Logical (Boolean) operators

REXX comparison expressions return a true (1) or false (0) value when processed. Logical operators combine two comparisons and return the true (1) or false (0) value depending on the results of the comparisons.

The logical operators are:

Operator

Meaning

&

AND

Returns 1 if both comparisons are true. For example:

(4 > 2) & (a = a)        /* true, so result is 1  */
(2 > 4) & (a = a)        /* false, so result is 0 */

|

Inclusive OR

Returns 1 if at least one comparison is true. For example: (4 > 2) | (5 = 3) /* at least one is true, so result is 1 */ (2 > 4) | (5 = 3) /* neither one is true, so result is 0 */

&&

Exclusive OR

Returns 1 if only one comparison (but not both) is true. For example:

(4 > 2) && (5 = 3)       /* only one is true, so result is 1 */
(4 > 2) && (5 = 5)       /* both are true, so result is 0 */
(2 > 4) && (5 = 3)       /* neither one is true, so result is 0 */

Prefix ¬ \

Logical NOT

Returns the opposite response. For example:

\ 0:                     /* opposite of 0, so result is 1 */
\ (4 > 2)                /* opposite of true, so result is 0 */

Logical expressions are used in complex comparisons and can be and can act as checkpoints to stop unwanted conditions (such as testing a field for a value of zero before using it as a divisor). When you have a series of logical expressions, for clarification, use one or more sets of parentheses to enclose each expression. For example:

(#46 = 999) | ((#45 > 0) & (#46 / #45) >= .5)