')
else ShowMessage('myValue is nil');
myValue2 = Nil;
if (Assigned(myValue2))
ShowMessage('myValue2 is still not nil')
else ShowMessage('myValue2 is nil');
if (Assigned(valueStr))
ShowMessage('valueStr is still not nil')
else ShowMessage('valueStr is nil');
}
Output:
myValue is not nil
myValue2 is nil
valueStr is nil