And Operator (Visual Basic)
Performs a logical conjunction on two Boolean expressions, or a bitwise conjunction on two numeric expressions.
result = expression1 And expression2
Parts
result
Required. Any Boolean or numeric expression. For Boolean comparison, result is the logical conjunction of two Boolean values. For bitwise operations, result is a numeric value representing the bitwise conjunction 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 both expression1 and expression2 evaluate to True. The following table illustrates how result is determined.
If expression1 is |
And expression2 is |
The value of result is |
|---|---|---|
True |
True |
True |
True |
False |
False |
False |
True |
False |
False |
False |
False |
Poznámka
In a Boolean comparison, the And operator always evaluates both expressions, which could include making procedure calls. The AndAlso Operator (Visual Basic) performs short-circuiting, which means that if expression1 is False, then expression2 is not evaluated.
When applied to numeric values, the And 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 |
0 |
0 |
1 |
0 |
0 |
0 |
0 |
Poznámka
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 results.
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).
Poznámka
The And 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).
Example
The following example uses the And operator to perform a logical conjunction on two expressions. The result is a Boolean value that represents whether both of the expressions are True.
Dim a As Integer = 10
Dim b As Integer = 8
Dim c As Integer = 6
Dim firstCheck, secondCheck As Boolean
firstCheck = a > b And b > c
secondCheck = b > a And b > c
The preceding example produces results of True and False, respectively.
The following example uses the And operator to perform logical conjunction on the individual bits of two numeric expressions. The bit in the result pattern is set if the corresponding bits in the operands are both 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 And b)
secondPattern = (a And c)
thirdPattern = (b And c)
The preceding example produces results of 8, 2, and 0, respectively.
See Also
Reference
Logical/Bitwise Operators (Visual Basic)
Operator Precedence in Visual Basic
Operators Listed by Functionality (Visual Basic)
AndAlso Operator (Visual Basic)