XOR (Logical Exclusion)
The XOR operator is used to perform a logical exclusion on two numbers.
Syntax
result = Number1 XOR Number2
Example
The example sets the variable Msg based on the value of variables A, B, and C, assuming that no variable is a Null. If A = 10, B = 8, and C = 11, the left expression is True and the right expression is False. Because only one comparison expression is True, the XOR expression evaluates True.
Public A, B, C, Msg As Boolean
'Declare variables.
BeginProg
A = 10: B = 8: C = 11 'Assign values.
If A > B XOR B >
C Then 'Evaluate expressions.
Msg = True
Else
Msg = False
EndIf
Remarks
The XOR operator performs a bit-wise comparison of identically positioned bits in two numeric expressions and sets the corresponding bit in result according to the following table:
| If bit in Number 1 is | And bit in Number2 is | The result is |
|---|---|---|
| 1 | 1 | 0 |
| 1 | 0 | 1 |
| 0 | 1 | 1 |
| 0 | 0 | 0 |
Bit-wise operations are performed on integers; floating point values will first be converted before the bit-wise operation is performed. Although XOR is a bit-wise operator, it is often used to test Boolean (True/False) conditions. Boolean values are implemented as Longs that are restricted to -1 (True) or 0 (False). Any non-zero number >= 1 will evaluate as true (a float value between .999 and 0 when converted to a Long is 0). Because XOR is a bit-wise operation, it is possible to XOR two non-zero numbers (for example, 2 and 4) and get a non-zero number. (XOR will only operate with two non-zero numbers and return 0 if the original numbers are equal.)
| If Number 1 is | And Number2 is | The result is |
|---|---|---|
| -1 | -1 | 0 |
| -1 | NAN Not a number. A data word indicating a measurement or processing error. Voltage overrange, SDI-12 sensor error, and undefined mathematical results can produce NAN.
|
NAN |
| 0 | Any Number | Number2 |
| 0 | NAN | NAN |
Expressions that are evaluated to a number can be used in place of one or both of the numbers.