| Logical Operators | ||
|---|---|---|
 | Chapter 3. Operators |  |
Logical Operators
Logical operators are used for doing boolean operations for the purpose of evaluating
multiple conditions that are based on true and false values. They differ from arithmetic
operators in that they typically only return .true or .false
which is then used to make a decision about the flow of the program. They are commonly
used together with comparison operators and arithmetic operators in branching and looping
statements to evaluate whether the loop should continue or decide which branch to take.
and
Operand count
2 or more
Types
.nul, .inf, boolean,
integer, number, string
Description
Gives a boolean result indicating whether or not all the operands are
not .nul, the empty string (""),
zero (0)or .false.
Behavior by type
| Type name | Result for and when applied to this type |
|---|---|
.nul |
If any operand is .nul then the result is
.false
|
.inf |
If all operands are .inf then the result is
.true, otherwise the result depends on the value
of the other operands
|
| boolean |
If any operand is .false then the result is .false
|
| integer |
If any operand is zero (0) then the result is .false
|
| number |
If any operand is zero (0) then the result is .false
|
| string |
If any operand is the empty string then the result is .false
|
or
Operand count
2 or more
Types
.nul, .inf, boolean,
integer, number, string
Description
Gives a boolean result indicating whether or not any operand is
not .nul, the empty string (""),
zero (0)or .false.
Behavior by type
| Type name | Result for or when applied to this type |
|---|---|
.nul |
If all operands are .nul then the result is
.false otherwise the result depends on the value of
the other operands
|
.inf |
If any operand is .inf then the result is
.true
|
| boolean |
If any operand is .true then the result is .true
|
| integer |
If any operand is non-zero then the result is .true
|
| number |
If any operand is non-zero then the result is .true
|
| string |
If any operand is a non-empty string then the result is .true
|
not
Operand count
1
Types
.nul, .inf, boolean,
integer, number, string
Description
Creates a result which is a logical opposite of the input operand
Behavior by type
| Type name | Result when not is applied to this type |
|---|---|
.nul | The result will be .nul |
.inf | The result will be .inf |
| boolean |
.true becomes .false, and
.false becomes .true
|
| integer |
0 becomes 1, and any other
value becomes 0
|
| number |
0 becomes the integer 1,
and any other value becomes the integer 0
|
| string |
The empty string becomes ".", and any other
string becomes the empty string
|