Not Operator

Definition:
Used to perform logical negation on a single expression.

Syntax:
result = Not expr

Details:
The Not operator, also known as the logical negation operator, examines each bit in the supplied expression and sets the corresponding bit in result to its opposite. The following table summarizes the results:

expr bit result bit

0 1

In the case of an integer variable with a value 0, the variable becomes -1. The variable becomes 0, in the case of an integer variable with the value of -1.

That is why True has the value -1, and False has the value 0, because:

Not True = Not -1 = 0 = False

Note: It is important when using Not to always use -1 for True, because only the value -1 when bitwise negated yields 0, any other value such as 1, bitwise negates to something else. In particular “Not 1” yields -2, which is not equal to False.

See Also:
Arithmetic Operators
Comparison Operators
Logical Operators
Operator Precedence

Example:
If Not False Then Print “Must be True.”
If Not True Then Print “Must be False.”