5.5 Logical Operators
The logical operators take logical operands and produce logical
results, meaning “true or false.” Logical operators are
not true Boolean operators because they may also result in a
system-missing value. See Boolean Values, for more information.
- True if both a and b are true, false otherwise. If one
operand is false, the result is false even if the other is missing. If
both operands are missing, the result is missing.
- True if at least one of a and b is true. If one operand is
true, the result is true even if the other operand is missing. If both
operands are missing, the result is missing.
- True if a is false. If the operand is missing, then the result