Xor Operator (Visual Basic)
Performs a logical exclusion on two Boolean expressions, or a bitwise exclusion on two numeric expressions.
Syntax
result = expression1 Xor expression2
Parts
result
Required. Any Boolean or numeric variable. For Boolean comparison, result is the logical exclusion (exclusive logical disjunction) of two Boolean values. For bitwise operations, result is a numeric value that represents the bitwise exclusion (exclusive bitwise disjunction) of two numeric bit patterns.
expression1
Required. Any Boolean or numeric expression.
expression2
Required. Any Boolean or numeric expression.
Remarks
For Boolean comparison, result is True if and only if exactly one of expression1 and expression2 evaluates to True. That is, if and only if expression1 and expression2 evaluate to opposite Boolean values. The following table illustrates how result is determined.
If expression1 is |
And expression2 is |
The value of result is |
|---|---|---|
True |
True |
False |
True |
False |
True |
False |
True |
True |
False |
False |
False |
Note
In a Boolean comparison, the Xor operator always evaluates both expressions, which could include making procedure calls. There is no short-circuiting counterpart to Xor, because the result always depends on both operands. For short-circuiting logical operators, see AndAlso Operator and OrElse Operator.
For bitwise operations, the Xor operator performs a bitwise comparison of identically positioned bits in two numeric expressions and sets the corresponding bit in result according to the following table.
If bit in expression1 is |
And bit in expression2 is |
The bit in result is |
|---|---|---|
| 1 | 1 | 0 |
| 1 | 0 | 1 |
| 0 | 1 | 1 |
| 0 | 0 | 0 |
Note
Since the logical and bitwise operators have a lower precedence than other arithmetic and relational operators, any bitwise operations should be enclosed in parentheses to ensure accurate execution.
For example, 5 Xor 3 is 6. To see why this is so, convert 5 and 3 to their binary representations, 101 and 011. Then use the previous table to determine that 101 Xor 011 is 110, which is the binary representation of the decimal number 6.
Data Types
If the operands consist of one Boolean expression and one numeric expression, Visual Basic converts the Boolean expression to a numeric value (–1 for True and 0 for False) and performs a bitwise operation.
For a Boolean comparison, the data type of the result is Boolean. For a bitwise comparison, the result data type is a numeric type appropriate for the data types of expression1 and expression2. See the "Relational and Bitwise Comparisons" table in Data Types of Operator Results.
Overloading
The Xor operator can be overloaded, which means that a class or structure can redefine its behavior when an operand has the type of that class or structure. If your code uses this operator on such a class or structure, make sure you understand its redefined behavior. For more information, see Operator Procedures.
Example 1
The following example uses the Xor operator to perform logical exclusion (exclusive logical disjunction) on two expressions. The result is a Boolean value that represents whether exactly one of the expressions is True.
Dim a As Integer = 10
Dim b As Integer = 8
Dim c As Integer = 6
Dim firstCheck, secondCheck, thirdCheck As Boolean
firstCheck = a > b Xor b > c
secondCheck = b > a Xor b > c
thirdCheck = b > a Xor c > b
The previous example produces results of False, True, and False, respectively.
Example 2
The following example uses the Xor operator to perform logical exclusion (exclusive logical disjunction) on the individual bits of two numeric expressions. The bit in the result pattern is set if exactly one of the corresponding bits in the operands is set to 1.
Dim a As Integer = 10 ' 1010 in binary
Dim b As Integer = 8 ' 1000 in binary
Dim c As Integer = 6 ' 0110 in binary
Dim firstPattern, secondPattern, thirdPattern As Integer
firstPattern = (a Xor b) ' 2, 0010 in binary
secondPattern = (a Xor c) ' 12, 1100 in binary
thirdPattern = (b Xor c) ' 14, 1110 in binary
The previous example produces results of 2, 12, and 14, respectively.
