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Logical Operators
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Logical Operators
■ Logical (or Boolean) operators perform the following kinds of tasks:
• Bit manipulations • Boolean operations • Tests on multiple relations
■ Visual Basic uses the following six logical operators, listed in order of
precedence:
Operator Description
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NOT Bit-wise complement (logical negative)
AND Conjunction
OR Inclusive OR (disjunction)
XOR Exclusive OR (either OR but not both)
EQV Logical equivalence
IMP Implied (first operand false and second operand true)
■ Logical operators return a True (-1) or False (zero) value to use in
making decisions.
■ The standard syntax for logical operators is:
result = expression-1 operator expression-2
■ Logical (or Boolean) operations in an expression are performed after
arithmetic and relational operations in order of precedence.
See: ◄Arithmetic Operators► ◄Relational Operators►
■ Results of logical operations are returned based on the truth table for
logical operators. See: ◄Truth Table for Logical Operators►
■ Expressions are converted to integers or long integers before a Boolean
operation is performed.
■ Operands of logical operators must be in the range -2,147,483,648 to
2,147,483,647, inclusive; if operands are not in this range, an error
occurs.
■ If the expressions evaluate to 0 or -1, a Boolean operation returns 0 or
-1 as the result. Because Boolean operators do bit-wise calculations,
using values other than 0 for False and -1 for True may produce unexpected
results.
■ Use extra care when bitmasking, since the bit-wise AND and the logical AND
perform the same operation. See: ◄Logical Operators Example►
See: ◄Expressions and Operators Summary►