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version 6.0
4D supports two logical operators that work on Boolean expressions: conjunction (AND) and inclusive disjunction (OR). A logical AND returns TRUE if both expressions are TRUE. A logical OR returns TRUE if at least one of the expressions is TRUE.
4D also provides the Boolean functions True, False, and Not. For more information, see the descriptions of these commands.
The following table shows the logical operators:
| Operation | Syntax | Returns | Expression | Value |
| AND | Boolean & Boolean | Boolean | ("A" = "A") & (15 # 3) | True |
| ("A" = "B") & (15 # 3) | False | |||
| ("A" = "B") & (15 = 3) | False | |||
| OR | Boolean | Boolean | Boolean | ("A" = "A") | (15 # 3) | True |
| ("A" = "B") | (15 # 3) | True | |||
| ("A" = "B") | (15 = 3) | False |
The following is the truth table for the AND logical operator:
| Expr1 | Expr2 | Expr1 & Expr2 |
| True | True | True |
| True | False | False |
| False | True | False |
| False | False | False |
The following is the truth table for the OR logical operator:
| Expr1 | Expr2 | Expr1 | Expr2 |
| True | True | True |
| True | False | True |
| False | True | True |
| False | False | False |
Tip
If you need to calculate the exclusive disjunction between Expr1 and Expr2, evaluate:
(Expr1 | Expr2) & Not(Expr1 & Expr2)
See Also
Bitwise Operators, Comparison Operators, Date Operators, Numeric Operators, Operators, Picture Operators, String Operators, Time Operators.
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