The logical operator NOT behaves differently in
VBScript than it does in the built-in scripting language.
NOT Operator in VBScript
In VBScript, the NOT operator inverts the bits of a
given numeric value, producing its complement number according to
the "two's complement" system of signed numbers that is used by
computers. The table below illustrates the behavior of the NOT
operator in VBScript for the syntax…
result = NOT expression
| If expression is… |
Then result is… |
| −3 |
2 |
| −2 |
1 |
| −1 |
0 |
| 0 |
−1 |
| 1 |
−2 |
| 2 |
−3 |
| 3 |
−4 |
Note: By
default, when you attempt to write any numeric value other than 0
to a
Boolean tag,
the tag automatically assumes a value of 1. Therefore, if
VBScript's NOT operator is applied to a Boolean tag with a value of
1, then the value of the tag does not change; the operator returns
a value of −2, but the tag cannot accept this value so it again
assumes a value of 1.
You can configure IWS to treat Boolean tags like Boolean variables
in VBScript, so that the NOT operator in VBScript will work as
expected. For more information, please see Boolean Tags and Boolean
Variables.
NOT Operator in Built-in
Language
In contrast, the
NOT operator in the Built-in Scripting Language toggles the
given numeric value as if it is a natural boolean. The table below
illustrates the behavior of the NOT operator in the Built-in
Scripting Language for the syntax…
result = NOT expression
| If expression is… |
Then result is… |
| 0 |
1 |
| ≠0 |
0 |