| Keyword |
Description |
| empty |
Used to indicate an uninitialized
variable value. A variable value is uninitialized when
it is first created and no value is assigned to it, or
when a variable value is explicitly set to empty.
Example:
dim x 'the variable x is uninitialized!
x="ff" 'the variable x is NOT uninitialized anymore
x=empty 'the variable x is uninitialized!
Note: This is not the same as Null!! |
| isEmpty |
Used to test if a variable is
uninitialized. Example: If (isEmpty(x)) 'is x
uninitialized? |
| nothing |
Used to indicate an uninitialized
object value, or to disassociate an object variable from
an object to release system resources.
Example: set myObject=nothing |
| is nothing |
Used to test if a value is an
initialized object.
Example: If (myObject Is Nothing) 'is it unset?
Note: If you compare a value to Nothing, you
will not get the right result! Example: If (myObject =
Nothing) 'always false! |
| null |
Used to indicate that a variable
contains no valid data.
One way to think of Null is that someone has
explicitly set the value to "invalid", unlike Empty
where the value is "not set".
Note: This is not the same as Empty or
Nothing!!
Example: x=Null 'x contains no valid data |
| isNull |
Used to test if a value contains
invalid data.
Example: if (isNull(x)) 'is x invalid? |
| true |
Used to indicate a Boolean condition
that is correct (true has a value of -1) |
| false |
Used to indicate a Boolean condition
that is not correct (false has a value of 0) |
