Logical Operators
表格 11-6. Logical Operators
Example |
Name |
Result |
$a and $b |
And |
TRUE if both $a and $b are TRUE. |
$a or $b |
Or |
TRUE if either $a or $b is TRUE. |
$a xor $b |
Xor |
TRUE if either $a or $b is TRUE, but not both. |
! $a |
Not |
TRUE if $a is not TRUE. |
$a
$b |
And |
TRUE if both $a and $b are TRUE. |
$a || $b |
Or |
TRUE if either $a or $b is TRUE. |
The reason for the two different variations of "and" and
"or" operators is that they operate at different precedences.
(See
Operator Precedence.)