Or Operator (Visual Basic)
Performs a logical disjunction on two Boolean expressions, or a bitwise disjunction on two numeric expressions.
result = expression1 Or expression2
For Boolean comparison, result is False if and only if both expression1 and expression2 evaluate to False. The following table illustrates how result is determined.
If expression1 is |
And expression2 is |
The value of result is |
---|---|---|
True |
True |
True |
True |
False |
True |
False |
True |
True |
False |
False |
False |
Note |
---|
In a Boolean comparison, the Or operator always evaluates both expressions, which could include making procedure calls. The OrElse Operator (Visual Basic) performs short-circuiting, which means that if expression1 is True, then expression2 is not evaluated. |
For bitwise operations, the Or 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 |
1 |
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. |
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 (Visual Basic).
Overloading
The Or 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, be sure you understand its redefined behavior. For more information, see Operator Procedures (Visual Basic).
The following example uses the Or operator to perform an inclusive logical disjunction on two expressions. The result is a Boolean value that represents whether either of the two 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 Or b > c secondCheck = b > a Or b > c thirdCheck = b > a Or c > b
The preceding example produces results of True, True, and False, respectively.
The following example uses the Or operator to perform inclusive logical disjunction on the individual bits of two numeric expressions. The bit in the result pattern is set if either of the corresponding bits in the operands is set to 1.
Dim a As Integer = 10 Dim b As Integer = 8 Dim c As Integer = 6 Dim firstPattern, secondPattern, thirdPattern As Integer firstPattern = (a Or b) secondPattern = (a Or c) thirdPattern = (b Or c)
The preceding example produces results of 10, 14, and 14, respectively.